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Chapter 12 - The central nervous system (part c), in this chapter you will learn about the following: Functional brain systems, limbic system, limbic system: emotion and cognition, reticular formation, reticular formation: RAS and motor function, electroencephalogram (EEG), brain waves,...and other contents.
PowerPoint® Lecture Slides prepared by Vince Austin, Bluegrass Technical and Community College CHAPTER 12 The Central Nervous System: Part C Copyright © 2010 Pearson Education, Inc Functional Brain Systems • Networks of neurons that work together and span wide areas of the brain • Limbic system • Reticular formation Copyright â 2010 Pearson Education, Inc Limbic System ã Structures on the medial aspects of cerebral hemispheres and diencephalon • Includes parts of the diencephalon and some cerebral structures that encircle the brain stem Copyright © 2010 Pearson Education, Inc Septum pellucidum Diencephalic structures of the limbic system •Anterior thalamic nuclei (flanking 3rd ventricle) •Hypothalamus •Mammillary body Olfactory bulb Copyright © 2010 Pearson Education, Inc Corpus callosum Fiber tracts connecting limbic system structures •Fornix •Anterior commissure Cerebral structures of the limbic system •Cingulate gyrus •Septal nuclei •Amygdala •Hippocampus •Dentate gyrus •Parahippocampal gyrus Figure 12.18 Limbic System • Emotional or affective brain • Amygdala—recognizes angry or fearful facial expressions, assesses danger, and elicits the fear response • Cingulate gyrus—plays a role in expressing emotions via gestures, and resolves mental conflict • Puts emotional responses to odors • Example: skunks smell bad Copyright © 2010 Pearson Education, Inc Limbic System: Emotion and Cognition • The limbic system interacts with the prefrontal lobes, therefore: • We can react emotionally to things we consciously understand to be happening • We are consciously aware of emotional richness in our lives • Hippocampus and amygdala—play a role in memory Copyright © 2010 Pearson Education, Inc Reticular Formation • Three broad columns along the length of the brain stem • Raphe nuclei • Medial (large cell) group of nuclei • Lateral (small cell) group of nuclei • Has far-flung axonal connections with hypothalamus, thalamus, cerebral cortex, cerebellum, and spinal cord Copyright © 2010 Pearson Education, Inc Reticular Formation: RAS and Motor Function • RAS (reticular activating system) • Sends impulses to the cerebral cortex to keep it conscious and alert • Filters out repetitive and weak stimuli (~99% of all stimuli!) • Severe injury results in permanent unconsciousness (coma) Copyright © 2010 Pearson Education, Inc Reticular Formation: RAS and Motor Function • Motor function • Helps control coarse limb movements • Reticular autonomic centers regulate visceral motor functions • Vasomotor • Cardiac ã Respiratory centers Copyright â 2010 Pearson Education, Inc Radiations to cerebral cortex Visual impulses Reticular formation Ascending general sensory tracts (touch, pain, temperature) Copyright © 2010 Pearson Education, Inc Auditory impulses Descending motor projections to spinal cord Figure 12.19 Arachnoid Mater • Middle layer with weblike extensions • Separated from the dura mater by the subdural space • Subarachnoid space contains CSF and blood vessels • Arachnoid villi protrude into the superior sagittal sinus and permit CSF reabsorption Copyright © 2010 Pearson Education, Inc Superior sagittal sinus Subdural space Subarachnoid space Copyright © 2010 Pearson Education, Inc Skin of scalp Periosteum Bone of skull Periosteal Dura Meningeal mater Arachnoid mater Pia mater Arachnoid villus Blood vessel Falx cerebri (in longitudinal fissure only) Figure 12.24 Pia Mater • Layer of delicate vascularized connective tissue that clings tightly to the brain Copyright © 2010 Pearson Education, Inc Cerebrospinal Fluid (CSF) • Composition • Watery solution • Less protein and different ion concentrations than plasma • Constant volume Copyright © 2010 Pearson Education, Inc Cerebrospinal Fluid (CSF) • Functions • Gives buoyancy to the CNS organs • Protects the CNS from blows and other trauma • Nourishes the brain and carries