CHAPTER 12 signals arrive at the output neuron at different times, and the output neuron may go on firing for some time after input has ceased Unlike a reverberating circuit, this type has no feedback loop Once all the neurons in the circuit have fired, the output ceases Continued firing after the stimulus stops is called after-discharge It explains why you can stare at a lamp, then close your eyes and continue to see an image of it for a while Such a circuit is also important in withdrawal reflexes, in which a brief pain produces a longerlasting output to the limb muscles and causes you to draw back your hand or foot from danger Memory and Synaptic Plasticity You may have wondered as you studied this chapter, How am I going to remember all of this? It seems fitting that we end with the subject of how memory works, for you now have the information necessary to understand its cellular and chemical basis The things we learn and remember are not stored in individual “memory cells” in the brain We not have a neuron assigned to remember our phone number and another assigned to remember our grandmother’s face, for example Instead, the physical basis of memory is a pathway through the brain called a memory trace (engram30), in which new synapses have formed or existing synapses have been modified to make transmission easier In other words, synapses are not fixed for life; in response to experience, they can be added, taken away, or modified to make transmission easier or harder Indeed, synapses can be created or deleted in as little as or hours The ability of synapses to change is called synaptic plasticity Think about when you learned as a child to tie your shoes The procedure was very slow, confusing, and laborious at first, but eventually it became so easy you could it with little thought—like a motor program playing out in your brain without requiring your conscious attention It became easier to because the synapses in a certain pathway were modified to allow signals to travel more easily across them than across “untrained” synapses The process of making transmission easier is called synaptic potentiation (one form of synaptic plasticity) Neuroscientists still argue about how to classify the various forms of memory, but three kinds often recognized are immediate memory, short-term memory, and long-term memory We also know of different modes of synaptic potentiation that last from just a few seconds to a lifetime, and we can correlate these at least tentatively with different forms of memory Immediate Memory Immediate memory is the ability to hold something in mind for just a few seconds By remembering what just 30 en = inner; gram = mark, trace, record sal78259_ch12_439-477.indd 471 Nervous Tissue 471 happened, we get a feeling for the flow of events and a sense of the present Immediate memory is indispensable to the ability to read; you must remember the earliest words of a sentence until you get to its end in order to extract any meaning from the sentence You could not make any sense of what you read if you forgot each word as soon as you moved on to the next one Immediate memory might be based on reverberating circuits Our impression of what just happened can thus reecho in our minds for a few seconds as we experience the present moment and anticipate the next one Short-Term Memory Short-term memory (STM) lasts from a few seconds to a few hours Information stored in STM may be quickly forgotten if we stop mentally reciting it, we are distracted, or we have to remember something new Working memory is a form of STM that allows us to hold an idea in mind long enough to carry out an action such as calling a telephone number we just looked up, working out the steps of a mathematics problem, or searching for a lost set of keys while remembering where we have already looked It is limited to a few bits of information such as the digits of a telephone number It has long been thought that working memory is based on persistent activity in a reverberating circuit of neurons, but recent evidence leans toward the storage of working memory in a circuit of facilitated synapses that can remain quiescent (consuming no energy) most of the time, but be reactivated by a new sensory input Such synaptic facilitation, as it is called (different from the facilitation of one neuron by another that we studied earlier in the chapter), can be induced by tetanic stimulation, the rapid arrival of repetitive signals at a synapse Each signal causes a certain amount of Ca2+ to enter the synaptic knob If signals arrive very rapidly, the neuron cannot pump out all the Ca2+ admitted by one action potential before the next action potential occurs More and more Ca2+ accumulates in the knob Since Ca2+ is what triggers the release of neurotransmitter, each new signal releases more neurotransmitter than the one before With more neurotransmitter, the EPSPs in the postsynaptic cell become stronger and stronger, and that cell is more likely to fire Memories lasting for a few hours, such as remembering what someone said to you earlier in the day or remembering an upcoming appointment, may involve posttetanic potentiation In this process, the Ca2+ level in the synaptic knob stays elevated for so long that another signal, coming well after the tetanic stimulation has ceased, releases an exceptionally large burst of neurotransmitter That is, if a synapse has been heavily used in the recent past, a new stimulus can excite the postsynaptic cell more easily Thus, your memory may need only a slight jog to recall something from several hours earlier 11/15/10 8:59 AM 472 PART THREE Integration and Control Long-Term Memory Long-term memory (LTM) lasts up to a lifetime and is less limited than STM in the amount of information it can store LTM allows you to memorize the lines of a play, the words of a favorite song, or (one hopes!) textbook information for an exam On a still longer timescale, it enables you to remember your name, the route to your home, and your childhood experiences There are two forms of long-term memory: declarative and procedural Declarative memory is the retention of events and facts that you can put into words—numbers, names, dates, and so forth Procedural memory is the retention of motor skills—how to tie your shoes, play a musical instrument, or type on a keyboard These forms of memory involve different regions of the brain but are probably similar at the cellular level Some LTM involves the physical remodeling of synapses or the formation of new ones through the growth and branching of axon terminals and dendrites In the pyramidal cells of the brain, the dendrites are studded with knoblike dendritic spines that increase the area of synaptic contact Studies on fish and other experimental animals have shown that social and sensory deprivation causes these spines to decline in number, while a richly stimulatory environment causes them to proliferate—an intriguing clue to the importance of a stimulating environment to infant and child development In some cases of LTM, a new synapse grows beside the original one, giving the presynaptic cell twice as much input into the postsynaptic cell LTM can also be grounded in molecular changes called long-term potentiation This involves NMDA31 receptors, which are glutamate-binding receptors found on the synaptic knobs of pyramidal cells NMDA receptors are usually blocked by magnesium ions (Mg2+), but when they bind glutamate and are simultaneously subjected to tetanic stimulation, they expel the Mg2+ and open to DEEPER INSIGHT 12.4 Clinical Application Alzheimer and Parkinson Diseases Alzheimer and Parkinson diseases are the two most common degenerative disorders of the brain Both are associated with neurotransmitter deficiencies Alzheimer32 disease (AD) may begin before the age of 50 with signs so slight and ambiguous that early diagnosis is difficult One of its first signs is memory loss, especially for recent events A person with AD may ask the same questions repeatedly, show a reduced attention span, and become disoriented and lost in previously familiar places 31 32 admit Ca2+ into the dendrite When Ca2+ enters, it acts as a second messenger that leads to a variety of effects: • • • The neuron produces even more NMDA receptors, which makes it more sensitive to glutamate in the future It synthesizes proteins concerned with physically remodeling a synapse It releases nitric oxide, which diffuses back to the presynaptic neuron and triggers still more glutamate release You can see that in all of these ways, long-term potentiation can increase transmission across “experienced” synapses Remodeling a synapse or installing more neurotransmitter receptors has longer-lasting effects than facilitation or posttetanic potentiation The anatomical sites of memory are discussed in chapter 14 in connection with brain anatomy Regardless of the sites, however, the cellular mechanisms are as described here Before You Go On Answer the following questions to test your understanding of the preceding section: 22 Contrast the two types of summation at a synapse 23 Describe how the nervous system communicates quantitative and qualitative information about stimuli 24 List the four types of neural circuits and describe their similarities and differences Discuss the unity of form and function in these four types—that is, explain why each type would not perform as it does if its neurons were connected differently 25 How does long-term potentiation enhance the transmission of nerve signals along certain pathways? Family members often feel helpless and confused as they watch their loved one’s personality gradually deteriorate beyond recognition The AD patient may become moody, confused, paranoid, combative, or hallucinatory—he or she may ask irrational questions such as, Why is the room full of snakes? The patient may eventually lose even the ability to read, write, talk, walk, and eat Death ensues from pneumonia or other complications of confinement and immobility AD affects about 11% of the U.S population over the age of 65; the incidence rises to 47% by age 85 It accounts for nearly half of all nursing home admissions and is a leading cause of death among the elderly AD claims about 100,000 lives per year in the United States Diagnosis of AD can be confirmed by autopsy There is atrophy of some of the gyri (folds) of the cerebral cortex and the hippocampus, N-methyl-D-aspartate, a chemical similar to glutamate Alois Alzheimer (1864–1915), German neurologist sal78259_ch12_439-477.indd 472 11/15/10 8:59 AM CHAPTER 12 an important center of memory Nerve cells exhibit neurofibrillary tangles—dense masses of broken and twisted cytoskeleton (fig. 12.31) Alois Alzheimer first observed these in 1907 in the brain of a patient who had died of senile dementia The more severe the signs of disease, the more neurofibrillary tangles are seen at autopsy In the intercellular spaces, there are senile plaques consisting of aggregations of cells, altered nerve fibers, and a core of β-amyloid protein—the breakdown product of a glycoprotein of plasma membranes Amyloid protein is rarely seen in elderly people without AD It is now widely believed to be the crucial factor that triggers all the other aspects of AD pathology Intense biomedical research efforts are currently geared toward identifying the causes of AD and developing treatment strategies Three genes on chromosomes 1, 14, and 21 have been implicated in various forms of early- and late-onset AD Interestingly, persons with Down syndrome (trisomy-21), who have three copies of chromosome 21 instead of the usual two, tend to show early-onset Alzheimer disease Nongenetic (environmental) factors also seem to be involved As for treatment, considerable attention now focuses on trying to halt β-amyloid formation or stimulate the immune system to clear β-amyloid from the brain tissue, but clinical trials in both of these approaches have been suspended until certain serious side effects can be resolved AD patients show deficiencies of acetylcholine (ACh) and nerve growth factor (NGF) Some patients show improvement when treated with NGF or cholinesterase inhibitors, but results so far have been modest Parkinson33 disease (PD), also called paralysis agitans or parkinsonism, is a progressive loss of motor function beginning in a person’s 50s or 60s It is due to degeneration of dopamine-releasing neurons in a portion of the brain called the substantia nigra A gene has recently been identified for a hereditary form of PD, but most cases are nonhereditary and of little-known cause; some authorities suspect environmental neurotoxins Dopamine (DA) is an inhibitory neurotransmitter that normally prevents excessive activity in motor centers of the brain called the basal nuclei Degeneration of dopamine-releasing neurons leads to an excessive ratio of ACh to DA, causing hyperactivity of the basal nuclei As a result, a person with PD suffers involuntary muscle contractions These take such forms as shaking of the hands (tremor) and compulsive “pill-rolling” motions of the thumb and fingers In addition, the facial muscles may become rigid and produce a staring, expressionless face with a slightly open mouth The patient’s range of motion diminishes He or she takes smaller steps and develops a slow, shuffling gait with a forward-bent posture and a tendency to fall forward Speech becomes slurred and handwriting becomes cramped and eventually illegible Tasks such as buttoning clothes and preparing food become increasingly laborious Patients cannot be expected to recover from PD, but its effects can be alleviated with drugs and physical therapy Treatment with dopamine is ineffective because it cannot cross the blood–brain barrier, but its precursor, levodopa (L-dopa), does cross the barrier and has been used to treat PD since the 1960s L-dopa affords some relief, but it does not slow progression of the disease and it has undesirable side effects on the liver and heart It is effective for only to 10 years of treatment A newer drug, deprenyl, is a monoamine oxidase (MAO) 33 Nervous Tissue 473 inhibitor that retards neural degeneration and slows the development of PD A surgical technique called pallidotomy has been used since the 1940s to quell severe tremors It involves the destruction of a small portion of cerebral tissue in an area called the globus pallidus Pallidotomy fell out of favor in the late 1960s when L- dopa came into common use By the early 1990s, however, the limitations of L-dopa had become apparent, while MRI- and CT-guided methods had improved surgical