Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Human Anatomy & Physiology SEVENTH EDITION Elaine N. Marieb Katja Hoehn PowerPoint ® Lecture Slides prepared by Vince Austin, Bluegrass Technical and Community College C H A P T E R 12 The Central Nervous System P A R T C

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Brain Waves  Normal brain function involves continuous electrical activity  An electroencephalogram (EEG) records this activity  Measures electrical potential differences between various cortical areas  Patterns of neuronal electrical activity recorded are called brain waves  Each person’s brain waves are unique

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Types of Brain Waves Figure 12.20b

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Brain Waves: State 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 epileptic lesions  A flat EEG (no electrical activity) is clinical evidence of death

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Epilepsy  A victim of epilepsy may lose consciousness, fall stiffly, and have uncontrollable jerking, characteristic of epileptic seizure  Caused by uncontrolled flood of electrical discharges of groups of neurons in the brain during which time no other messages can get through  Epilepsy is not associated with, nor does it cause, intellectual impairments  Epilepsy occurs in 1% of the population

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Epileptic Seizures  Absence seizures, or petit mal – mild seizures seen in young children where the expression goes blank  Tonic-clonic or Grand mal seizures – victim loses consciousness, bones are often broken due to intense convulsions, loss of bowel and bladder control, and severe biting of the tongue

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Control of Epilepsy  Epilepsy can usually be controlled with anticonvulsive drugs  Vagus nerve stimulators can be implanted under the skin of the chest and can keep electrical activity of the brain from becoming chaotic

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Consciousness  Encompasses perception of sensation, voluntary initiation and control of movement, and capabilities associated with higher mental processing  Involves simultaneous activity of large areas of the cerebral cortex  Clinical consciousness is defined on a continuum that grades levels of behavior  Alertness  drowsiness  stupor  coma (deep state of unconsciousness; do not respond to stimulus)

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Fainting  Brief loss of consciousness due to low blood pressure or sudden emotional stress

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Sleep  State of partial unconsciousness from which a person can be aroused by stimulation  Cortical activity is depressed  Brain stem functions continue

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Types of Sleep  There are two major types of sleep:  Non-rapid eye movement (NREM)  Rapid eye movement (REM)  One passes through four stages of NREM during the first minutes of sleep  Most nightmares occur here  REM sleep occurs after the fourth NREM stage has been achieved  Dreams occur here

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Sleep Disorders  Narcolepsy – lapsing abruptly into sleep from the awake state  Triggered by a pleasurable event  Insomnia – chronic inability to obtain the amount or quality of sleep needed  Sleep apnea – temporary cessation of breathing during sleep

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Memory  Memory is the storage and retrieval of information  Essential for learning and incorporation of experiences into behavior

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Memory Processing Figure 12.22

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Stages of Memory  The two stages of memory are short-term memory and long-term memory  Short-term memory (STM, or working memory) – a fleeting memory of the events that continually happen  STM lasts seconds to hours and is limited to 7 or 8 pieces of information  Long-term memory (LTM) has limitless capacity  Ability to store and retrieve decreases with age

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Transfer from STM to LTM  Factors that affect transfer of memory from STM to LTM include:  Emotional state – we learn best when we are alert, motivated, and aroused  Rehearsal – repeating or rehearsing material enhances memory  Association – associating new information with old memories in LTM enhances memory  Automatic memory – subconscious information stored in LTM

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Categories of Memory  The two categories of memory are fact memory and skill memory  Fact (declarative) memory:  Entails learning explicit information (names, faces, dates, words)  Is related to our conscious thoughts and our language ability  Is stored with the context in which it was learned

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Skill Memory  Skill memory is less conscious than fact memory and involves motor activity  It is acquired through practice (riding a bike, playing the piano, tying your shoes)  Skill memories do not retain the context in which they were learned

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Amnesia  Loss of memory caused by damage to the hippocampus  Varies in degrees depending on extent of damage

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Concussion  Occurs when there is a slight brain injury (blow to the head)  Symptoms are mild and short-lived  Dizziness, loss of consciousness  No permanent damage  Repeated concussions have a cumulative effect

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Cerebrovascular Accidents (Strokes)  Caused when blood circulation to the brain is blocked and brain tissue dies  Most commonly caused by blockage of a cerebral artery  Other causes include compression of the brain by hemorrhage or edema, and atherosclerosis  Transient ischemic attacks (TIAs) – temporary episodes of reversible cerebral ischemia  Tissue plasminogen activator (TPA) is the only approved treatment for stroke

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Degenerative Brain Disorders  Alzheimer’s disease – a progressive degenerative disease of the brain that results in dementia  Associated with ACh shortage & structural changes in the brain

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Degenerative Brain Disorders  Parkinson’s disease – degeneration of the dopamine-releasing neurons in certain regions of the brain  As the neurons deteriorate the target area of the brain that dopamine acts on are deprived of the chemical and now become hyperactive  Causes a persistent tremor, forward bending walking posture, a shuffling gait  Slow to initiate movements

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Spinal Cord Figure 12.29a

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Lumbar Tap Figure 12.30

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Spinal Cord Trauma: Paralysis  Localized damage to the spinal cord or its roots  Paralysis – loss of motor function  Paresthesias – sensory loss  Flaccid paralysis –  Lower motor neurons are damaged and impulses do not reach muscles  There is no voluntary or involuntary control of muscles (will atrophy)

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Spinal Cord Trauma: Paralysis  Spastic paralysis – only upper motor neurons of the primary motor cortex are damaged  Spinal neurons remain intact and muscles are stimulated irregularly  There is no voluntary control of muscles

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Spinal Cord Trauma: Transection  Cross sectioning of the spinal cord at any level results in total motor and sensory loss in regions inferior to the cut  Paraplegia – transection between T 1 and L 1  Affects lower limbs  Quadriplegia – transection in the cervical region  Affects all 4 limbs

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Amyotrophic Lateral Sclerosis (ALS)  Lou Gehrig’s disease – neuromuscular condition involving progressive destruction of motor neurons in brain and spinal cord  Muscles no longer receive signals – leads to paralysis  Symptoms – loss of the ability to speak, swallow, and breathe  Death occurs within five years