chemical signals Copyright © 2010 Pearson Education, Inc Superior sagittal sinus Choroid plexus Arachnoid villus Interventricular foramen Subarachnoid space Arachnoid mater Meningeal dura mater Periosteal dura mater Right lateral ventricle (deep to cut) Choroid plexus of fourth ventricle Third ventricle CSF is produced by the Cerebral aqueduct Lateral aperture Fourth ventricle Median aperture Central canal of spinal cord (a) CSF circulation Copyright © 2010 Pearson Education, Inc choroid plexus of each ventricle CSF flows through the ventricles and into the subarachnoid space via the median and lateral apertures Some CSF flows through the central canal of the spinal cord CSF flows through the subarachnoid space CSF is absorbed into the dural venous sinuses via the arachnoid villi Figure 12.26a Choroid Plexuses • Produce CSF at a constant rate • Hang from the roof of each ventricle • Clusters of capillaries enclosed by pia mater and a layer of ependymal cells • Ependymal cells use ion pumps to control the composition of the CSF and help cleanse CSF by removing wastes Copyright © 2010 Pearson Education, Inc Ependymal cells Capillary Section of choroid plexus Connective tissue of pia mater Wastes and unnecessary solutes absorbed CSF forms as a filtrate containing glucose, oxygen, vitamins, and ions (Na+, Cl–, Mg2+, etc.) (b) CSF formation by choroid plexuses Copyright © 2010 Pearson Education, Inc Cavity of ventricle Figure 12.26b Blood-Brain Barrier • Helps maintain a stable environment for the brain • Separates neurons from some bloodborne substances Copyright © 2010 Pearson Education, Inc Blood-Brain Barrier • Composition • Continuous endothelium of capillary walls • Basal lamina • Feet of astrocytes • Provide signal to endothelium for the formation of tight junctions Copyright © 2010 Pearson Education, Inc Capillary Neuron Astrocyte (a) Astrocytes are the most abundant CNS neuroglia Copyright © 2010 Pearson Education, Inc Figure 11.3a Blood-Brain Barrier: Functions • Selective barrier • Allows nutrients to move by facilitated diffusion • Allows any fat-soluble substances to pass, including alcohol, nicotine, and anesthetics • Absent in some areas, e.g., vomiting center and the hypothalamus, where it is necessary to monitor the chemical composition of the blood Copyright © 2010 Pearson Education, Inc Homeostatic Imbalances of the Brain • Traumatic brain injuries • Concussion—temporary alteration in function • Contusion—permanent damage • Subdural or subarachnoid hemorrhage—may force brain stem through the foramen magnum, resulting in death • Cerebral edema—swelling of the brain associated with traumatic head injury Copyright © 2010 Pearson Education, Inc Homeostatic Imbalances of the Brain • Cerebrovascular accidents (CVAs)(strokes) • Blood circulation is blocked and brain tissue dies, e.g., blockage of a cerebral artery by a blood clot • Typically leads to hemiplegia, or sensory and speed deficits • Transient ischemic attacks (TIAs)—temporary episodes of reversible cerebral ischemia • Tissue plasminogen activator (TPA) is the only approved treatment for stroke Copyright © 2010 Pearson Education, Inc Homeostatic Imbalances of the Brain • Degenerative brain disorders • Alzheimer’s disease (AD): a progressive degenerative disease of the brain that results in dementia • Parkinson’s disease: degeneration of the dopaminereleasing neurons of the substantia nigra • Huntington’s disease: a fatal hereditary disorder caused by accumulation of the protein huntingtin that leads to degeneration of the basal nuclei and cerebral cortex Copyright © 2010 Pearson Education, Inc ...Functional Brain Systems • Networks of neurons that work together and span wide areas of the brain • Limbic system • Reticular formation Copyright © 2010 Pearson Education, Inc Limbic System • Structures... of the Brain • Change with age, sensory stimuli, brain disease, and the chemical state of the body • EEGs used to diagnose and localize brain lesions, tumors, infarcts, infections, abscesses, and. .. gestures, and resolves mental conflict • Puts emotional responses to odors • Example: skunks smell bad Copyright © 2010 Pearson Education, Inc Limbic System: Emotion and Cognition • The limbic system