precision and reduced the risks of brain surgery Pallidotomy has thus made a comeback Other surgical treatments for parkinsonism target brain areas called the subthalamic nucleus and the ventral intermediate nucleus of the thalamus, and involve either the destruction of tiny areas of tissue or the implantation of a stimulating electrode Such procedures are generally used only in severe cases that are unresponsive to medication Shrunken gyri Wide sulci (a) Neurons with neurofibrillary tangles Senile plaque (b) FIGURE 12.31 Alzheimer Disease (a) Brain of a person who died of AD Note the shrunken folds of cerebral tissue (gyri) and wide gaps (sulci) between them (b) Cerebral tissue from a person with AD Neurofibrillary tangles are present within the neurons, and a senile plaque is evident in the extracellular matrix James Parkinson (1755–1824), British physician sal78259_ch12_439-477.indd 473 11/15/10 8:59 AM CONNECTIVE ISSUES Effects of the NERVOUS SYSTEM on Other Organ Systems INTEGUMENTARY SYSTEM Cutaneous nerves regulate piloerection, sweating, cutaneous vasoconstriction and vasodilation, and heat loss through the body surface, and provide for cutaneous sensations such as touch, itch, tickle, pressure, heat, and cold LYMPHATIC/IMMUNE SYSTEM Nerves to lymphatic organs influence the development and activity of immune cells; emotional states influence susceptibility to infection and other failures of immunity RESPIRATORY SYSTEM SKELETAL SYSTEM Nervous stimulation maintains the muscle tension that stimulates bone growth and remodeling; nerves in the bones respond to strains and fractures MUSCULAR SYSTEM Skeletal muscles cannot contract without nervous stimulation; the nervous system controls all body movements and muscle tone The brainstem regulates the rhythm of breathing, monitors blood pH and blood gases, and adjusts the respiratory rate and depth to control these within normal ranges URINARY SYSTEM Sympathetic nerves modify the rate of urine production by the kidneys; nervous stimulation of urinary sphincters aids in urine retention in the bladder, and nervous reflexes control its emptying ENDOCRINE SYSTEM The hypothalamus controls the pituitary gland; the sympathetic nervous system controls the adrenal medulla; neuroendocrine cells are neurons that secrete hormones such as oxytocin; sensory and other nervous input influences the secretion of numerous other hormones CIRCULATORY SYSTEM The nervous system regulates the rate and force of the heartbeat, regulates blood vessel diameters, monitors and controls blood pressure and blood gas concentrations, routes blood to organs where needed, and influences blood clotting DIGESTIVE SYSTEM The nervous system regulates appetite, feeding behavior, digestive secretion and motility, and defecation REPRODUCTIVE SYSTEM The nervous system regulates sex drive, arousal, and orgasm; the brain regulates the secretion of pituitary hormones that control spermatogenesis in males and the ovarian cycle in females; the nervous system controls various aspects of pregnancy and childbirth; the brain produces oxytocin, which is involved in labor contractions and lactation 474 sal78259_ch12_439-477.indd 474 11/15/10 8:59 AM CHAPTER 12 Nervous Tissue 475 STUDY GUIDE Assess Your Learning Outcomes To test your knowledge, discuss the following topics with a study partner or in writing, ideally from memory 12.1 Overview of the Nervous System (p 440) What the nervous and endocrine systems have in common Three fundamental functions of the nervous system; the roles of receptors and effectors in carrying out these functions Difference between the central nervous system (CNS) and peripheral nervous system (PNS); between the sensory and motor divisions of the PNS; and between the somatic and visceral subdivisions of both the sensory and motor divisions The autonomic nervous system and its two divisions 12.2 Properties of Neurons (p 441) Three fundamental physiological properties of neurons Differences between sensory (afferent) neurons, interneurons (association neurons), and motor (efferent) neurons The parts of a generalized multipolar neuron, and their functions Differences between multipolar, bipolar, unipolar, and anaxonic neurons; an example of each Ways in which neurons transport substances between the neurosoma and the distal ends of the axon 12.3 Supportive Cells (Neuroglia) (p 446) Six kinds of neuroglia; the structure and functions of each; and which kinds are found in the CNS and which ones in the PNS Structure of the myelin sheath, and how CNS and PNS glial cells produce it How fiber diameter and the presence or absence of myelin affect the conduction speed of a nerve fiber The regeneration of a damaged nerve fiber; the role of Schwann cells, the basal lamina, and neurilemma in regeneration; and why CNS neurons cannot regenerate sal78259_ch12_439-477.indd 475 12.4 Electrophysiology of Neurons (p 451) The meanings of electrical potential and resting membrane potential (RMP); the typical voltage of an RMP What an electrical current is, and how sodium ions and gated membrane channels generate a current How stimulation of a neuron generates a local potential; the physiological properties of a local potential Special properties of the trigger zone and unmyelinated regions of a nerve fiber that enable these regions to generate action potentials The mechanism of an action potential; how it relates to ion flows and the action of membrane channels; and what is meant by depolarization and repolarization of the plasma membrane during local and action potentials The all-or-none law and how it applies to an action potential; other properties of action potentials in contrast to local potentials The basis and significance of the refractory period that follows an action potential How one action potential triggers another; how a chain reaction of action potentials constitutes a nerve signal in an unmyelinated nerve fiber; and what normally prevents the signal from traveling backward to the neurosoma Saltatory conduction in a myelinated nerve fiber; differences in conduction mechanisms of the nodes of Ranvier and the internodes; and why signals travel faster in myelinated fibers than in unmyelinated fibers of comparable size 12.5 Synapses (p 460) The structure and locations of synapses The role of neurotransmitters in synaptic transmission Categories of neurotransmitters and common examples of each Why the same neurotransmitter can have different effects on different cells Excitatory synapses; how acetylcholine and norepinephrine excite a postsynaptic neuron Inhibitory synapses; how γ-aminobutyric acid (GABA) inhibits a postsynaptic neuron How second-messenger systems function at synapses Three ways in which synaptic transmission is ended Neuromodulators, their chemical nature, and how they affect synaptic transmission 12.6 Neural Integration (p 466) Why synapses slow down nervous communication; the overriding benefit of synapses The meaning of excitatory and inhibitory postsynaptic potentials (EPSPs and IPSPs) Why the production of an EPSP or IPSP may depend on both the neurotransmitter released by the presynaptic neuron and the type of receptor on the postsynaptic neuron How a postsynaptic neuron’s decision to fire depends on the ratio of EPSPs to IPSPs Temporal and spatial summation, where they occur, and how they determine whether a neuron fires Mechanisms of facilitation and presynaptic inhibition, and how communication between two neurons can be influenced by a third neuron employing one of these mechanisms Mechanisms of neural coding; how a neuron communicates qualitative and quantitative information Why the refractory period sets a limit to how frequently a neuron can fire The meanings of neural pool and neural circuit 10 The difference between a neuron’s discharge zone and facilitated zone, and how this relates to neurons working in groups 11 Diverging, converging, reverberating, and parallel after-discharge circuits of neurons; examples of their relevance to familiar body functions 11/15/10 8:59 AM 476 PART THREE Integration and Control 12 The cellular basis of memory; what memory consists of in terms of neural pathways, and how it relates to synaptic plasticity and potentiation 13 Types of things remembered in immediate memory, short-term memory (STM), and long-term memory (LTM), and in the declarative and procedural forms of LTM 14 Neural mechanisms thought to be involved in these different forms of memory Testing Your Recall The integrative functions of the nervous system are performed mainly by a afferent neurons b efferent neurons c neuroglia d sensory neurons e interneurons An IPSP is of the postsynaptic neuron a a refractory period b an action potential c a depolarization d a repolarization e a hyperpolarization The highest density of voltage-gated ion channels is found on the of a neuron a dendrites b soma c nodes of Ranvier d internodes e synaptic knobs Saltatory conduction occurs only a at chemical synapses b in the initial segment of an axon c in both the initial segment and axon hillock d in myelinated nerve fibers e in unmyelinated nerve fibers The soma of a mature neuron lacks a a nucleus b endoplasmic reticulum c lipofuscin d centrioles e ribosomes The glial cells that fight infections in the CNS are a microglia b satellite cells c ependymal cells d oligodendrocytes e astrocytes Posttetanic potentiation of a synapse increases the amount of in the synaptic knob a neurotransmitter b neurotransmitter receptors c calcium d sodium e NMDA c facilitated circuits d diverging circuits e converging circuits 11 Neurons that convey information to the CNS are called sensory, or , neurons 12 To perform their role, neurons must have the properties of excitability, secretion, and is a period of time in 13 The which a neuron is producing an action potential and cannot respond to another stimulus of any strength Some neurotransmitters can have either excitatory or inhibitory effects depending on the type of a receptors on the postsynaptic cell b synaptic vesicles in the axon c synaptic potentiation that occurs d postsynaptic potentials on the synaptic knob e neuromodulator involved 14 Neurons receive incoming signals by way of specialized extensions of the cell called Differences in the volume of a sound are likely to be encoded by differences in in nerve fibers from the inner ear a neurotransmitters b signal conduction velocity c types of postsynaptic potentials d firing frequency e voltage of the action potentials 17 The trigger zone of a neuron consists of its and 10 Motor effects that depend on repetitive output from a neural pool are most likely to use a parallel after-discharge circuits b reverberating circuits 15 In the CNS, myelin is produced by glial cells called 16 A myelinated nerve fiber can produce action potentials only in specialized regions called 18 The neurotransmitter secreted at an adrenergic synapse is 19 A presynaptic nerve fiber cannot cause other neurons in its to fire, but it can make them more sensitive to stimulation from other presynaptic fibers 20 are substances released along with a neurotransmitter that modify the neurotransmitter’s effect Answers in appendix B Building Your Medical Vocabulary State a medical meaning of each word element below, and give a term in which it or a slight variation of it is used antero2 -aps astro- -grad dendro- neuro- -fer sclero- gangli- 10 somatoAnswers in appendix B sal78259_ch12_439-477.indd 476 11/15/10 8:59 AM CHAPTER 12 Nervous Tissue 477 True or False Determine which five of the following statements are false, and briefly explain why During an action potential, most of the Na+ and K+ exchange places across the plasma membrane A neuron never has more than one axon Excitatory postsynaptic potentials lower the threshold of a neuron and thus make it easier to stimulate Oligodendrocytes perform the same function in the brain as Schwann cells in the peripheral nerves A resting neuron has a higher concentration of K+ in its cytoplasm than in the extracellular fluid surrounding it The absolute refractory period sets an upper limit on how often a neuron can fire A given neurotransmitter has the same effect no matter where in the body it is secreted Myelinated nerve fibers conduct signals more rapidly than unmyelinated ones because they have nodes of Ranvier Learning occurs by increasing the number of neurons in the brain tissue 10 Mature neurons are incapable of mitosis Answers in appendix B Testing Your Comprehension Schizophrenia is sometimes treated with drugs such as chlorpromazine that inhibit dopamine receptors A side effect is that patients begin to develop muscle tremors, speech impairment, and other disorders similar to Parkinson disease Explain Suppose a poison were to slow down the Na+–K+ pumps of nerve cells How would this affect the resting membrane potentials of neurons? Would it make neurons more excitable than normal, or make them more difficult to stimulate? Explain Hyperkalemia is an excess of potassium in the extracellular fluid What effect would this have on the resting membrane potentials of the nervous system and on neural excitability? The unity of form and function is an important concept in understanding synapses Give two structural reasons why nerve signals cannot travel backward across a chemical synapse What might be the consequences if signals did travel freely in both directions? The local anesthetics lidocaine (Xylocaine) and procaine (Novocaine) prevent voltage-gated Na+ channels from opening Explain why this would block the conduction of pain signals in a sensory nerve Answers at www.mhhe.com/saladin6 Improve Your Grade at www.mhhe.com/saladin6 Download mp3 audio summaries and movies to study when it fits your schedule Practice quizzes, labeling activities, games, and flashcards offer fun ways to master the chapter concepts Or, download image PowerPoint files for each chapter to create a study guide or for taking notes during lecture sal78259_ch12_439-477.indd 477 11/15/10 8:59 AM CHAPTER 13 THE SPINAL CORD, SPINAL NERVES, AND SOMATIC REFLEXES Cross section through two fascicles (bundles) of nerve fibers in a nerve CHAPTER OUTLINE 13.1 The Spinal Cord 479 • Functions 479 • Surface Anatomy 479 • Meninges of the Spinal Cord 480 • Cross-Sectional Anatomy 482 • Spinal Tracts 483 13.2 The Spinal Nerves 487 • General Anatomy of Nerves and Ganglia 488 • Spinal Nerves 490 • Nerve Plexuses 493 • Cutaneous Innervation and Dermatomes 500 13.3 Somatic Reflexes 500 • The Nature of Reflexes 500 • The Muscle Spindle 501 • The Stretch Reflex 503 • The Flexor (Withdrawal) Reflex 