EXSS 276 1st EditionExam # 3 Study Guide Lectures: 16-22Nervous System: The BrainBrain Facts- Makes up 2% of adult weight, but uses 20% of glucose and oxygen- Brief interruptions of oxygen can cause loss of consciousnesso 1-2 minutes = neuron dysfunctiono 3-4 minutes = permanent damage- Brain uses glucose; has no glucose storageo Interruptions in glucose supply causes confusion, convulsions, loss of consciousnessBrain Stem- Midbraino Relays motor output from cerebral cortex to ponso Sends sensory input from spinal cord to thalamus- Ponso Relays impulses from one side of cerebellum to the othero Relays impulses from medulla to midbraino Regulates breathing- Medullao Relays sensory input and motor output between brain and spinal cordo Consciousness and arousalo Regulates heartbeat, blood vessel diameter, breathing o Site of Decussation = cross over Cerebellum- Compares intended to actual movement- Coordinator- Regulates posture and balance- Complex movements (learning/storage/recall)Diencephalon- Thalamuso Built to send signalso Relays sensory input to cerebral cortexo Helps plan and control movementso Perceives touch, pressure, vibration, pain, temperature- Hypothalamuso Controls and integrates ANS and pituitary gland o Emotion and behavioro Body temperature, eating, drinking, sleepo Hormones associated with posterior pituitary but ADH and oxytocin- Epithalamuso Pineal gland which secretes hormones – melatonin (helps regulate sleep-wake cycles)Cerebrum- Sensory areas: perceive sensory info- Motor areas: plan and initiate muscular movements- Association areas: memory, personality, intelligence- Basal ganglia: coordinate gross movements and muscle tone (do not directly send signalsto or directly receive signals from spinal cord)- Limbic system: emotion, survival, amygdala = fearBasal Ganglia- Putamen and caudate nucleuso Receive sensory and motor input from cerebral cortex – sends to globus pallidus - Globus palliduso Gives output, sends feedback signals to motor cortex via thalamus - Regulates initiation and termination of movements - Damage to it results in uncontrollable shaking, involuntary movement (Parkinson’s disease)Cerebral Cortex Areas- Primary somatosensory areao Postcentral gyruso Size of cortical area = dependent on neuronso Provides sensory info for movement planning and modification- Somatosensory association areao Personal will, memory, judgment (higher emotion)o Posterior parietal: interprets sensory info so movement is consistent w/ environment- Premotor areao Anticipationo Correct orientation prior to movemento Sensory guidance of limbso Active during learning- Supplementary motor areao Plans movements and muscle sequencing – 2 handed actions- Primary motor areao Precentral gyruso Synthesize info from CNSo Initiates central commando Specifies muscles contraction force, and timing; trunk muscle control- Somatic sensory and motor maps in cerebral cortexo Homunculuso Size of region = proportional to number of specialized sensory receptorsIntegration of Sensory and Motor Info- Local circuit neuronso Input from somatic sensory receptors as well as higher brain centerso Help coordinate rhythmic activity (walking)- Upper motor neuronso Synapse w/ local circuit and lower motor neuronso Originate from cerebral cortex (voluntary movements) or motor centers in brain stem (posture, balance, tone)- Basal ganglia neuronso Provide input to upper motor neurons (which go to local neurons which go to lower motor neurons)o Synapse w/ motor areas of cerebral cortex via thalamus and brain stemo Initiates and terminates movements, suppresses unwanted movements, tone (Parkinson’s)- Cerebellar neuronso Control activity of upper motor neuronso Connect w/ cerebral motor cortex via thalamus and brain stemo Monitors difference between intended and actual movements, then communicates w/ upper motor neurons to make adjustments- Corollary discharge: tells the rest of the brain what’s going on Summary of Integration Centers- Spinal cord: simple motor reflexes- Lower brain stem: more complex subconscious motor reactions such as postural control- Cerebellum: subconscious control of movement such as those needed to coordinate multiple movements- Thalamus: conscious distinction among sensations such as feeling hot or cold- Cerebral cortex: perceive sensory info, conscious movements Conscious Control of Movement- Primary motor cortex (cerebrum): plans and initiates voluntary muscle movement- Basal ganglia (cerebrum): sustained and repetitive movements, initiation and termination of movements- Cerebellum: intention versus actual movement, posture and balance, corrections, fast and complex movement- Memorized motor patterns stored in brain (engrams)- Motor areas in right hemisphere control muscles in left hemisphereo Decussation occurs in medulla (90% cross over)Learning and Memory- Learning: ability to acquire new info or skills via instruction or experience- Memory: info acquired via learning is stored and retrievedo Must produce structural and functional changeso Plasticity of the braino Limbic system, hippocampus, amygdala, diencephalon, primary somatosensory, primary motor areaso Immediate (few seconds)o Short-term (seconds to minutes)o Long-term (days to years) – memory consolidationo Motor skill memories: basal ganglia, cerebellum, cerebral cortex Muscle PhysiologyOverview: Types of MuscleSkeletal- Attached to bones- Striated- Voluntary- MultinucleatedCardiac- Forms wall of heart- Striated- Involuntary- Uni-nucleatedSmooth (visceral)- Located in viscera- Non-striated- Involuntary- Uni-nucleatedFunctions of Muscle Tissue- Produce body movements- Stabilize body positions- Regulate organ volumeso Bands of smooth muscle called sphincters- Movement of substances w/in the bodyo Blood, lymph, urine, air, food and fluids, sperm- Produce heato Involuntary contractions of skeletal muscle (shivering)Properties- Excitabilityo Ability to respond to stimuli and produce electrical signalso Auto-rhythmic electrical signalso Chemical stimuli: hormonal responses, neurotransmitters- Contractilityo Ability to shorten and generate force once excited- Extensibilityo Ability to stretch without damaging tissue Smooth and cardiac mostly- Elasticityo Ability to return to normal length after being extended- Thermalo Ability to produce heat energySkeletal Muscle-