504 • The Crossed Extension Reflex 505 • The Tendon Reflex 505 Study Guide 508 DEEPER INSIGHTS 13.1 Clinical Application: Spina Bifida 482 13.2 Clinical Application: Poliomyelitis and Amyotrophic Lateral Sclerosis 488 13.3 Clinical Application: Shingles 494 13.4 Clinical Application: Nerve Injuries 497 13.5 Clinical Application: Spinal Cord Trauma 507 Module 7: Nervous System 478 sal78259_ch13_478-510.indd 478 11/15/10 9:00 AM CHAPTER 13 Brushing Up… • A knowledge of basic neuron structure (p 442) is indispensable for understanding this chapter • In this chapter’s discussion of spinal reflexes, it is necessary to be familiar with the ways muscles work in groups at a joint, especially antagonistic muscles You can review that at page 318 • An understanding of excitatory and inhibitory postsynaptic potentials (EPSPs and IPSPs) (p 466) and the parallel after-discharge type of neural circuit (p 470) are also important for understanding spinal reflexes E very year in the United States, thousands of people become paralyzed by spinal cord injuries, with devastating effects on their quality of life The treatment of such injuries is one of the most lively areas of medical research today Therapists in this specialty must know spinal cord anatomy and function to understand their patients’ functional deficits and prospects for improvement and to plan an appropriate regimen of treatment Such knowledge is necessary, as well, for understanding paralysis resulting from strokes and other brain injuries The spinal cord is the “information highway” that connects the brain with the lower body; it contains the neural routes that explain why a lesion to a specific part of the brain results in a functional loss in a specific locality in the lower body In this chapter, we will study not only the spinal cord but also the spinal nerves that arise from it with ladderlike regularity at intervals along its length Thus, we will examine components of both the central and peripheral nervous systems, but these components are so closely related, structurally and functionally, that it is appropriate to consider them together Similarly, the brain and cranial nerves will be considered together in the following chapter Chapters 13 and 14 therefore elevate our study of the nervous system from the cellular level (chapter 12) to the organ and system levels 13.1 The Spinal Cord Expected Learning Outcomes When you have completed this section, you should be able to a state the three principal functions of the spinal cord; b describe its gross and microscopic structure; and c trace the pathways followed by nerve signals traveling up and down the spinal cord Functions The spinal cord serves four principal functions: Conduction It contains bundles of nerve fibers that conduct information up and down the cord, sal78259_ch13_478-510.indd 479 The Spinal Cord, Spinal Nerves, and Somatic Reflexes 479 connecting different levels of the trunk with each other and with the brain This enables sensory information to reach the brain, motor commands to reach the effectors, and input received at one level of the cord to affect output from another level Neural integration Pools of spinal neurons receive input from multiple sources, integrate the information, and execute an appropriate output For example, the spinal cord can integrate the stretch sensation from a full bladder with cerebral input concerning the appropriate time and place to urinate and execute control of the bladder accordingly Locomotion Walking involves repetitive, coordinated contractions of several muscle groups in the limbs Motor neurons in the brain initiate walking and determine its speed, distance, and direction, but the simple repetitive muscle contractions that put one foot in front of another, over and over, are coordinated by groups of neurons called central pattern generators in the cord These neural circuits produce the sequence of outputs to the extensor and flexor muscles that cause alternating movements of the lower limbs Reflexes Reflexes are involuntary stereotyped responses to stimuli, such as the withdrawal of a hand from pain They involve the brain, spinal cord, and peripheral nerves Surface Anatomy The spinal cord (fig 13.1) is a cylinder of nervous tissue that arises from the brainstem at the foramen magnum of the skull It passes through the vertebral canal as far as the inferior margin of the first lumbar vertebra (L1) or slightly beyond In adults, it averages about 45 cm long and 1.8 cm thick (about as thick as one’s little finger) Early in fetal development, the cord extends for the full length of the vertebral column However, the vertebral column grows faster than the spinal cord, so the cord extends only to L3 by the time of birth and to L1 in an adult Thus, it occupies only the upper two-thirds of the vertebral canal; the lower one-third is described shortly The cord gives rise to 31 pairs of spinal nerves The first pair passes between the skull and vertebra C1, and the rest pass through the intervertebral foramina Although the spinal cord is not visibly segmented, the part supplied by each pair of nerves is called a segment The cord exhibits longitudinal grooves on its anterior and posterior sides— the anterior median fissure and posterior median sulcus, respectively (fig 13.2b) The spinal cord is divided into cervical, thoracic, lumbar, and sacral regions It may seem odd that it has a sacral region when the cord itself ends well above the sacrum These regions, however, are named for the level of the vertebral column from which the spinal nerves emerge, not for the vertebrae that contain the cord itself 11/15/10 9:00 AM 480 PART THREE Integration and Control FIGURE 13.1 The Spinal Cord, Posterior Aspect (a) Overview of spinal cord structure (b) Detail of the spinal cord and associated structures C1 Cervical enlargement Cervical spinal nerves C7 Dural sheath Subarachnoid space Thoracic spinal nerves Spinal cord Vertebra (cut) Lumbar enlargement Spinal nerve T12 Spinal nerve rootlets Medullary cone Posterior median sulcus Lumbar spinal nerves Cauda equina Subarachnoid space Epidural space Posterior root ganglion L5 Rib Arachnoid mater Terminal filum Sacral spinal nerves Dura mater S5 Col (b) (a) In two areas, the cord is a little thicker than elsewhere In the inferior cervical region, a cervical enlargement gives rise to nerves of the upper limbs In the lumbosacral region, there is a similar lumbar enlargement that issues nerves to the pelvic region and lower limbs Inferior to the lumbar enlargement, the cord tapers to a point called the medullary cone (conus medullaris) Arising from the lumbar enlargement and medullary cone is a bundle of nerve roots that occupy the vertebral canal from L2 to S5 This bundle, named the cauda equina1 (CAW-duh ee-KWY-nah) for its resemblance to a horse’s tail, innervates the pelvic organs and lower limbs cauda = tail; equin = horse sal78259_ch13_478-510.indd 480 Apply What You Know Spinal cord injuries commonly result from fractures of vertebrae C5 to C6, but never from fractures of L3 to L5 Explain both observations Meninges of the Spinal Cord The spinal cord and brain are enclosed in three fibrous connective tissue membranes called meninges2 (meh-NINjeez)—singular, meninx (MEN-inks) (fig 13.2) These membranes separate the soft tissue of the central nervous system menin = membrane 11/15/10 9:00 AM of stomach, 967 of urine, 918, 919t Phagocytes, 823 Phagocytosis, 98, 98–99, 101t liver functions in, 1022, 1022t of pathogens, 824, 825, 829, 829, 834 Phagolysosome, 98, 98–99 Phagosome, 98, 98 Phallus, 1037 Pharyngeal tonsils, 820, 820, 858 Pharyngotympanic tube, 597, 598 Pharynx, 382, 962–963 anatomy of, 856, 857, 858 muscles of, 327, 329t Phasic receptors, 585 Phasic response, 502 Phenotype, 135 Phenylketonuria, 918, 1119 Pheochromocytoma, 668, 672t Pheomelanin, 187 Pheromones, 595 Philtrum, 381 Phlebotomy, 710 Phonation, 857 Phophodiesterase inhibitors, 1057, 1057 Phophodiesterase type 5, 1057 Phosphagen system, 423–424, 424, 425 Phosphatases, 987 acid phosphatase, 220, 1047 ATPases, 71–72 glucose 6-phosphatase, 1018–1019, 1019 Phosphate(s) electrolyte balance, 941 homeostasis, 224 tubular reabsorption of, 911, 911, 914 Phosphate buffer system, 943 Phosphate groups, 59, 59 Phosphodiesterase, 661 Phosphoglyceraldehyde, 1014 Phosphokinases, 72 Phospholipase, 661, 662, 663 Phospholipids, 62t, 64, 65, 84, 84, 1006 Phosphorus, 1010, 1010t Phosphorylation, 72, 1013, 1013 Photoaging, 1125, 1126 Photons, 56 Photopic vision, 620, 620, 623, 624 Photopsin, 620 Photopupillary reflex, 616 Photoreceptor cells, 619, 619–620, 620 Photoreceptors, 585 Phototherapy, 646, 694 pH partitioning, 55 Phylloquinone See Vitamin K Physical activity See Exercise Physical half-life, 45–46 Physical protection of brain, role of CSF in, 521 role of blood in, 679 role of skeleton in, 207 Physiological buffers, 942 Physiological dead space, 874 Physiological variation, 16 Physiology, 2, Pia mater, 481, 482, 516, 517, 518 Pigment epithelium, 613, 619, 619, 620 Pilus (pili) See Hair Pineal gland, 515, 530, 635, 639, 645, 653t Pinna, 381, 597, 598 Pinocytosis, 99, 101t, 659, 659, 766 Pinocytotic vesicles, 99, 100 Pitcher’s arm, 374 Pitch of sound, 596, 596 Pituitary dwarfism, 219, 668, 672t Pituitary gland, 515, 640 anatomy of, 638, 639, 640 control of secretion, 643–644, 644 disorders of, 668, 668, 672t embryonic development of, 638, 638 hormones produced in, 641–643, 641t, 642, 1080, 1080 male climacteric and, 1049 oxytocin secretion, 1091 in pregnancy, 1088 Pituitary thyrotropin, 1088, 1088t Placebo, Placenta, 1087, 1112, 1113, 1113 development of, 1111 endocrine functions of, 653, 654t functions of, 1114t Placental barrier, 1114 Placental blood, 695 Placental conductivity, 1114 Placental nutrition, 1113, 1113 Placental stage of labor, 1092, 1093 Placenta previa, 1095t Placentation, 1112, 1113 Planes of section, 146, 146 Planetary model of atoms, 44, 44, 45 Plantar flexion, 297, 297 Plant protein, 1009 Plaque complicated, 745, 745 dental, 961 senile plaques, 473, 473, 1127 Plasma, 680, 681–682, 682t, 931 as ground substance in blood, 161 plasma protein deficiency, 683, 683 Plasma cells, 813 in fibrous connective tissue, 154 humoral immunity, 837, 838, 839 specific immunity, 842t Plasma membrane, 13, 81, 83, 83–87, 84, 109t glycolysis and, 1013 lipids, 84, 84–85 of muscle fiber, 403, 404 polarization of, 410–411 proteins, 85, 85–86, 86, 91 of red blood cells, 684 replaced by exocytosis, 100 second messengers, 86–87, 87 Plasmapheresis, 434 Plasma proteins, 681, 682t, 1022, 1022t Plasma volume expanders, 949 Plasmin, 707, 708 Plasminogen, 707, 708 Plasticity of smooth muscle, 433 Plateau phase female, 1085, 1086 male, 1055, 1056, 1057 Platelet(s), 162, 162, 678, 680, 680, 828t form and function, 703, 703 production of, 703, 703, 709t Platelet count, 681t Platelet-derived growth factor, 830 Platelet factors, 705, 706, 707t Platelet plugs, 703, 704, 704 Platelet repulsion, 708 Pleiotropy, 136–137, 137, 690 Pleurae, 384, 856 parietal, 35, 35, 36, 864, 866 visceral, 35, 35–36, 864, 866 Pleural cavity, 35, 35, 35t, 37, 386, 390, 856 Pleural effusion, 936 Pleural fluid, 35, 866 Plexuses nerve (See Nerve plexuses) vascular (See Vascular plexuses) Plicae circulares, 977, 981 Pluripotent stem cells, 172, 176, 684 Pneumocystis infection, 845 Pneumonia, 881, 886, 888t, 1128 Pneumotaxic center, 869, 870 Pneumothorax, 866, 872 Podocytes, 901, 902, 906, 907 Poisoning, 701, 925 Poisons, 182 Polar covalent bonds, 48t, 49, 49 Polarization, 410–411, 453 Poliomyelitis, 488, 870 Poliovirus, 100 Pollex See Thumb Pollution, 1054 Polycythemia, 688, 689 Polydactyly, 137, 139 Polydipsia, 670 Polygenic inheritance, 136, 136 Polygonal cells, 80, 80 Polymerization, 59–60, 60 Polymers, 59–60, 60 Polymorphonuclear leukocytes (PMNs), 697 Polypeptides, 67, 655, 655t, 986 Polyphagia, 670 Polyribosomes, 124, 124 Polysaccharides, 60, 62t, 1005 Polyspermy, 1105 Polysynaptic reflex arc, 504, 505 Polythelia, 197 Polyuria, 670, 919 Pons, 515, 522, 523, 524, 525, 548t–555t control of autonomic function, 577 respiratory control in, 858, 869, 870 Pontine respiratory group, 869, 870 Popliteal lymph nodes, 810, 819 Popliteal region, 32, 302, 304 Popliteal surface of femur, 268, 269 Porta hepatis, 974, 975, 977 Portal systems as circulatory route, 757, 758 hepatic, 790t, 791 hypophyseal, 639, 640 Port-wine stain, 189 Positive feedback loops in decompensated shock, 771 in fibrinolysis, 707, 707–708 in gastric function, 972, 973 in hypertension, 802 in hypothermia, 1027–1028 in labor and childbirth, 18–19, 19, 1091 in sickle-cell disease, 690 in water conservation, 915, 916 Positive feedback theory of labor, 1091 Positive inotropic agents, 740, 742–743, 743t Positive nitrogen balance, 1009 Positive selection, 833 Positive water balance, 936, 936t Positron emission tomography, 23, 24, 527, 538, 557, 557 Postabsorptive state, 1023t, 1024 Postcapillary venules, 756 Postcentral gyrus, 513, 541, 542, 588, 609, 609 Posterior (position), 29, 30, 31, 31t, 32 Posterior chamber of eye, 614, 614 Posterior mesentery, 36 Posterior nasal apertures, 856, 858 Postganglionic fibers, 564, 564, 567, 568, 728, 741 Postherpetic neuralgia, 494 Postovulatory phase, 1080, 1081, 1082, 1083t Postpartum period, 1093 Postsynaptic neuron, 460, 460 Postsynaptic potentials, 464, 464, 466, 466–467 Posttetanic potentiation, 471 Posttranslational modification, 126, 127 Post-traumatic infarction, 507 Potassium, 939–940 atomic structure of, 44 deficiency of, 666, 742, 743, 939, 940, 948t digestion and absorption of, 989 excitation of hair cells, 602–603 I-36 sal78259_index.indd I-36 11/19/10 1:43 PM Potassium (continued) functions, 939, 939 heart rate and, 742 homeostasis, 938, 940 imbalances, 939, 940, 946 muscle fatigue and, 424 in resting membrane potential, 453, 453 sources and requirements, 1010t tubular reabsorption of, 911, 911 Potassium channels, 455–456, 456, 730, 731 Potassium chloride, 47t, 949 Potential energy, 56 Potential spaces, 37, 864, 866, 872, 1067, 1068 Power stroke, 90, 90, 412, 415 PP cells, 651 PQ segment of P wave, 731, 732 Precentral gyrus, 513, 541, 542, 543 Precipitation of antigens, 840 Preeclampsia, 1095t Preembryonic stage, 1103, 1106–1109, 1106t Preembryos, 1133 Preformed water, 932, 932 Prefrontal cortex, 538, 539 Preganglionic fibers, 564, 564, 567, 567–568, 728 Pregnancy, 1086–1089 adjustments to, 1088–1089 disorders of, 919, 1095t, 1108 folic acid requirements, 482 hormones of, 1087–1088, 1088t iron metabolism, 687 lordosis in, 252, 252 prenatal development, 1087 puerperium, 1093 Rh incompatibility and, 693–694, 695 salt craving in, 939 total metabolic rate and, 1025 weight gain in, 1089, 1090, 1090t Prehensile hands, 11, 11 Preload, 742 Premature infants, 874, 1120 Premature ventricular contraction, 729, 733, 733t Premenstrual syndrome, 646 Premolars, 959, 960, 961 Premotor area, 541, 541 Pre-mRNA, 122 Prenatal development, 145, 214 adrenogenital syndrome in, 669, 670 embryonic stage, 1106t, 1109–1111, 1116 fertilization, 1104, 1104–1105 fetal development, 1114, 1115–1117, 1118, 1118t preembryonic stage, 1106–1109, 1106t prenatal nutrition, 1108, 1111, 1112, 1113, 1113–1114, 1114t sexual differentiation, 1037–1038, 1038, 1039 trimesters, 1106, 1106t Preprohormone, 657 Preproinsulin, 657 Prepuce, 392, 1045, 1046, 1047, 1066, 1071, 1072 Prepuce (foreskin), 1046, 1047 Presbyopia, 618t, 1127 Pressoreceptors, 741 Pressure, 734 Pressure gradients, 769, 866 in alveolar gas exchange, 879, 880, 881 in blood flow, 734–736, 735, 736 Pressure points, 801, 801 Pressure sores, 173 Presynaptic inhibition, 468, 468, 590, 590 Presynaptic neuron, 460, 460 Pretectal region of midbrain, 616 Primary active transport, 96, 97, 97, 101t Primary cilium, 90, 91 Primary germ layers, 145, 1103 Primary gustatory cortex, 541, 541 Primary hypertension, 802 Primary marrow cavity, 215–216, 216 Primary motor area, 541, 542 Primary olfactory cortex, 541, 541, 595, 595 Primary ossification center, 215, 216 Primary response to antigens, 841 Primary sensory cortex, 540 Primary sex organs See Gonad(s) Primary somatosensory cortex, 541, 542 Primary spermatocytes, 1052, 1053 Primary structure of protein, 67, 68 Primary vesicles, 514, 517 Primary visual cortex, 540, 541, 627 Primates, adaptations of, 10–11, 11 Prime mover, 317, 318 Priming, 1013, 1013 Primipara, 1091 Primitive groove, 1108, 1109 Primitive gut, 1109, 1110 Primitive streak, 1108, 1109, 1116 Primordial germ cells, 1052 Principal cells, 913 Principal piece of sperm, 1053, 1054 Proaccelerin, 706, 707t Procarboxypeptidase, 979, 979, 979t Procedural memory, 472, 538 Processes of bone, 236t, 237 alveolar, 247, 249 anterior clinoid, 244, 245 bifid, 254 condylar, 249 coracoid, 261, 261, 299 coronoid, 249, 262, 262, 263 frontal, 247 mastoid, 238, 239, 243, 243 odontoid, 253–254, 254 olecranon, 262, 262–263, 389, 393, 394 orbital, 247 palatine, 238, 239, 248 pterygoid, 245, 245 spinous, 252, 253, 255, 255 styloid, 238, 239, 243, 243, 262, 262, 263, 298, 394, 395 superior articular, 252–253, 253 temporal, 238 transverse, 252, 253 xiphoid, 257, 258, 388 zygomatic, 238, 243, 243, 247 Procoagulants, 703, 705, 707t Proconvertin, 706, 707t Products, 56 Progeria, 1130, 1130 Progesterone, 651, 652, 654t, 657, 1084, 1089 action of, 661 electrolyte balance and, 938–939 permissive effects of, 664–665 in pregnancy, 1087, 1087–1088, 1088t role in puberty, 1076 secretion of, 641 uterine contractility and, 1090 Programmed cell death, 106, 173 Prohormone, 657 Proinsulin, 657, 658 Projectile vomiting, 971 Projection pathways auditory, 600, 605, 606 gustatory, 593 olfactory, 594, 595 pain, 588–589, 589 sensory, 584 somatosensory, 587–588 vestibular, 609, 609 visual, 625–627, 626 Projection tracts, 531, 532 Prolactin, 128, 128, 637t, 639, 641–642, 641t, 642 hormone interactions, 665 milk synthesis and, 1093–1094, 1094 Prolactin-inhibiting hormone See Dopamine Pronation, 29, 29–30, 282, 293–294, 294 of foot, 297 of forearm, 350t, 351 Pronuclei, 1105, 1105 Proopiomelanocortin, 642 Prophase, 119 of meiosis, 1050, 1051, 1052 of mitosis, 119, 132, 133, 1050 Proplatelets, 703, 703 Proprioception, 485, 493, 540, 541, 546, 547 Proprioceptive signals, 588 Proprioceptors, 501–502, 502, 544, 585 effects on cardiac output, 741, 743 stimulated by exercise, 887 tendon organs, 505, 505 Proseminogelin, 1054 Prosencephalon, 514, 517 Prosopagnosia, 538 Prostacyclin, 666, 667, 704 Prostaglandins, 666, 667, 828t effect on vasomotion, 762 roles of, 667t of semen, 1054 Prostate gland, 392 anatomy of, 1045, 1046 diseases of, 139, 1047 Prostate-specific antigen, 1047, 1054 Prostatic fluid, 1054 Prostatic urethra, 921, 922, 1045, 1045 Prostheses, 307–308, 308 Prosthetic group, 67 Proteases, 173, 985, 986 Protein(s), 59, 66–69, 1004t, 1009–1010 See also specific proteins abnormal, 1131 amino acids and peptides, 66, 66–67, 67t antimicrobial, 823–825 complete/incomplete, 1009 conjugated, 67, 67 contractile, 405 deficiency of, 683, 683, 760, 768, 1120 dietary sources, 1009 digestion of, 985, 986, 987 fibrous or globular, 67, 1009 functions of, 68–69 membrane proteins, 85, 85–86, 86, 96 in muscle fibers, 405–406, 406 nitrogen balance and, 1009–1010 plasma membrane and, 85, 85–86, 86, 91 regulatory, 128, 128, 405, 407t requirements, 1009 structure of, 66, 67, 68, 69 synthesis of (See Protein synthesis) Protein buffer system, 943 Protein folding, 50 Protein kinase, 661, 663 Protein-sparing effects, 644, 949, 1006, 1009 Protein synthesis, 121, 122–126 amino acids in, 1023 compounds other than proteins, 128–129, 129 gene regulation, 127–128, 128 I-37 sal78259_index.indd I-37 11/19/10 1:43 PM processing and secretion, 126–127, 127, 128t role of growth hormone in, 644 transcription, 122, 123, 126 translation, 122–123, 123–126, 125–126 Proteinuria, 905 Proteoglycans, 61, 62t, 155, 904 Prothrombin, 682t, 705, 706, 707t Prothrombin activator, 705, 706 Protofilaments, 102, 104 Proton donors, 54 Proton pumps, 1016–1017, 1017 Protons, 44 Protoplasm, 79 Protraction of joint, 292, 293 mandible, 294, 296, 298, 328t scapula, 344, 344t Protuberance of bone, 236t, 239, 244, 248 Provitamins, 1011 Proximal (direction), 30–31, 31t Proximal convoluted tubule, 901, 902, 902, 903, 910–913 transport maximum, 912, 912 tubular reabsorption, 910–911, 911 tubular secretion, 905, 913 uptake by peritubular capillaries, 911–912, 912 “Prune fingers,” 185 Pseudogenes, 593 Pseudopods, 98, 98, 703, 703 Pseudounipolar neurons, 444, 445 Psoriasis, 198t Psychopharmacology, 578 Psychosomatic effects, Ptosis, 434, 434 p53 tumor-suppressor gene, 138 Pubarche, 1075 Puberty endocrine control of, 1048–1049, 1049 female, 1075–1076 male, 1047–1049 premature onset of, 669 role of leptin in, 653, 654t Pubic region, 32 Pubic symphysis, 265, 266, 266, 282, 283, 392, 1066 Pudendum (vulva), 1071, 1072 Puerperium, 1093 Pulled groin, 374 Pulled hamstrings, 374 Pulmonary barotrauma, 890 Pulmonary circuit, 715, 716, 772, 773, 782t, 1119 Pulmonary compliance, 874 Pulmonary disorders, 887, 888t, 890 acute rhinitis, 888t adult respiratory distress syndrome, 888t asthma, 843, 844, 876 atelectasis, 872, 874 black lung disease, 743 chronic bronchitis, 743, 888, 1128 COPD, 743, 864, 881, 888–889, 1128 decompression sickness, 890 embolism, 709 emphysema (See Emphysema) hyaline membrane disease, 874, 1120 lung cancer, 879, 889, 889–890 obstructive, 876, 1128 oxygen imbalances, 887–888 pneumonia, 888t pneumothorax, 872 respiratory infections, 1128 restrictive, 876 role in cardiac output, 743 scuba diving as cause, 890 sleep apnea, 888t smoking and, 889, 889–890 tuberculosis, 879, 888t Pulmonary edema, 739, 739, 768 Pulmonary elasticity, 872, 874 Pulmonary hypertension, 739 Pulmonary obstruction, 1128 Pulmonary surfactant, 865–866, 874 Pulmonary valve, 722, 735 Pulmonary ventilation, 866–877 aging and, 1128 alveolar ventilation, 874–875 control of pH and, 943 measurement, 875, 875–876, 875t, 876 neural control of, 868–871 pressure, resistance, and airflow, 871–874, 871t in respiratory compensation, 947 respiratory muscles, 867, 868 variations in rhythm of, 876, 877t Pulp cavity, 960, 960 Pulp of tooth, 960, 960 Pulsatile blood flow, 759 Pulse pressure, 759 Pumps, 86 Punnett square, 135, 135 Pupil, 613, 613 constriction of, 617, 617 innervation of, 616 Purines, 115–117, 116 Purkinje cells, 439, 526, 543 Purkinje fibers, 727, 728 Pus, 701, 830, 918 Putamen, 533, 533 P wave, 731, 732 Pyelitis, 921 Pyelonephritis, 921 Pyloric glands, 967, 968 Pyloric region, 965, 966 Pyloric valve, 315, 316 Pylorus, 965, 966 Pyramid(s), 486, 487 of medulla oblongata, 515, 522, 523 renal, 899, 899 Pyramidal cells, 444, 466, 531–532, 533, 543 Pyramidal decussation, 522, 523 Pyramidal tracts, 486 Pyrexia See Fever Pyridoxine, 1011t Pyrimidines, 115–117, 116 Pyruvic acid, 72–73, 73, 1013, 1013–1015, 1015 Pyuria, 918 Q QRS complex, 731, 732 Quadrants, abdominal, 31, 33 Quadrilateral muscles, 315 Quadriplegia, 507 Quaternary structure, 67, 68 Quickening, 1118t Quiescent period, 739 Quiet respiration, 867, 868, 869, 876 R Rabies (hydrophobia), 506t Radial abduction, 296, 296 Radial flexion, 295–297, 296 Radial notch, 262, 263 Radiation See also specific types bone contamination due to, 211 heat loss due to, 1026 Radical (R) group, 66 Radical mastectomy, 1075 Radioactivity, 45, 45–46 Radiography, 23, 23–24 Radioisotopes, 45 Radiology, Radium “tonics,” 211 Radon, 46 Ramón y Cajal, Santiago, 452, 460, 466 Ramus (rami) communicating, 493, 493, 565, 567, 567 gray, 567, 567 white, 567, 567 of ischium, 265, 266, 267 of mandible, 248, 249 of pubis, 265, 266, 267 of spinal nerves, 319, 491, 493, 493 Range of motion, 287–288 RANKL, 222–223 Rapid ejection, 737, 738 Rapid eye movement (REM) sleep, 537 Rapid ventricular filling, 737, 738 ras oncogene, 138 Raynaud disease, 577t RBC count, 686, 689 Reactants, 56, 71 Reaction cascade, 705, 707 Reaction products, 60, 70, 424 Reaction rates, 57–58 Reactive hyperemia, 762 Receptive field, 584, 584 Receptive-relaxation response, 432 Receptor(s), 18 See also specific types for hormones, 637, 660–663 membrane proteins as, 85, 86 Receptor-mediated endocytosis, 99, 99–100, 101t, 766, 815 Receptor potentials, 583 Recessive alleles, 135 Reciprocal inhibition, 503, 504 Recognition phase of cellular immunity, 834–835 of humoral immunity, 837, 838, 839 Recommended daily allowances (RDAs), 1004–1006, 1009, 1009t, 1010t Recovery stroke, 90, 90, 412, 415 Recruitment, 420, 420, 427, 469 Rectal valves, 990, 991 Rectouterine pouch, 1069 Rectum, 387, 392, 990, 991, 1066 Rectus sheath, 335–337, 335t, 383 Red area of lips, 958 Red blood cells See Erythrocytes Red bone marrow, 213, 214, 392, 810 aging and, 1128 histology of, 816, 816 leukocyte storage in, 701 as lymphatic organ, 815–816, 816, 832, 832 megakaryocytes in, 703, 703 sinusoids of, 703, 703, 816, 816 Red-green color blindness, 624, 625 Red pulp of spleen, 821, 821 Reduced ejection, 737, 738 Reducing agent, 58 Reduction, 58, 58t Reduction division, 1050 Reductionism, 13–14 Reference man, 16 Reference woman, 16 Referred pain, 588–589, 589 Reflex(es) See also specific reflexes baroreflexes, 18, 18, 563, 563, 742, 762–763, 763 chemoreflexes, 742, 762, 763 conditioned, 501 hyperreflexia, 507 inflation reflex, 870–871 involuntary, 500–501 knee-jerk (patellar) reflex, 363, 503–504, 504 somatic (See Somatic reflexes) stimuli and, 500 vagovagal or myenteric, 957 visceral, 441, 501, 562–563, 563 Reflex arc, 501 autonomic, 563, 563 contralateral, 504, 505 I-38 sal78259_index.indd I-38 11/19/10 1:43 PM Reflex arc (continued) intersegmental, 504, 505 ipsilateral, 504, 505 in labor, 1091 monosynaptic, 503, 504 polysynaptic, 504, 505 Reflux, 735 Refraction, 616, 616 Refractive index, 616, 616 Refractory period, 457, 457, 458, 1056, 1058 absolute, 457, 457, 469, 730, 731 relative, 457, 457 Regeneration, 172, 174 Regeneration tube, 451, 451 Regenerative cells, gastric, 967 Regulatory proteins, 128, 128, 405, 407t Regulatory T cells, 834, 842t Rejection responses, 593 Relative atomic mass, 45 Relative refractory period, 457, 457 Relaxation of muscle fibers, 416, 417 Relaxin, 1088, 1088t Release factor, 125 Releasing hormones, 639, 640–641, 640t Remodeling phase in fracture healing, 226, 226–227 in tissue repair, 173, 174 Renal area of spleen, 821, 821 Renal autoregulation, 907–908, 908 Renal calculi (kidney stones), 669, 921 Renal clearance, 920 Renal columns, 899, 899 Renal compensation, 947 Renal corpuscle, 901–902, 902 Renal failure acute or chronic, 924t anemia due to, 689, 689t in diabetes mellitus, 670, 671 hypertension and, 759 in spina bifida, 482 transfusion reaction and, 692 Renal fraction, 899 Renal function tests, 919–920 Renal insufficiency, 897, 925, 925 Renal papilla, 899, 899 Renal parenchyma, 899, 899 Renal pelvis, 899, 899 Renal pyramids, 899, 899 Renal tubules, 900, 902, 903, 904, 930 blockage of, 925 distal convoluted tubule, 901, 902, 903, 913–914 epithelia of, 149, 149t PCT (See Proximal convoluted tubule) reabsorption in (See Tubular reabsorption) secretion of hydrogen ions, 943, 944 Renin, 652, 654t, 904, 908, 909 Renin-angiotensin-aldosterone mechanism, 908, 909, 909, 938 Replication errors, 131 Replication fork, 130, 130 Replicative senescence, 1130 Repolarization of membrane, 411, 455, 456 in myocardial contraction, 729, 730, 732, 732–733 Reposition of joint, 297 Representational hemisphere, 545 Reproduction, 16 Reproductive cycle, 1077 Reproductive system, 39 abnormalities of sexual development, 1037–1038 descent of gonads, 1038, 1040, 1040 embryonic development of, 1038, 1039 female (See Female reproductive system) interactions with other systems, 1098 male (See Male reproductive system) senescence, 1129 sexual differentiation, 1037, 1038, 1039 Reproductive technology, 1132–1133, 1133 Reserve cartilage zone, 217, 218, 218 Residual volume, 874–875 Resistance, 734 Resistance arm, 284, 285, 286 Resistance exercise, 1129 Resistance stage of GAS, 665–666 Resistance to airflow, 874 Resistance vessels See Arteries, generally Resolution (microscopes), 81, 82 Resolution phase female, 1085, 1086 male, 1056, 1058 Resorption bay, 210, 210 Respiration, 333t, 855, 870 aerobic (See Aerobic respiration) breathing (See Pulmonary ventilation) exercise and, 887 forced or quiet, 867, 868, 869, 876 Kussmaul, 671, 877t, 886 muscles of, 333t–334t, 334 placenta and, 1114t stretch receptors in, 870–871 Respiratory acidosis, 886, 889, 946, 946t Respiratory alkalosis, 886, 946, 946t Respiratory arrest, 877t Respiratory burst, 823 Respiratory capacities, 875–876, 876 Respiratory centers, 522, 870 Respiratory chemoreceptors, 1089 Respiratory compensation, 947 Respiratory crisis, 844 Respiratory cycle, 867 Respiratory disorders See Pulmonary disorders Respiratory distress, 739–740 Respiratory enzyme complexes, 1016–1017, 1017 Respiratory epithelium, 857 Respiratory membrane, 865, 866, 879, 881 Respiratory mucosa, 593 Respiratory system, 37, 38, 854–891 See also Pulmonary ventilation adjustments to pregnancy, 1089 anatomy of, 855–866, 856 control of pH, 943 disorders of (See Pulmonary disorders) excretion by, 898 functions of, 855 gas exchange (See Gas exchange) gas transport (See Gas transport) interactions with other systems, 891 neonatal adaptations, 1119, 1120 senescence, 1128 Respiratory volume, 875, 875, 876 Responsiveness, 16 Restenosis, 745 Resting membrane potential, 97, 411, 453, 453, 456, 937 Restrictive lung disorders, 876 Retching, 971 Rete testis, 1043, 1044 Reticular activating system, 526 Reticular cells, 815, 816, 817, 817, 842t Reticular epithelial cells, 816, 817, 832 Reticular fibers, 155, 815, 819 Reticular formation, 486, 522, 524, 525–526, 526 role in breathing, 869, 869–870 role in equilibrium, 609, 609 Reticular layer of dermis, 186, 186, 187t Reticular tissue, 155, 157, 157t Reticulocytes, 686, 686–687 Reticulospinal tracts, 484t, 485, 486, 525, 544 Retina, 613, 613, 614–615 anaxonic neurons of, 445 histology, 619 sensory transduction in, 617, 619, 619–623, 620 Retinacula, 317 Retinal (retinene), 620, 621 Retinol See Vitamin A Retraction of joint, 292, 293 of mandible, 294, 296, 328t scapula, 344, 344t Retrograde amnesia, 538 Retrograde transport, 445 Retroperitoneal (position), 36, 36, 957 Retroviruses, 845 Reuptake, 465 Reverberating circuit, 470, 470, 471 Reverse chloride shift, 885 Reverse osmosis, 93–94 Reverse transcriptase, 845 Reversible chemical reactions, 57 Reversible local potentials, 454, 454t Reye syndrome, 827 Rh blood group, 693–694, 695 Rheumatic fever, 735, 844 Rheumatism, 306t Rheumatoid arthritis, 307, 307 Rh immune globulin, 694 Rhinitis, 888t Rhodopsin, 619, 620, 621 Rhomboencephalon, 514, 517 Rhythm method, 1096 Riboflavin, 1011t Ribonuclease, 979, 979t Ribonucleic acid See RNA Ribose, 71, 72 Ribosomal RNA (rRNA), 119, 123 Ribosomes, 83, 104, 105, 105, 109t, 123 “RICE” therapy, 374 Rickets, 211, 223 Rider’s bones, 374 Right colic flexure, 990, 991 Rigor mortis, 416 Ringer’s lactate solution, 949 RNA, 73 DNA compared, 120t messenger (mRNA), 119, 122, 644 ribosomal (rRNA), 119, 123 structure and function, 116, 119 transfer (tRNA), 119, 122–123, 123 RNA polymerase, 122 Rods, 619, 619–620, 620 Roentgen, William, 23 “Roid rage,” 74 Root(s) of hair, 190, 191 of lung, 862, 863 of nerve plexuses (See Nerve plexuses) of nose, 381 of penis, 392, 1045, 1046, 1047 of spinal nerves, 481, 483, 490–491, 492, 495, 496, 496t, 498, 499 of tongue, 959, 959 of tooth, 960, 960 Root canal therapy, 960, 961 I-39 sal78259_index.indd I-39 11/19/10 1:43 PM Rosacea, 198t, 1125 Rostral (direction), 30, 31t, 512 Rotation, 292–293, 294 axes of, 288, 289 embyronic limb rotation, 271, 271, 295 of head, 331t hip and thigh, 361, 362t lateral or medial, 292, 293, 344, 344t of trunk, 294, 295 Rotator cuff, 299, 300, 347, 349, 349t Rotator cuff injury, 349t, 374 Rough endoplasmic reticulum, 83, 104, 105, 109t, 126, 127 Round window, 599, 599 Rubella, 1121 Rubrospinal tracts, 486, 525 Ruffini corpuscles, 586, 587, 587t Ruffled border of osteoclast, 210, 210, 220 Rugae gastric, 966, 967 of urinary bladder, 921, 922 vaginal, 1066, 1070–1071, 1085 Rule of eights, 45 S Saccule, 599, 605–607, 607 Sacral hiatus, 256, 257 Sacral region, 32, 479, 480 Sacral vertebrae, 256, 257, 266 Sacrificial bonds, 211 Sagittal plane, 30, 30, 288, 289 Saliva, 933, 961 Salivary amylase, 71, 961, 962, 984 Salivary glands, 169, 570, 571, 961–962, 962, 963 Salivation, 576, 962 Saltatory conduction, 459, 460 Salt intake, 1010–1011 Salty tastes, 591–592 Sample size, Sanger, Frederick, 673 Sarcolemma, 403, 404, 407t, 409, 409 in rigor mortis, 416 voltage-regulated ion gates in, 412, 413 Sarcomas, 138, 211, 227t, 845 Sarcomeres, 406, 407, 407t, 1126 Sarcoplasm, 403, 404, 407t Sarcoplasmic reticulum, 404, 404, 407t, 416, 431, 726 Satellite cells, 403–404, 446t, 448 Satiation, 933, 933–934 Satiety (sensation), 1001–1002 Satiety center, 529, 530 Saturation, 95, 660 Scala media (cochlear duct), 599, 599–600, 600 Scala tympani, 599, 599, 600 Scala vestibuli, 599, 599, 600, 602 Scalp, 323, 324t, 325, 382 Scanning electron microscope (SEM), 81 Scapular region, 32 Schizophrenia, 556t Schleiden, Matthias, 6, Schlieren photography, 1026, 1026 Schwann, Theodor, 6, 9, 79, 995 Schwann cells, 409, 409, 446t, 448, 450, 450, 488 Sciatica, 497 Scientific method, 7–9 Sclera, 613, 613 Sclerosis, 447 Scoliosis, 252, 252, 433 Scotopic (night) vision, 620, 620, 623, 624 Scrotum, 384, 385, 392, 1041, 1041–1042, 1042 Scuba diving, 890 Seasonal affective disorder (SAD), 646 Sebaceous glands, 195, 196, 197t, 1047 Seborrheic dermatitis, 198t Sebum, 196 Secondary active transport, 96, 96–97, 98, 101t, 910 Secondary hypertension, 802 Secondary marrow cavity, 216, 216 Secondary ossification center, 216, 216 Secondary response, 841 Secondary sex characteristics, 1036 Secondary sex organs, 1035 Secondary spermatocytes, 1052, 1053 Secondary structure of protein, 67, 68, 126 Secondary tympanic membrane, 599, 599 Secondary vesicles, 514, 517 Second-class lever, 286, 286, 287 Second-degree burns, 199, 200 Second heart sounds, 736 Second messengers, 86–87, 87 Second-messenger systems cAMP system, 594–595, 741 membrane proteins as, 85 in nonspecific defense, 824 for peptides and catecholamines, 660, 661–662, 662, 663 Second polar body, 1077, 1078 Secretin, 970, 972, 973, 974, 979–980 Secretion See specific glands and substances Secretory granules, 461 Secretory vesicles, 83, 106, 127, 127, 128, 128, 978, 978 Sectioning, 145, 145–146, 146 Sedentary behavior, 764, 764, 765, 802 Segmentation, 983, 983 Segments of neuron, 443, 450 Segments of spinal cord, 479, 480 Selectins, 828t, 829 Selection pressures, 10 Selection window, 1080 Selective permeability, 91 Selective serotonin reuptake inhibitors, 578 Selenium, 48, 1010t Self-antigens, 844 Self-tolerance, 833 Sella turcica, 238, 239, 244, 246 Selye, Hans, 665 Semen, 1046, 1054, 1059t Semicircular ducts, 607–608, 608 Semiconservative replication, 130, 130 Semilunar valves, 722, 735–736, 736 Seminal vesicles, 392, 1045, 1046 Seminiferous tubules, 651, 652, 1034, 1042, 1043, 1044 Seminogelin, 1054 Senescence, 1124–1131 circulatory system, 1127–1128 digestive system, 1129 endocrine system, 1127 evolution and, 1129–1131 exercise and, 1129 immune system, 1128 integumentary system, 1125–1126, 1126 muscular system, 1126–1127 nervous system, 1127 reproductive system, 1129 respiratory system, 1128 of sense organs, 1127 skeletal system, 1126 theories of, 1129–1131 urinary system, 1128–1129 Senile atrophy, 173 Senile plaques, 473, 473, 1127 Sensation, 540–541, 583 general senses, 530, 541, 541, 542 special senses, 530, 540–541, 541 Sense organs, 582–628, 583 chemical senses, 591–595 general senses, 585–591, 586, 587t hearing and equilibrium, 596–609 senescence of, 1127 sensory receptors, 583–585 skin as, 181–182 vision (See Vision) Sensible water loss, 933 Sensorineural deafness, 605 Sensory adaptation, 585 Sensory coding, 468, 603, 604 Sensory division of PNS, 441, 441 Sensory homunculus, 541, 542, 588 Sensory nerves, 489, 522, 547 Sensory (afferent) neurons, 442, 442, 449 Sensory projection, 584 Sensory receptors, 583–585, 584 See also specific types Sensory transduction, 617, 619, 619–623, 620 Septal defects, 744t Septicemia, 709t Septic shock, 770 Septum (septa) of exocrine gland, 168, 168 interatrial, 718, 719–721 intermuscular, 316, 316 interventricular, 718–719, 719–721 median, 1041, 1041–1042, 1046, 1047 nasal, 247, 856, 856, 858 of testes, 1042, 1043 Serine protease, 1047, 1054 Serosa See Serous membranes Serotonin, 461, 462, 463t, 704 Serous fluid, 170, 171 Serous glands, 169 Serous layer of pericardial sac, 716, 718 Serous membranes, 35, 36, 37, 170, 171 of digestive tract, 955, 956 peritoneum, 36, 36, 37 pleurae, 35, 35–36 Sertoli cells, 651, 652, 1043, 1044 Serum, 681 Serum cholesterol level, 1007 Serum lipoproteins, 1007–1008, 1008 Servetus, Michael, Sesamoid bones, 234, 263, 264 Set point, 17, 1001 Severe combined immunodeficiency disease (SCID), 845, 845 Sex chromosomes, 134, 1036–1037, 1037 Sex-influenced traits, 193 Sex-linked traits, 137, 137 Sex pheromones, 196 Sex steroids, 649, 655 bone growth and, 224 nitrogen balance affected by, 1009–1010 Sexual cycle, 1077, 1079–1084 menstrual cycle, 1081, 1082–1084, 1084 ovarian cycle, 1080–1082, 1080–1082, 1083t Sexual differentiation, 1065, 1066 Sexual dimorphism of pelvis, 267, 268, 268t Sexual intercourse AIDS transmitted through, 846 female sexual response, 1085, 1086, 1103 male sexual response, 1055–1058 anatomical foundations of, 1046, 1055 excitement and plateau, 1055, 1056, 1057 I-40 sal78259_index.indd I-40 11/19/10 1:43 PM Sexual intercourse (continued) orgasm and ejaculation, 1056, 1057–1058 resolution, 1056, 1058 treatment of erectile dysfunction, 1057, 1057 role of hypothalamus in sexual response, 530 sexually transmitted diseases, 1058, 1060, 1096 Sexually transmitted diseases, 1058, 1060, 1096 See also specific diseases Shaft of clitoris, 1085 of hair, 190, 191 of penis, 392, 1045, 1046 of ribs, 258, 258, 259 Sharpey fibers, 208 Shear stress, 762 Shell temperature, 1025–1026 Shingles, 494 Shinsplints, 374 Shivering thermogenesis, 1027 Short association fibers, 531 Short bones, 208 Short reflexes, 957 Short-term energy, 424 Short-term memory, 470, 471, 1127 Short-wavelength cones, 623, 625 Shoulder See also Upper limb dislocations, 300 humeroscapular joint, 259, 279, 288, 290, 299, 299–300 muscles acting on, 343, 344t–345t Shunts, 1114, 1115 Sickle-cell disease, 131, 137, 690, 690 Sickle-cell trait, 690 Sievert (Sv), 46 Sigmoid colon, 391, 392, 572 Sigmoidoscope, 990 Signal cessation, 465 Signal conduction in nerve fibers, 457–460 conduction speed, 450, 459 myelinated fibers, 458–460, 459 saltatory, 459, 460 unmyelinated fibers, 457–458, 458 Signal peptides, 657 Simple diffusion, 91–92, 92, 101t Simple epithelia See Epithelium Simple exocrine gland, 169, 169 Simple mastectomy, 1075 Simple microscope, Single covalent bonds, 48t, 49, 49 Single-nucleotide polymorphisms, 121 Single-unit smooth muscle, 430, 431 Sinoatrial node, 727, 727, 729, 733t, 741 Sinuses, 236t, 237 anal, 990, 991 carotid, 753–754, 754, 777 cavernous, 779t, 780 confluence of, 779t, 780 coronary, 719, 720, 724, 725 dural, 516–517, 518, 769 dural venous, 779t, 780 ethmoid, 240, 240, 246 frontal, 238, 240, 240, 246, 382, 858 lactiferous, 1073, 1074 maxillary, 240, 240 paranasal, 240, 240, 857 placental, 1112, 1113 renal, 899, 899 sagittal, 779t, 780 scleral venous, 614, 614 sigmoid, 779t, 780 sphenoid, 238, 240, 240, 246, 298, 858 straight, 779t, 780 subcapsular, 817, 819 transverse, 779t, 780 venous, 244 Sinusoids, 755, 756 hepatic, 790t, 791, 974, 976 of red bone marrow, 703, 703, 816, 816 Sinus rhythm, 729, 733 Sister chromatids, 119, 119 “SITS” muscles, 347, 349, 349t, 374 Situs inversus, 14 Situs solitus, 14 “Six pack,” 335, 335t, 336 Skeletal muscle(s) ACh receptors, 467 behavior of whole muscles, 418–422 cardiac and smooth muscle compared, 429t characteristics of, 402–403, 403 histology, 164, 165, 165t metabolism in, 423–427 muscle fibers (See Muscle fibers) nerve-muscle relationship, 408–411 of pharynx, 962–963 special circulatory route, 772 tolerance of anaerobic fermentation, 1014 Skeletal muscle pump, 757, 769, 770 Skeletal system, 37, 38, 207–209, 233–274, 235 adaptation for bipedalism, 12, 273–274, 273–274 adaptations for bipedalism, 12, 273–274, 273–274 appendicular skeleton, 234, 234t, 235 axial skeleton, 234, 234t, 235 bones (See under Bones) bone tissue and, 207–209 cartilage (See under Cartilage) interactions with other systems, 229 ligaments (See under Ligaments) pectoral girdle and upper limb, 259–263 pelvic girdle and lower limb, 265–272 senescence, 1126 skull (See Skull) vertebral column and thoracic cage, 250–259 Skene glands, 1072, 1072, 1085 Skin, 181–189, 182, 183, 186 See also Integumentary system artificial, 201 color of, 187–189, 188 dead skin, 185, 185 dermis, 181, 182, 183, 185–186, 186, 187t epidermis (See Epidermis) functions of, 181–182, 183, 222 barrier functions, 181, 822 endocrine functions, 652, 654t in nonverbal communication, 182, 183 role in facial expression, 182, 183, 185 as sense organs, 181–182 vitamin D synthesis, 181, 188 histology, 170 hypodermis, 181, 182, 186–187, 187t inflammation of, 827 innervation of, 500, 500 markings, 189 Skin cancer, 197–199, 199 basal cell carcinoma, 197, 198, 199 Kaposi sarcoma, 845 melanoma, 138, 198–199, 199 squamous-cell carcinoma, 197–198, 199, 899 ultraviolet radiation and, 188, 197, 1125 Skin disorders, 197–200, 198t acne, 198t, 1049 birthmarks, 189 burns, 199–200, 200 cancer (See Skin cancer) dermatitis, 198t eczema, 198t hives (urticaria), 848t pemphigus vulgaris, 167 psoriasis, 198t rosacea, 198t seborrheic dermatitis, 198t tinea, 198t Skin grafts, 175, 199, 201 Skin patch (contraceptive), 1097 Skull, 236, 237–240, 240–250, 241t See also Bones, specific adaptation for bipedalism, 274, 274 bones associated with, 249, 249 cavities of, 236, 240, 240 cranial bones, 239, 240, 241–247, 242 facial bones, 247–249 in infancy and childhood, 249–250, 250 sutural (wormian) bones, 234 Sleep, 529, 535–538, 536 Ondine’s curse, 870 regulation of, 526 Sleep apnea, 888t Sleep center, 530 Sleep disorders, 537, 870 Sleep paralysis, 536, 537 Sleep spindles, 536 Sliding filament theory, 9, 412, 415, 416 Slow axonal transport, 445 Slow block, 1105 Slow calcium channels, 730, 730, 731 Slow oxidative muscle fibers, 426, 426–427, 426t, 427t Slow pain, 588 Slow-wave sleep, 536, 537 Small intestine, 385, 391, 392, 980–983 endocrine functions of, 652–653, 654t epithelia of, 149, 149t, 150, 150t gross anatomy, 980, 980–981 intestinal motility, 983, 983 microscopic anatomy, 977, 981, 982, 983 secretions, 983 serous membranes of, 171 Small motor units, 408 Smallpox vaccine, 831 Small subunit (ribosomes), 123 Smears, 146, 162 Smegma, 1047 Smell (olfaction), 541, 541, 593–595, 594 aging and, 1127 anatomy of, 593 human pheromones, 595 physiology of, 593–595 projection pathways, 594, 595 respiratory system and, 855 role in taste, 592–593 Smoking, 889, 889–890, 1121 Smooth chorion, 1111 Smooth endoplasmic reticulum, 83, 104–105, 105, 109t, 1000 Smooth muscle, 428–433, 429, 430 of bronchi, 863 cardiac and skeletal muscle compared, 429t contraction and relaxation of, 431–432, 432 excitation of, 431 histology, 164, 165, 165t of lungs, 867 muscularis mucosae, 170, 171, 862, 955, 956 I-41 sal78259_index.indd I-41 11/19/10 1:43 PM myocyte structure, 430, 432 response to stretch, 432–433, 907, 1091 types of, 430, 431 of ureters, 921, 922 of uterine tubes, 1067 Smooth muscle tone, 432 Sneezing, 876 Sodium, 937–939 in action potentials, 455 atomic structure of, 44 control of pH and, 944 digestion and absorption of, 989 functions of, 937 homeostasis, 938, 938–939 imbalances, 939 ionization of, 47 in plasma, 682, 682t reabsorption of, 934, 934 in resting membrane potential, 453, 453 in signal conduction, 459, 459 sources and requirements, 1010–1011, 1010t water retention and, 763 Sodium bicarbonate, 47t, 937, 979 Sodium-calcium antiport, 989 Sodium channels, 455–456, 456, 730, 730 Sodium chloride, 47, 47t, 95, 910, 911 Sodium-glucose transporters, 96–97, 911, 911, 984, 985 Sodium-potassium pump, 453, 967 action of thyroid hormone and, 661 in carrier-mediated transport, 95, 97, 97 electrolyte balance, 937, 938 resting membrane potential and, 411 in tubular reabsorption, 910, 911 Soft callus, 226, 226 Soft keratin, 190 Soft palate, 856, 858, 959 Solubility, 879 Solubility product, 220 Solute, 52 Solutions, 52, 52, 53–54 Solvency of water, 51 Solvent, 52 Solvent drag, 767–768, 910, 911, 984, 985 Soma of neuron, 442, 443, 444 Somatic cells, 135 Somatic hypermutation, 839 Somatic motor fibers, 408 Somatic motor neurons, 483 Somatic nervous system, 441, 441, 564, 565t Somatic pain, 588 Somatic receptors, 501 Somatic recombination, 839 Somatic reflexes, 500–506 muscle spindle and, 501–502, 502 nature of, 500–501 role of spinal cord, 479 Somatic senses See General senses Somatomedins, 637t, 644, 652, 654t Somatosensory association area, 541, 542 Somatosensory nerves, 493 Somatosensory senses See General senses Somatostatin paracrine signaling, 666 in second-messenger system, 661 secretion of, 639, 640t, 641, 651, 654t Somatotopy, 541 Somatotropes, 642 Somatotropin, 637t, 641t, 642, 642 Somesthetic senses See General senses Somites, 1111, 1116 Sonography, 23, 24 Sörensen, Sören, 55 Sound, 596, 596–597, 860 Sound production, 857 Sour tastes, 592, 593 Spatial perception, 527 Spatial summation, 467, 467, 623, 624 Special senses, 530, 540–541, 541, 546, 585 Specific defense See Immunity Specific granules, 696 Specific gravity, 918, 919t Specific immunity, 830–833 antigen-presenting cells, 833, 834, 842t antigens, 831–832 B lymphocytes, 833, 842t forms of, 830–831, 842t T cells (See T lymphocytes) Specificity, 95, 660 Spectrin, 684 Speech and vocalization, 543, 545, 545, 557, 855 Sperm, 1034, 1035, 1050–1054 meiosis, 1050, 1051, 1052 migration of, 1103 production of, 1049 semen and, 1054, 1059t spermatogenesis, 1052, 1052–1053, 1053 spermatozoon, 1053, 1053–1054 storage of, 1043, 1044 Spermatic cord, 1041, 1042 Spermatic ducts, 1043, 1044–1045, 1045 Spermatids, 1052, 1053 Spermatogenesis, 1050, 1052, 1052–1053, 1053 Spermatogenic waves, 1053 Spermatogonia, 1052, 1052 type A, 1052, 1052–1053 type B, 1052, 1053 Sperm count, 1054 Spermicides, 1096–1097 Spermiogenesis, 1052, 1053 Sperm motility, 1054 Spheroidal cells, 80, 80 Sphincters, 164, 313 anal, 315, 316 external, 341t, 342, 990, 991, 992–993, 993 internal, 990, 991 esophageal, 963 hepatopancreatic (of Oddi), 975, 976, 977, 978 orbicularis oculi, 323, 324t, 325 physiological, 963 precapillary, 753, 753, 756, 772 pyloric, 965, 966, 970 urethral external, 315, 316, 341t, 342, 922, 922, 923, 923 internal, 922, 922 Sphygmomanometer, 734 Spicules, 212, 213 Spike, 457 Spina bifida, 482, 482 Spina bifida cystica, 482, 482 Spina bifida occulta, 482 Spinal cord, 382, 390, 391, 479–487, 513 compression by herniated discs, 253, 253 control of autonomic function, 577 cross-sectional anatomy, 481, 482–483 dorsal horn of, 590, 590 functions, 479 gray matter, 483 injury to, 507, 924 meninges of, 480–482, 481 neurons and glial cells of, 163, 163t role in equilibrium, 609, 609 spinal tracts (See Spinal tracts) surface anatomy of, 479–480, 480, 481 white matter, 483 Spinal curvatures, 251, 251 abnormal, 252, 252 of infants, 251, 252 primary or secondary, 251, 251 Spinal gating, 589–591, 590 Spinal meningitis, 506t Spinal nerve(s), 479, 481, 487–500 anterior divisions of, 496, 496t, 498, 499 cutaneous innervation, 500, 500 distal branches, 491, 492, 493, 493 general anatomy, 488–500, 489, 489t, 490 innervation of muscle, 319 meningeal branch of, 491, 492 nerve plexuses (See Nerve plexuses) nerve rootlets, 490–491, 493 posterior divisions, 496, 496t, 498, 499 proximal branches, 490, 490–491, 492 Spinal nerve disorders amyotrophic lateral sclerosis, 488, 488 assessing, 500, 500 crutch paralysis, 497 Guillain-Barré syndrome, 506t Hirschsprung disease, 572 neuralgia, 494, 506t, 556 paresthesia, 506t peripheral neuropathy, 506t poliomyelitis, 488 rabies (hydrophobia), 506t sciatica, 497 shingles, 494 spinal meningitis, 506t Spinal nerve route, 567, 568 Spinal shock, 507, 924 Spinal tap, 518 Spinal tracts, 483–487, 484, 484t ascending, 483, 485, 485–486, 588, 589 decussation of, 483, 485, 486, 487, 541, 547 descending, 486–487, 487 in white matter, 481, 482, 483 Spindle fibers, 119, 132, 133 Spine See Vertebral column Spine of bone, 236t, 237 ilium (See Bones, specific) ischium, 265, 267 scapula, 260, 261 Spinocerebellar tracts, 544 anterior, 484t, 485, 486, 522, 524 posterior, 484t, 485, 486, 522 Spinoreticular tract, 484t, 485, 486, 588, 589 Spinothalamic tract, 484t, 485, 486, 588, 589 Spiral (pectineal) line, 267, 269 Spiral organ, 600, 600 Spirometer, 875, 875, 1024–1025 Spirometry, 875, 875–876, 875t, 876 Splanchnic nerve route, 567, 568 Spleen, 385, 386, 810 as “erythrocyte graveyard,” 688, 821 as lymphatic organ, 820–821, 821 reticular tissue in, 157, 157t in sickle-cell disease, 690 Splenectomy, 821 Splenic flexure, 990, 991 Splenomegaly, 848t Split-skin graft, 201 Sponge (contraceptive), 1096–1097 Spongiocytes, 649 I-42 sal78259_index.indd I-42 11/19/10 1:43 PM Spongy bone, 161 conversion of, 214, 215, 217, 226, 226–227 diploe, 209, 209 histology, 206, 212, 213, 213 Spongy (penile) urethra, 922, 922, 1045, 1045 Spontaneous abortion, 1095t Spontaneous generation, 79 Sprains, 306t Spreads, 146 Squamous cell(s), 79, 80 Squamous-cell carcinoma, 197–198, 199, 889 Squamous epithelium simple, 147, 148, 149, 149t stratified, 148, 148, 151, 151t, 990 aging and, 1129 epidermis, 170 exfoliation of, 148, 153 vaginal, 1071 Squamous part of bone, 243, 243 SRY gene, 1037 St Martin, Alexis, 995, 995 Stab cells, 697 Stability, 313 Stadium of fever, 826–827, 827 Staircase phenomenon, 419, 420, 421 Standard international unit of radiation, 46 Starch, 60, 62t Start codon, 121–122 Starvation, 1025 Static equilibrium, 605 Statistical testing, 8–9 Steady state, 424 Steady-state response, 502 Stearic acid, 63 Stellate cells, 80, 80, 531, 533 Stem cells, 683 controversy over, 176 of epidermis, 183, 183 histology, 172 Stent, 745 Stereocilia, 600, 600 Stereoscopic vision, 11, 624–625, 625 Sterilization, surgical, 1097 Sternal angle, 257, 258 Sternal end of clavicle, 260, 260 Sternal region, 32 Steroid(s), 62t, 65, 65–66, 74 Steroidal anti-inflammatory drugs (SAIDs), 667 Steroid hormones, 655, 655t, 656 action of, 661 of pregnancy, 1094 synthesis of, 128–129, 129, 656–657, 657 Stigma, 1081 Stillbirth, 1121 Stimuli, 16, 442 adrenergic, 741 chemical, 454 effect on cardiac rhythm, 729 frequency of, 420, 420–421, 421 intensity of, 420, 420–421, 421, 469 in muscle twitch, 418–419, 419 reflexes and, 500 Stomach, 384, 385, 391, 965–974 actions of, 972, 973, 974 cephalic phase, 972, 973 gastric phase, 972, 973 intestinal phase, 972, 973, 974 anatomy of, 965, 966 digestion and absorption, 972 disorders of, 971, 971 endocrine functions of, 652–653, 654t gastric motility, 970 innervation and circulation, 965, 967 microscopic anatomy, 966, 967, 968 protection of, 972 removal of, 969–970 secretions, 967–970 chemical messengers, 970, 970t gastric lipase, 969 hydrochloric acid, 940, 967, 969, 969 intrinsic factor, 969–970 pepsin, 969, 969 vomiting, 970–972 Stop codons, 121–122 Strabismus, 434 Strains, 306t Stratified epithelia See Epithelium Stratum basale, 183, 183, 184, 187, 187t, 188 Stratum basalis, 1069, 1071, 1083, 1084 Stratum corneum, 182, 183, 184, 186, 187, 187t Stratum functionalis, 1069, 1071, 1083, 1084 Stratum granulosum, 183, 184, 187t Stratum lucidum, 183, 184, 187t Stratum spinosum, 183, 184, 187, 187t Streptokinase, 710 Stress, 643, 665–666, 743 adaptation to alarm reaction, 665 exhaustion stage, 665 resistance stage, 665–666 Stress fracture, 225 Stress proteins, 126 Stress-relaxation response, 432 Stretch, 431, 432–433, 907, 972, 973, 1091 Stretch marks, 186, 1089 Stretch receptors, 870–871, 923, 923 Stretch (myotatic) reflex, 503, 503–504 Striae, 186, 1089 Striated muscle muscle fiber, 164, 165, 402, 403 skeletal muscle, 406, 406–407, 407t, 428 Stroke (CVA), 771, 1129 Stroke volume, 737, 738, 739, 742–743, 743t Stroma, 168, 168 Strong acid, 942 Strong base, 942 Strontium-90, 45–46 Structural formulae, 48 ST segment of QRS complex, 731, 732 Studies in the Psychology of Sex (Ellis), 1055 Subarachnoid space, 480, 481, 482, 517, 518 Subclavian trunks, 813, 814 Subcostal line, 33, 33 Subcutaneous fat, 167 Subcutaneous fluid replacement, 949 Subcutaneous tissue, 181, 182, 186–187, 187t Subdural space, 517, 518 Sublingual salivary glands, 962, 962 Submandibular salivary glands, 962, 962 Submucosa of digestive tract, 992 Subpubic angle, 268, 268t Substance P, 461, 462, 463t, 590, 590, 970 Substantia nigra, 524, 525 Substrate, 69 Sucrase, 69–70, 70, 984 Sucrose, 60, 61, 62t, 984, 1005, 1006 Sudoriferous glands See Sweat glands Sugars, 1005 Sulcus (sulci) alar nasal, 856 of bone, 236t, 261, 262, 268 of brain, 513, 514 central, 513, 515, 530 cerebrum, 513, 515, 530 lateral, 513, 530, 531 parieto-occipital, 515, 530 of face, 381 gingival, 960, 960 of heart, 718, 719, 720 intertubercular, 261, 262 of spinal cord, 479, 481 superior palprebral, 381 terminal, 856, 959, 959 Sulfur, 1010t Sullivan, Louis Henri, 23 Summation, 467, 467, 468 Sunscreens, 198 Sunstroke (heatstroke), 1027, 1125 Suntanning, 197, 198 Superciliary ridge, 381 Superficial (position), 30, 31t Superficial perineal space, 341t, 342 Superior (position), 29, 30, 31, 31t Superior colliculi, 626, 626–627 Superior vertebral notch, 253, 254 “Superovulation,” 1132 Superoxide anions, 47, 823 Superoxide dismutase, 48 Supination, 29, 29–30, 282, 293–294, 294, 297, 350t, 351 Supporting cells, 591, 592, 600, 600 Supracondylar ridges, 262, 262 Supraorbital margin, 237, 242 Supraorbital notch, 242 Suprarenal glands See Adrenal glands Suprascapular notch, 260, 261 Suprasternal notch, 257, 258, 381, 388 Surface anatomy, 379–400 head and neck, 381, 382 importance of, 380 lower limb, 396–399 trunk, 383–393 upper limb, 393–395 Surface area of membrane, 92 Surface film of water, 51 Surface tension, 51, 874 Surfactant, 865–866, 874 Surgical neck of humerus, 261, 262 Surgical sterilization, 1097 Surrogacy, 1132–1133 Suspensions, 52, 53 Sustentacular cells, 651, 652, 1043, 1044, 1049 Sutural (wormian) bones, 234, 240 Sutures (synarthroses), 236, 238, 280, 281 coronal, 237, 238, 240, 242–243, 250 intermaxillary, 237–239, 247 lambdoid, 238–240, 242–243, 250 metopic, 249, 250 plane (butt), 280, 281 sagittal, 238, 240, 242–243, 250 serrate, 280, 280, 281 squamous (lap), 238, 242–243, 243, 250, 280, 281 Swallowing See Chewing and swallowing Sweat glands, 169, 195, 195–196, 197t apocrine, 193–197, 195, 197t eccrine, 195, 196 epithelia of, 152, 152t merocrine, 169, 170, 195, 196 Sweating, 1026, 1085 insensible perspiration, 196 profuse, dehydration and, 935, 935 water loss in, 932, 932 Sweet tastes, 592, 593 “Sweet tooth,” 1005 Swell body (erectile tissue), 857 Sympathetic nerve route, 567, 568 I-43 sal78259_index.indd I-43 11/19/10 1:43 PM Sympathetic nervous system, 441, 441, 616, 848, 965, 1127 anatomy of, 563–564, 565, 565–567, 567–568, 568t cardiac innervation, 728, 743 contrasting effects, 572 control of blood vessels, 762 control of glomerular filtration, 908–909 effects on target organs, 574t parasympathetic division compared, 571t regulation of postabsorptive metabolism, 1024 role in thermoregulation, 1027 senescence of, 1129 in voiding urine, 922, 923 Sympathetic tone, 563 Sympathoadrenal system, 568 Sympatholytics, 578 Sympathomimetics, 578 Symphyses, 282, 283 mental, 248 pubic, 265, 266, 266, 282, 283, 392 Symports, 95, 97, 101t, 910, 911 Synapses, 409, 409, 443, 444, 460, 460–465, 461 See also Neural integration adrenergic, 464–465, 465 axoaxonic, 460, 460 axodendritic, 460, 460 axosomatic, 460, 460 cessation of signal, 465 chemical, 461, 462, 466 cholinergic, 463–464, 464 GABA-ergic, 464 inhibitory, 464 neuromodulators and, 465 synaptic transmission, 463–465, 1126 Synaptic cleft, 409, 409, 411t, 465 Synaptic delay, 464, 466 Synaptic facilitation, 471 Synaptic knob, 409, 409–410, 411t, 412, 413, 443, 444 Synaptic plasticity, 471 Synaptic potentiation, 471 Synaptic remodeling, 446 Synaptic vesicles, 409, 410, 411t, 443, 444 in excitation, 412, 413 in smooth muscle, 429, 429 Synarthroses, 280, 280–282 Synchondroses, 282, 282–283 Syncope, 759, 770, 771, 1127 Syncytiotrophoblast, 1107, 1108, 1113 Syncytium, 1107 Syndesmoses, 280, 282 Synergist, 317, 318 Synergistic effects of hormones, 664 Synostoses, 280 Synovial fluid, 170, 283, 284 Synovial joints (diarthroses), 283–297 aging and, 1126 ball-and-socket, 288, 290 classification of, 288–291, 290 condylar (ellipsoid), 288, 290 general anatomy of, 283–284, 284, 285, 298, 304 gliding (plane) joints, 289–290, 290 hinge, 290, 290–291 as lever systems (See Lever systems) movements of, 291–297 abduction and adduction, 291, 293 circumduction, 292, 293 elevation and depression, 292, 293 flexion and extension, 291, 292 foot, 297, 297 hand and digits, 295–297, 296 head and trunk movements, 294, 295 learning strategies, 294 mandible, 294–295, 296 protraction and retraction, 292, 293 rotation, 292–293, 294 supination and pronation, 293–294, 294 pivot, 290, 291 saddle, 288–289, 290 Synovial membranes, 170, 171, 283, 284, 298, 302 Synovitis, 306t Synthesis phase in cell cycle, 131, 131 Synthesis reactions, 56, 57 Syphilis, 1060, 1121 Systemic circuit, 715–716, 716 appendicular region, 792–800 axial region, 773, 774, 775, 776–791 Systemic edema, 739, 740, 768 Systemic gas exchange, 880, 883, 883–884 Systemic lupus erythematosus, 844 Systole, 728, 730 Systolic pressure, 759, 759 T TA (Terminologia Anatomica), 20 Tachycardia, 740, 742, 1085 Tachypnea, 877t Tactile cells, 183, 184, 586, 586 Tactile (Meissner) corpuscles, 586, 587, 587t Tactile discs, 184, 586, 586, 587t Taenia coli, 990, 991 Tail of epididymis, 1043, 1044 of myofilament, 405, 405 of pancreas, 977, 978 of sperm (flagellum), 1053, 1053 of spermatozoon, 1053, 1054 Tamoxifen, 1075 Target cells action of thyroid hormone on, 661, 661 for hormones, 637, 660 responses to neurotransmitters, 572–575, 573, 574t, 575t sensitivity to hormones, 664, 664 Target organs for hormones, 637 negative feedback inhibition, 643–644, 644 sympathetic and parasympathetic effects on, 574t Tarsal glands, 610, 611 Tarsal plate, 610, 610, 611 Tarsal region See Ankle Tartar (calculus), 961 Taste (gustation), 541, 541, 591–593 aging and, 1127 anatomy of, 591, 592 projection pathways, 593 Taste buds, 591, 592, 958 Taste cells, 591, 592 Taste pores, 591, 592 Tay-Sachs disease, 448 T cells See T lymphocytes Tectorial membrane, 600, 600, 602 Tectospinal tract of medulla oblongata, 522 of spinal cord, 484t, 485, 486 Tectum, 486, 524, 525 Teeth (dentition), 246, 959–961, 960, 961 orthodontic appliances, 221 permanent v deciduous, 961, 961 tooth and gum disease, 961 Tegmentum, 524, 525 Telencephalon, 514, 517 Telogen phase of hair cycle, 191, 192, 193 Telomerase, 1130 Telomeres, 1130 Telophase meiosis, 1050, 1051 mitosis, 132, 133, 1050 Temperature, 71, 92, 431 of body (See Body heat) dehydration and, 935 of muscle, twitch strength and, 419 oxygen unloading and, 885, 885 pyrexia (See Fever) reaction rates and, 57 set point for, 826 water loss and, 933, 935 Temporal lines, 238, 243 Temporal lobe, 515, 530, 531 effect of lesions on, 538 primary auditory cortex in, 605, 606 surface anatomy, 513 Temporal region, 381 Temporal summation, 420, 421, 427, 467, 467, 468 Tendinitis, 306t Tendinous cords, 719, 719–720, 721, 722, 735 Tendinous intersections, 335–337, 335t Tendon organs, 505, 505, 586, 587t Tendon reflex, 505, 505–506 Tendons generally, 284 connective tissue of, 154, 154, 156 dense regular connective tissue in, 158, 158t in indirect muscle attachment, 317, 358, 366 specific biceps brachii, 299 calcaneal (Achilles), 270, 271, 305, 306, 317, 320, 366, 368, 368t, 397–399, 403, 426–427, 506 common flexor, 354 extensor digiti minimi, 395 extensor digitorum, 395 extensor digitorum longus, 398, 399 extensor hallucis longus, 398 extensor pollicis brevis, 395 extensor pollicis longus, 395 fibularis brevis, 306, 397 fibularis longus, 306, 397 flexor carpi radialis, 285, 317, 356, 358, 395 flexor carpi ulnaris, 356 flexor digitorum profundus, 285, 354, 356 flexor digitorum superficialis, 285, 354, 356 flexor pollicis longus, 285, 356 iliotibial band, 320, 361t, 363, 396, 397 infraspinatus, 299 intermediate, 328t palmaris longus, 317, 356, 358, 395 patellar retinacula, 301 quadriceps femoris, 268, 363, 363t, 364, 396 semimembranosus, 397 semitendinosus, 397 subscapularis, 299 supraspinatus, 299 teres minor, 299 tibialis anterior, 397 Tendon sheaths, 284, 285, 299 Tennis elbow/tennis leg, 374 Tenting effect, 1085, 1086 Tentorium cerebelli, 517 I-44 sal78259_index.indd I-44 11/19/10 1:43 PM Teratogens, 1120–1121, 1121 Teratology, 1120 Terminal authorization of axon, 443, 444 Terminal button, 443, 444 Terminal cisternae, 404, 404, 407t Terminal filum, 482 Terminal web, 83, 89, 102, 103 Termination, in translation, 124, 125 Terminologia Anatomica (TA), 20, 265 Tertiary structure of protein, 67, 68, 126 Tertiary syphilis, 1060 Testes, 1035, 1041, 1042, 1043, 1044 anatomy of, 385, 392 as cytogenic glands, 169, 651 descent of, 1040, 1040 endocrine functions of, 651, 652, 654t Testicles, 21 Testicular cancer, 1036, 1040, 1059t Testicular feminization, 660, 1036, 1036 Testis-determining factor, 1037 Testosterone, 649, 652, 656, 657 bone growth and metabolism, 224, 225t pattern baldness and, 192–193 prenatal, 1037 secretion of, 641, 1048, 1048 synthesis of, 128–129, 129 used as performance enhancer, 74 Tetanic stimulation, 471 Tetanus (lockjaw), 410 Tetanus of muscle, 419, 420–421, 421 Tetany, 221, 941 Tetrads, 1050, 1051 Tetrahydrocannabinol (THC), 1002 Tetraiodothyronine See Thyroxine Texture mouthfeel, 586, 587, 587t receptors for, 586, 587, 587t Thalamus, 483, 485, 515, 519, 523, 528, 529, 533 role in equilibrium, 609, 609 role in general senses, 541 role in taste, 593 in spinal gating, 590, 590 surgical treatment of parkinsonism, 473 Thalassemia, 690, 709t Thalidomide, 1121, 1121 Theca, 651, 651 Theca externa, 1079 Theca folliculi, 1078, 1079, 1079 Theca interna, 1079, 1082 Thelarche, 1075 Thenar eminence, 357t, 358, 394, 395 Theories, scientific, Thermal stability of water, 51–52 Thermoreceptors, 182, 585 Thermoregulation, 17, 17–18, 1025, 1027 aging and, 1125, 1127, 1129 alcohol and, 1028 disturbances of, 1027–1028 medical history, 18 neonatal adaptations, 1120 role of hypothalamus in, 528, 529 by skin, 182 Theta waves, 535, 535, 536, 536 Thiamine, 1011t, 1029 Thick filaments, 404–405, 405, 407t Thick skin, 182, 183 Thigh, 32, 34 rotation of, 361, 362t surface anatomy, 396 Thin filaments, 83, 102, 103, 109t, 405, 405, 407t Thin skin, 182, 186 Third-degree burns, 199, 200, 201 Third heart sounds, 736–737 Thirst, 909, 909, 933, 933–934 Thoracic cage, 233, 256, 257, 258–259 elastic recoil of, 870 ribs, 257–259, 258–259, 260t, 387, 390 role in breathing, 258, 867, 868, 872 sternum, 257, 258 Thoracic cavity, 34, 34–36, 35, 159 Thoracic curvature, 251, 251 Thoracic ducts, 810, 812–813, 814 Thoracic lymph nodes, 819 Thoracic pump, 769 Thoracic region, 31, 32, 479, 480 arteries of, 781, 781t–782t surface anatomy of, 388, 390 veins of, 783t, 784 Thoracic vertebrae, 255, 255–256 Thorax See Thoracic region Threonine, 122t, 125, 131 Threshold, 418, 455 Thrombin, 705, 706 Thrombocytes See Platelet(s) Thrombocytopenia, 703, 709t Thromboembolism, 708 Thrombokinase, 706, 707t Thromboplastin, 1006 Thrombopoiesis, 703 Thrombopoietin, 703 Thrombosis, 708–709 aging and, 1128 cerebral ischemia due to, 771 Thromboxanes, 666, 667, 704 Thrombus, 708 Thrush, 845 Thucydides, 830 Thumb (pollex), 263, 264, 394, 395 opposable thumbs, 11, 11, 290 special movements of, 295–297, 296 thenar eminence, 357t, 358 Thymectomy, 434 Thymic corpuscles, 816, 817 Thymine, 115, 116 Thymopoietin, 645, 653t, 816 Thymosin, 645, 653t, 816 Thymulin, 645, 653t, 816 Thymus, 645t, 646, 653t, 810 as lymphatic organ, 816, 817, 832, 832, 833 T cells (See T lymphocytes) Thyretin, 660 Thyroglobulin, 658, 658–659, 659 Thyroid cartilage, 159, 388, 859, 859 Thyroid follicles, 646, 647 Thyroid gland, 385, 646, 646–647, 647, 653t C cells of, 223 disorders of, 668–669, 669, 672t in pregnancy, 1088 Thyroid hormone, 637t, 642, 646 action on target cells, 661, 661 in bone metabolism, 225t calorigenic effects of, 661 chronotropic effects, 742, 743t negative feedback inhibition, 643–644, 644 in protein synthesis, 1021 total metabolic rate and, 1025 Thyroid-stimulating hormone (TSH), 637, 637t, 639, 641, 641t, 642, 644 hypersecretion of, 668–669, 669 negative feedback inhibition, 643–644, 644 in synthesis of thyroxine, 659, 659 Thyrotropin-releasing hormone, 637t, 639, 640t, 642, 643–644, 644 Thyroxine, 637t, 646, 653t, 656 secretion of, 661 synthesis of, 658, 658–659, 659 Thyroxine-binding globulin, 660 Tic douloureux, 556 Tidal volume, 875, 876 Tight junctions, 184 See also Gap junctions in blood-CSF barrier, 521 histology, 166, 166 in spermatogenesis, 1052, 1053 of stomach, 972 tubular reabsorption and, 910, 911 Timekeeping center, 527 Tinea, 198t Tip link, 602, 603 Tissandier, Gaston, 878 Tissue(s), 13, 13, 144–146 See also specific tissue types degeneration and death of, 173, 175 growth and development of, 172 interpreting tissue sections, 145, 145–146, 146, 157 primary classes of, 144–145, 144t role of stem cells, 172 tissue repair, 172–173, 174 Tissue engineering, 175, 175, 201 Tissue fluid, 82, 144–145, 931 Tissue plasminogen activator, 710 Tissue thromboplastin, 705, 706, 707t Titin, 405, 407t T lymphocytes (T cells), 695, 808, 813, 823 activation of, 835, 836 life history of, 832, 832–833 maturation in thymus, 645 in specific immunity, 832, 832–833, 842t T cell recall response, 835 Toes anatomy of, 32, 34 hallux (great toe), 270–271, 271, 273, 273, 398 Tongue, 382, 858 anatomy of, 958, 958–959, 959 extrinsic muscles of, 327, 327t intrinsic muscles of, 327t, 959, 959 Tonic contraction, 432 Tonicity, 94, 94–95 Tonic receptors, 585 Tonic response, 502 Tonsil(s), 820, 820 Tonsillar crypts, 820, 820 Tonsillectomy, 820 Tonsillitis, 820 Total body water, 931 Total dead space, 874 Total heart block, 729 Total hip replacement, 307, 308 Total lung capacity, 875, 876 Total metabolic rate, 1025 Total parenteral nutrition, 949 Total WBC count, 681t Totipotent stem cells, 172 Touch receptors, 586, 587, 587t Toxic goiter, 668, 672t, 843 Toxic hypervitaminosis, 1012 Toxins, 1022t, 1088–1089 Toxoplasma infection, 845, 1121 Trabeculae carneae, 719, 719, 721 of exocrine gland, 168, 168 in intramembranous ossification, 214, 215 of penis, 1047 of spongy bone, 212, 213 Trace elements, 43 Trace minerals, 1010t Trachea, 382, 386, 856, 858 anatomy of, 860–862, 860–862 cartilage of, 159, 860–861, 861 mucosa of, 150, 150t, 171 Tracheostomy, 861 Traction, 227 Tracts See also specifically named tracts of cerebral white matter, 514, 515, 518, 519, 531, 532 I-45 sal78259_index.indd I-45 11/19/10 1:43 PM digestive tract, 954–956, 955, 956, 957 of spinal cord (See Spinal tracts) Transamination, 1021 Transcellular fluid, 931 Transcellular route, 910, 911, 989 Transcortin, 660 Transcription, 122, 123, 126, 128, 128 Transcription activator, 128, 128 Transcytosis, 99–100, 100, 766, 766 Transdermal absorption, 182 Transducers, 583 Transduction, 583 Trans-fatty acids, 64, 64 Transferrin, 682t, 687, 687, 688, 989 Transferrin-iron complex, 989 Transfer RNA (tRNA), 119, 122–123, 123 Transfusion compatibility, 87–88 Transfusion reaction, 692–693, 694, 843 Transient ischemic attacks (TIAs), 771 Transitional period, neonatal, 1119 Translation, 122–123, 123–126, 125–126 Transmembrane proteins, 85, 85 Transmission electron microscope (TEM), 81, 81, 82, 82t Transport, 679 Transport maximum, 95, 95, 670, 912, 912 Transport proteins, 660, 660, 910, 911 Transport vesicles, 124, 125, 126, 127 trans-Retinal, 620, 621, 622, 622 Transudation, 1070 Transverse arch of foot, 272, 272, 398 Transverse colon, 391 Transverse plane, 30, 30, 288, 289 Transverse rectal folds, 990, 991 Transverse section, 146, 146 Transverse (T) tubules, 404, 404, 407t, 412, 414 Traumatic injury ankle sprains, 305 to anterior cruciate ligament, 305, 305 to back, 340 to brain, 539, 539, 556t to ethmoid bone, 246 to kidney, 905 knee injuries, 302, 305, 305 to muscles, 374 nephron destruction due to, 925 nerve injuries, 497 regeneration of nerve fibers, 450–451, 451 repetitive motion injury, 352t, 356, 356 resistance of skin to, 181 to spinal cord, 507 to spleen, 821 Treatment group, T-regs, 834 Trephination, 628 Treponema pallidum bacteria, 1060 Treppe, 419, 420, 421 Triacylglycerols, 63 Triad, in muscle fiber, 404, 404 Triangles anal, 341t, 342 femoral, 801, 801 urogenital, 341t, 342 Triangular muscle shape, 315, 315 Trichromatic (color) vision, 11, 620, 620, 623–624, 625 Tricuspid valve, 719, 722, 722 Trigeminal neuralgia, 556 Trigger zone, 443, 450, 455, 457 Triglycerides, 156, 159, 987, 988 Trigone, 921, 922 Triiodothyronine, 637t, 646, 659, 659 Trimesters, 1087, 1106, 1106t Tripeptides, 67 Triple rhythm (gallop), 737 Triplo-X syndrome, 1122, 1122 Trisomy, 1122 Trisomy-21, 473 Trisomy-21 (Down syndrome), 473, 572, 1123, 1124 Tristearin, 62 Tritium, 45, 45 Trochanters, 213, 219–220, 236t, 237, 267, 269, 389 Trochlea, 261, 262, 611–612, 612 Trochlear notch, 262, 262–263 Trochlear surface of calcaneus, 270, 271 Trophoblast, 1106, 1108 Trophoblastic nutrition, 1111, 1113 Tropomyosin, 405, 405, 407t, 412, 414, 416, 417 Troponin, 405, 407t, 412, 414 Trousseau sign, 221 Trunk (region), 31, 32 muscles of, 333–343 anterior abdominal wall, 335–337, 335t–337t back muscles, 338–340, 338t–340t muscles of pelvic floor, 341t–342t, 342 muscles of respiration, 333t–334t, 334 special movements of, 294, 295 surface anatomy, 383–393 Trunks of spinal nerves, 496, 496t Trypsin, 69, 71, 979, 979, 985, 986 Trypsinogen, 979, 979, 979t Tubal ligation, 1097 Tubal pregnancy, 1108 Tubercles of bone, 236t, 237 cervical vertebrae, 253, 254 conoid tubercle, 260, 260 humerus, 261, 262 pelvis, 33, 33–34 ribs, 258, 258, 259 genital, 1037, 1039 Tuberculosis, 252, 888t Tuberculosis skin test, 844 Tuberculum sellae, 244 Tuberosity of bone, 236t, 237 deltoid, 261, 262 gluteal, 267, 269 ischial, 266, 267 radial, 262, 262 tibial, 269, 270, 303, 396 Tubular exocrine gland, 169, 169 Tubular fluid, 904 Tubular reabsorption, 905, 910–914 DCT and collecting duct, 913–914 nephron loop, 913 proximal convoluted tubule, 910–913 Tubular secretion, 905, 913, 943, 944 Tubulin, 102, 104 Tubuloacinar glands, 169, 169, 962, 962, 963 Tubuloglomerular feedback, 907–908, 908 Tufted cells, 594, 595 Tumor(s) of adrenal medulla, 668, 672t brain tumors, 447 development of (neoplasia), 172 estrogen-dependent, 660 of parathyroid, 669 of pineal gland, 645 tumor angiogenesis, 138, 139, 762 Wilms tumor, 139 Tumor necrosis factor (TNF), 835, 842t Tumor-suppressor genes, 138–139 Tunica albuginea, 1042, 1043 of ovaries, 1065, 1067 of penis, 1046, 1047, 1057 externa, 751, 751, 752, 812 fibrosa, 613, 613 interna of blood vessels, 170, 171, 750–751, 751, 752 of eye, 613, 613 of lymphatic system, 812, 812 media of blood vessels, 751, 751, 752, 753 of lymphatic system, 812 vaginalis, 1040, 1040 vasculosa, 613, 613 Turbinates, 857, 858 Turner syndrome, 1122, 1122–1123, 1123 T wave, 731, 732–733 Twins, 671, 1107, 1107, 1130 Two-point touch discrimination, 584, 584 Tympanic cavity, 597, 598 Tympanic membranes, 597, 598, 599, 599, 601, 602, 602 Tympanic part of temporal bone, 243, 243 Tympanic reflex, 601 Tyrosine, 136–137 U Ulcerative colitis, 994t Ulnar flexion, 295–297, 296 Ulnar notch, 262, 262 Ultrasonic frequencies, 596, 596 Ultrastructure, Ultrastructure of cell, 81, 81 Ultraviolet (UV) radiation, 610 photoaging and, 1125, 1126 production of vitamin D, 188, 222, 222 resistance of skin to, 181 skin color and, 187, 188 sunscreens and, 198 Umami, 592 Umbilical cord, 1087, 1112, 1113, 1113, 1115, 1116, 1117 cutting, 1091, 1092 development of, 1111 Umbilical hernia, 343 Umbilical-placental circuit, 1114, 1115 Umbilical region, 32, 33, 34 Umbilicus, 383, 388 Unbound hormones, 660, 660 Uncompensated acidosis/alkalosis, 947 Unencapsulated nerve endings, 586, 586, 587t Unicellular glands, 150, 168 Unipennate muscle shape, 315, 315 Unipolar neurons, 444, 445 Uniport, 95, 97, 101t Unipotent stem cells, 172 Unit membrane, 83 Universal donor, 692 Universal recipient, 692 Unmyelinated nerve fibers, 450, 450, 457–458, 458 Upper limb, 32, 34 adaptation for bipedalism, 274 antebrachium (See Forearm) arm proper, 261 arteries of, 792t–794t, 793 bones of, 261–263 embyronic limb rotation, 271, 271 muscles acting on, 336, 343, 346t–349t, 346t–358t, 347, 348 surface anatomy, 393–395, 394 veins of, 794t, 795 I-46 sal78259_index.indd I-46 11/19/10 1:43 PM Upper motor neurons, 486, 487, 543 Upper respiratory tract, 856, 856 Up-regulation of target cells, 664, 664 Uracil, 116, 119 Urea, 95, 681, 1021 Urea cycle, 1021 Uremia, 898 Ureters, 14, 386, 896, 897, 921, 922 Urethra, 387, 392, 896, 897, 1066 external orifice, 921, 922 membranous, 921–922, 922, 1045, 1045 penile, 922, 922, 1045, 1045 prostatic, 921, 922, 1045, 1045 Urethral glands, 922, 922 Uric acid, 898 Urinalysis, 918 Urinary bladder, 384, 386, 392, 896, 897, 1066 bladder control, 924t, 1089, 1129 disorders of, 921, 924 rugae of, 921, 922 stretched, 432 Urinary incontinence, 924t, 1089, 1129 Urinary pole of renal corpuscle, 901, 902 Urinary system, 37, 38, 895–926 adjustments to pregnancy, 1089 disorders of, 921, 924t functions of, 896–898 interactions with other systems, 926 senescence, 1128–1129 Urinary tract infection, 918, 921 Urine, 904 acid buffering in, 944, 945 composition and properties of, 918–919, 919t formation of glomerular filtration, 904–909, 905 tubular reabsorption and secretion, 905, 910–914 water conservation, 914–916 regulation of output, 934, 934 storage and elimination, 920–924 voiding, 922–924, 923 volume, 919 water loss in, 932, 932 Urobilinogen, 689, 977 Urochrome, 689, 918 Urogenital folds, 1037, 1039 Urogenital system, 37 Uronic acid, 155 Urticaria, 848t Uterine contractions, 1087–1088 Uterine milk, 1111 Uterine tubes, 386, 1066, 1066–1067, 1068, 1069, 1081 Uterus, 386, 392, 1066, 1067, 1068, 1069, 1085 blood supply, 1069, 1071, 1084 contractility of, 1087, 1090–1091 growth during pregnancy, 1089, 1090, 1909t involution of, 1093 ligaments, 1066, 1068, 1069 as potential space, 37 sperm migration to, 1103 wall of, 1069, 1071 Utilization coefficient, 884 Utricle, 599, 605–607, 607 Uvea, 613, 613 Uvula, 858, 959 V Vaccination, 831 Vaccine, 831 Vagal tone, 741 Vagal trunks, 571 Vagina, 1070–1071 anatomy of, 387, 392 fornices of, 1066, 1068, 1070 rugae, 1066, 1070–1071, 1085 vestibular bulbs, 1072, 1072 Vaginal mucosa, 151, 151t, 153 Vaginal orifice, 1066 Vaginal process, 1040, 1040 Vaginal transudate, 1085 Vagovagal reflexes, 957 Vagusstoffe (“vagus substance”), 461 Valence (charge), 47 Valence electrons, 44, 45, 46–47 Vallate papillae, 591, 592, 959, 959 Valsalva maneuver, 855, 868, 924, 993, 1091 Valves See also specific valves of heart (See Heart valves) lymphatic, 812, 812 venous, 757, 770 Valvular insufficiency, 735 Valvular stenosis, 735 Van der Waals forces, 48t, 49–50, 67 Variable region, 838 Varicocele, 1059t Varicose veins, 757, 1128 Varicosities, 429, 429, 443, 444, 564, 564 Vasa recta, 900, 900, 901, 916, 917 Vasa vasorum, 751, 752 Vascular plexuses choroid, 515, 518, 519, 521 pampiniform, 1041, 1042, 1042, 1044 Vascular pole of renal corpuscle, 901, 902 Vascular (venous pooling) shock, 770 Vascular spasm, 704, 704 Vas deferens, 1043, 1044–1045, 1045 Vasectomy, 1044, 1097, 1132 Vasoactive chemicals, 762, 829 Vasoactive intestinal peptide, 970 Vasocongestion, 1055, 1056, 1085 Vasoconstriction, 17, 18, 576, 576 blood pressure and, 764 calcium channel blockers used for, 86 in regulation of GFR, 909, 909 resistance to flow and, 760, 761 respiratory system and, 855 in thermoregulation, 1027 in ventilation-perfusion coupling, 880, 882 Vasoconstrictors, 703, 704 Vasodilation, 17, 17–18, 576, 576, 760, 880, 882 Vasodilators, 697 Vasomotion purposes of, 763–764, 764, 765 tunica media and, 751 vasoactive chemicals and, 762 Vasomotor center, 522, 762, 763 Vasomotor tone, 432, 576, 576, 770 Veins generally anatomy of, 751, 756, 756–757, 770 disorders of, 757 great vessels, 715–716 histology, 751, 756 sizes of, 751, 756–757, 770 venous return (See Venous return) specific arcuate, 900, 900 axillary, 385, 775, 780, 794t, 795 azygos, 783t, 784 basilic, 775, 794t, 795 brachial, 385, 773, 775, 794t, 795 brachiocephalic, 385, 775, 780, 783t, 784, 795 bronchial, 782t cardiac, 724, 725 central, 974, 976, 977 central longitudinal, 816 cephalic, 383, 385, 775, 794t, 795 cerebral great, 780 superficial middle, 779t, 780 cortical radiate, 900, 900, 901 cystic, 790t, 791 deep dorsal, 1055 esophageal, 782t facial, 779t, 780 femoral, 383, 384, 773, 775, 792, 798, 799, 799t fibular, 775, 798, 799, 799t gastric, 790t, 791 gastro-omental, 791 gonadal, 775, 789, 789t hemiazygos, 783t, 784 hemorrhoidal, 990, 991 hepatic, 386, 775, 789, 789t, 790t, 791, 977 hepatic portal, 790t, 791, 975, 976, 977 iliac common, 775, 784, 789, 789t, 798, 799, 799t external, 775, 789, 789t, 798, 799, 799t internal, 775, 789, 789t iliolumbar, 784, 789 intercostal posterior, 783t, 784 superior, 784 interlobar, 900, 900 interlobular, 900, 900, 901 jugular, 795 external, 384, 775, 779t, 780 internal, 384, 390, 775, 779t, 780 left marginal, 724, 725 lumbar, 789, 789t ascending, 783t, 784, 789, 789t, 790t left or right, 784 median antebrachial, 775, 794t, 795 median cubital, 394, 794t, 795 mediastinal, 782t mesenteric inferior, 790t, 791 superior, 386, 391, 790t, 791 occipital, 780 ophthalmic, 779t, 780 ovarian, 789, 789t, 1067, 1068 palmar arches deep, 794t, 795 superficial, 794t, 795 palmar venous network, 794t, 795 pancreatic, 790t, 791 pericardial, 782t phrenic, 789, 789t plantar lateral, 798, 799, 799t medial, 798, 799, 799t plantar venous arch, 775, 798, 799, 799t popliteal, 775, 798, 799, 799t pulmonary, 720, 721, 723, 772, 773 radial, 775, 792, 794t, 795 renal, 773, 775, 784, 789, 789t, 899, 899, 900, 900 sacral, 789 saphenous great, 383, 775, 798, 798t, 799 small, 775, 798, 798t, 799 splenic, 790t, 791 I-47 sal78259_index.indd I-47 11/19/10 1:43 PM subclavian, 258, 385, 390, 775, 780, 783t, 784, 794t, 795 subcostal, 783t, 784 suprarenal, 789, 789t temporal, 779t, 780 testicular, 1043, 1044 thesbian, 725 thyroid, 779t, 780 tibial anterior, 775, 798, 799, 799t posterior, 775, 798, 799, 799t ulnar, 773, 775, 794t, 795 umbilical, 1112, 1114, 1115 vena cava inferior, 386, 391, 715, 720, 721, 722, 769, 775, 784, 789, 789t, 791, 977, 1114, 1115 superior, 385, 386, 715, 720, 721, 722, 775, 783t, 784, 795 venous arches dorsal, 775, 798, 798t, 799 palmar, 775 venous network, dorsal, 775, 794t, 795 vertebral, 254, 779t, 780 Venous anastomoses, 757, 758, 792 Venous pooling, 770 Venous pooling (vascular) shock, 770 Venous reserve, 884 Venous return, 742, 769, 769–770 aging and, 1128 circulatory shock and, 770 mechanisms of, 769 in pregnancy, 1089 role in edema, 768 Venous valves, 757, 770 Ventilation-perfusion coupling, 879–881, 882 Ventral (position), 31, 31t, 1046, 1047 Ventral respiratory group, 869, 869–870 Ventricles of brain, 518, 519 fourth, 515, 518, 519 lateral, 515, 518, 519 third, 518, 519 cardiac, 390, 718–719, 719–721, 723 Ventricular ejection, 730, 737, 738 Ventricular fibrillation, 729, 733 Ventricular filling, 737, 738, 739 Ventricular hypertrophy, 733t, 743–744 Ventricular myocardium, 742 Venules muscular, 756–757 postcapillary, 756 Vermilion of lips, 958 Vermis, 526, 527 Vernix caseosa, 1118t Vertebrae, 250, 253–256, 390, 392 atlas (C1), 253, 254 axis (C2), 253–254, 254 cervical, 253–255, 254, 255 coccygeal, 256, 257 lumbar, 255, 256, 387 sacral, 256, 257, 266 structure of, 251–253, 253, 254 superficial anatomy, 391 thoracic, 255, 255–256 vertebra prominens (C7), 255 Vertebral column, 250–256, 382 adaptation for bipedalism, 274, 274 curvatures (See Spinal curvatures) general features of, 250–251, 251, 252 intervertebral discs (See Intervertebral discs) Vertebral notches, 253, 254 Vertebral region, 32 Vertex position, 1090, 1090, 1118t Very low-density lipoproteins (VLDLs), 1007, 1008 Vesalius, Andreas, 4–5, 5, 715 Vesicles, 98, 100 Vesicouterine pouch, 1066, 1069 Vesicular transport, 98–100, 98–100, 101t Vestibular apparatus, 599, 605 Vestibular bulbs, 1072, 1072 Vestibular folds, 857, 858, 859, 859, 860 Vestibular membrane, 599–600, 600 Vestibule, 598, 599, 857, 858, 958, 1071, 1072 Vestibulo-ocular reflex, 609 Vestibulospinal tracts, 484t, 485, 486–487, 544 Vestigial organs, 10 Viagra, 1057 Vibrissae, 194, 857, 858 Victoria, Queen of England, 708 Villi chorionic, 1108, 1111, 1112, 1113, 1114 of intestinal wall, 981, 982 microvilli, 83, 88, 88–90, 89, 109t Villous chorion, 1111 Viral envelope, 845 Viruses See also specific viruses as cause of Bell palsy, 556 meningitis caused by, 518 role in diabetes mellitus, 670 Viscera, 34 Visceral effectors, 562 Visceral motor division of PNS See Autonomic nervous system Visceral muscle, 164, 165, 165t, 429–430, 430, 431 Visceral pain, 588–589, 589 Visceral pericardium, 35, 35, 716, 717, 718–721 Visceral peritoneum, 36, 36, 37 Visceral pleura, 35, 35–36, 864, 866 Visceral reflexes, 441, 501, 562–563, 563 Visceral sensory division of PNS, 441, 441 Viscosity of blood, 681, 681t, 682–683, 690, 760 Vision, 540, 541, 610–627 accessory structures of orbit, 610–612, 610–612 anatomy of eye, 612–615, 613 color vision, 623–624, 625 depth perception, 11 disorders of blindness, 670, 671 cataracts, 614, 1127 detached retina, 615 glaucoma, 614, 1127 Kearns-Sayre syndrome, 110 Leber hereditary optic neuropathy, 110 presbyopia, 1127 ptosis, 434, 434 strabismus, 434 dual vision system, 623, 624 duplicity theory of, 623, 624 image formation, 615–617 light and, 610 light and dark adaptation, 623 sensory transduction in retina, 617, 619, 619–623, 620 stereoscopic, 624–625, 625 visual projection pathway, 625–627, 626 Visual association area, 540, 541, 627 Visual center, 530 Visual filling, 615, 615 Visual pigments, 620, 621 Visual purple (rhodopsin), 619, 620, 621 Vital capacity, 875, 876, 876 Vital signs, 1119 Vitamin(s), 1004t, 1011–1012, 1011t B complex, 987, 1011t deficiencies of, 1011–1012 digestion and absorption of, 987 fat-soluble, 62t, 988, 1006 metabolism of, 1022, 1022t Vitamin A (retinol) in bone metabolism, 225t deficiency or excess of, 1011–1012 digestion and absorption of, 987 fat-soluble, 1006 sources and requirements, 1011t Vitamin B12 (cobalamin) deficiency of, 689–690, 689t digestion and absorption of, 987 sources and requirements, 1011t Vitamin C (ascorbic acid), 48 in bone metabolism, 225t digestion and absorption of, 987 sources and requirements, 1011t Vitamin D (calcitriol), 652, 654t, 655, 655t, 914, 917t in bone metabolism, 225t in calcium homeostasis, 222, 222–223 digestion and absorption of, 987 in electrolyte balance, 941 fat-soluble, 1006 in mineral absorption, 989 needs in pregnancy, 1089 in old age, 1125–1126 in phosphate homeostasis, 224 sources and requirements, 1011t synthesized by skin, 181, 188 ultraviolet rays and, 188, 222, 222 Vitamin E (alpha-tocopherol), 48 digestion and absorption of, 987 fat-soluble, 1006 sources and requirements, 1011t Vitamin K (phylloquinone) in coagulation, 710 digestion and absorption of, 987 fat-soluble, 1006 injections, 1120 needs in pregnancy, 1089 sources and requirements, 1011t synthesis of, 992 Vitamin K antagonists, 710 Vitelline duct, 1110 Vitreous body, 155, 613, 614, 614–615, 619 Vitreous chamber, 614 Vocal cords, 156, 382, 858, 859, 859, 860 Voiding, 1129 Volar surface of fingers, 394 Volta, Alessandro, 419 Voltage-gated ion channels, 86 in electrical behavior of myocardium, 730, 730 in excitation, 412, 413, 414 in signal conduction, 457–458, 459 of smooth muscle, 431 Volume See Blood volume Voluntary control of breathing, 871 Voluntary muscle, 164, 402–403 Vomiting, 970–972 Vulva, 1071, 1072 I-48 sal78259_index.indd I-48 11/19/10 1:43 PM W Warfarin, 710 Warm receptors, 586 Wastes, 897, 913 Water, 50–52, 51 capillary fluid exchange, 766–768 conservation of (See Water conservation) daily requirements, 1004, 1004t in plasma, 682t, 684 tubular reabsorption of, 911, 911 Water balance, 931–936, 989 aging and, 1128–1129 disorders of, 934–936 fluid compartments, 931, 932 intake regulation, 933, 933–934 neonatal adaptations, 1120 output regulation, 934, 934 water gain and loss, 931–933, 932 Water conservation, 914–916 collecting duct, 914, 915 control of water loss, 914–915 countercurrent exchange system, 916, 917t, 918 countercurrent multiplier, 915–916, 916, 917 Water diuresis, 914–915 Water-insoluble fiber, 1006 Water intoxication, 936, 936t Water output, 897 Water-soluble fiber, 1006 Water-soluble vitamins, 1011, 1011t Watson, James, 117, 117 Wave summation, 420, 421 Weak acid, 942 Weak base, 942 Weight See Body weight Weight-control drugs, 1002 Weight per volume of solution, 53 Wells, Horace, 628 Werner syndrome, 1130 Wernicke aphasia, 545 Wernicke area, 543, 545, 545, 557, 557 “Wet dreams,” 1049 White blood cells See Leukocytes White fat, 156, 159 White fibers, 154, 154 White matter of brain, 514, 518, 519, 526, 527 of cerebrum, 515, 531, 532, 626, 626 of spinal cord, 481, 482, 483 White muscle fibers, 426, 426–427, 426t, 427t White pulp of spleen, 821, 821 “Widow’s hump,” 228, 228, 252, 252 Wilkins, Maurice, 117 Wilms tumor, 139 Wisdom teeth, 961, 961 Withdrawal (coitus interruptus), 1096 Withdrawal reflex, 471, 504, 504–505 Wolffian duct, 1037, 1038 Wolff’s law of bone, 213, 219, 220 Women See Female(s) Work, 56 Working memory, 471 Wormian (sutural) bones, 234, 240 Wrinkling, 1125, 1126 Wrist, 32, 34, 261 muscles acting on, 352t–355t, 353, 354, 356 surface anatomy, 395 Wrist drop, 497 X X chromosomes, 134, 1122–1123, 1122–1124 Xenograft, 201 X-linked traits, 137, 137 X-ray diffraction, 117 X-rays, 23, 23–24, 1120, 1121 Y Y chromosome, 134, 1037 Yellow bone marrow, 213, 214, 815 Yellow fibers, 155 Yolk sac, 683, 1108, 1108–1110, 1109, 1111, 1112 Z Z disc, 405, 406, 407, 407t Zeiss, Carl, Zero position, 291, 297, 297 Zinc, 1010t Z line, 407 Zodiac, 4, Zona drilling, 1132 Zona fasciculata, 648, 649 Zona glomerulosa, 648, 649 Zona pellucida, 1078, 1079, 1079, 1104, 1105, 1106 Zona reticularis, 648, 649 Zone of bone deposition, 217, 218 Zone of calcification, 217, 218 Zone of cell hypertrophy, 217, 218 Zone of cell proliferation, 217, 218 Zone of reserve cartilage, 217, 218, 218 Zygomatic branch of facial nerve, 552, 552t Zygote, 1035, 1105, 1105 Zygote intrafallopian transfer (ZIFT), 1133 Zymogen granules, 978, 978 Zymogens, 969 I-49 sal78259_index.indd I-49 11/19/10 1:43 PM ... forearm and wrist; joints of elbow, wrist, and hand Median n Mixed Lateral and medial Skin of lateral two-thirds of hand; tips of digits I–IV; joints of hand Ulnar n Mixed Medial Skin of palmar and. .. and superficial) Pudendal n Mixed Skin of anterior distal third of leg, dorsum of foot, and toes I–II; knee joint Mixed Skin of penis and scrotum of male; clitoris, labia majora and minora, and. .. sal7 825 9_ch 12_ 439-477.indd 4 72 11/15/10 8:59 AM CHAPTER 12 an important center of memory Nerve cells exhibit neurofibrillary tangles—dense masses of broken and twisted cytoskeleton (fig.  12. 31)