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Peripheral Nervous System

P. e. r. i. p. h. e. r. a. l. N. e. r. v. o. u. s. S. y. s. t. e. m. S. k. e. l. e. t. a. l. A. u. t. o. n. o. m. i. c. (. S. o. m. a. t. i. c. ). S. y. m. p. a. t. h. e. t. i. c. P. a. r. a. s. y. m. p. a. t. h. e. t. i. c.

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Peripheral Nervous System

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  1. P e r i p h e r a l N e r v o u s S y s t e m S k e l e t a l A u t o n o m i c ( S o m a t i c ) S y m p a t h e t i c P a r a s y m p a t h e t i c Peripheral Nervous System

  2. Brain Sensory Neuron Motor Neuron Skin receptors Interneuron Muscle Somatic System • Nerves to/from spinal cord • control muscle movements • somatosensory inputs • Both Voluntary and reflex movements • Skeletal Reflexes • simplest is spinal reflex arc

  3. Autonomic System • Two divisions: • sympathetic • Parasympatheitic • Control involuntary functions • heartbeat • blood pressure • respiration • perspiration • digestion • Can be influenced by thought and emotion

  4. CENTRAL NERVOUS SYSTEM SYMPATHETIC Brain Dilates pupil Stimulates salivation Salivary glands Relaxes bronchi Spinal cord Lungs Accelerates heartbeat Heart Inhibits activity Stomach Pancreas Stimulates glucose Liver Adrenal gland Secretion of adrenaline, nonadrenaline Kidney Relaxes bladder Sympathetic ganglia Stimulates ejaculation in male Sympathetic • “ Fight or flight” response • Release adrenaline and noradrenaline • Increases heart rate and blood pressure • Increases blood flow to skeletal muscles • Inhibits digestive functions

  5. CENTRAL NERVOUS SYSTEM PARASYMPATHETIC Brain Contracts pupil Stimulates salivation Constricts bronchi Spinal cord Slows heartbeat Stimulates activity Stimulates gallbladder Gallbladder Contracts bladder Stimulates erection of sex organs Parasympathetic • “ Rest and digest ” system • Calms body to conserve and maintain energy • Lowers heartbeat, breathing rate, blood pressure

  6. Autonomic nervous system controls physiological arousal Sympathetic division (arousing) Parasympathetic division (calming) Pupils dilate EYES Pupils contract Decreases SALIVATION Increases Perspires SKIN Dries Increases RESPIRATION Decreases Accelerates HEART Slows Inhibits DIGESTION Activates Secrete stress hormones ADRENAL GLANDS Decrease secretion of stress hormones Summary of autonomic differences

  7. Brain Spinal Cord Central Nervous System • Brain and Spinal Cord

  8. Corpus Callosum Right Hemisphere Left Hemisphere Brain has 2 Hemispheres • Left & Right sides are separate • Corpus Callosum : major pathway between hemispheres • Some functions are ‘lateralized’ • language on left • math, music on right • Lateralization is never 100%

  9. Frontal Parietal Occipital Temporal Each hemisphere is divided into 4 lobes

  10. Left visual field Right visual field Optic nerves Left Visual Cortex Corpus Callosum Right Visual Cortex Sensory Information sent to opposite hemisphere • Principle is Contralateral Organization • Sensory data crosses over in pathways leading to the cortex • Visual Crossover • left visual field to right hemisphere • right field to left • Other senses similar

  11. Motor Cortex Somatosensory Cortex Contralateral Motor Control • Movements controlled by motor area • Right hemisphere controls left side of body • Left hemisphere controls right side • Motor nerves cross sides in spinal cord

  12. Medial surface of right hemisphere Corpus Callosum Corpus Callosum • Major ( but not only) pathway between sides • Connects comparable structures on each side • Permits data received on one side to be processed in both hemispheres • Aids motor coordination of left and right side

  13. Corpus Callosum • What happens when the corpus callosum is cut? • Sensory inputs are still crossed • Motor outputs are still crossed • Hemispheres can’t exchange data

  14. Verbal left hemisphere Nonverbal right hemisphere The ‘Split Brain’ studies • Surgery for epilepsy : cut the corpus callosum • Roger Sperry, 1960’s • Special apparatus • picture input to just one side of brain • screen blocks objects on table from view

  15. “What did you see?” “Using your left hand, Pick up what you saw.” “What did you see?” ?? I saw an apple. Verbal left hemisphere Nonverbal right hemisphere Verbal left hemisphere Nonverbal right hemisphere The ‘Split Brain’ studies • Picture to left brain • can name the object • left hand cannot identify by touch • Picture to right brain • can’t name the object • left hand can identify by touch

  16. Frontal Parietal Occipital Temporal Localization of function

  17. Occipital Lobe • Input from Optic nerve • Contains primary visual cortex • most is on surface inside central fissure • Outputs to parietal and temporal lobes Occipital Lobe Visual Lobe

  18. Auditory Cortex Temporal Lobe Temporal Lobe Temporal Lobe • Contains primary auditory cortex • Inputs are auditory, visual patterns • speech recognition • face recognition • word recognition • memory formation • Outputs to limbic System, basal Ganglia, and brainstem

  19. Somatosensory Cortex Parietal Lobe Parietal Lobe • Inputs from multiple senses • contains primary somatosensory cortex • borders visual & auditory cortex • Outputs to Frontal lobe • hand-eye coordination • eye movements • attention

  20. Frontal Lobe Working Memory Motor Cortex Motor Cortex Motor Cortex Broca’s Area Frontal Lobe • Contains primary motor cortex • No direct sensory input • Important planning and sequencing areas • Broca’s area for speech • Prefrontal area for working memory

  21. Frontal Lobe Disorders • Broca’s area • productive aphasia • Prefrontal area • lose track of ongoing context • fail to inhibit inappropriate responses • Often measured with the Wisconsin Card Sorting Task

  22.  A sagittal section through the human brain

  23. Subcortical Structures Medulla-controls vital reflexes like breathing, heart beat, etc Pons- many fibers cross Reticular formation- arousal, attention Raphe system- wakefulness Cerebellum- movement, shifts of attention, balance and coordination

  24. Subcortical Structures - Thalamus Relay Station for Sensory Information - Hypothalamus Regulates homeostasis, sexual behavior, fighting, feeding, controls Pituitary Gland

  25. Subcortical Structures - Cerebellum motor learning, balance, attention shifts - Limbic System - Basal Ganglia

  26.  The limbic system is a set of subcortical structures that form a border (or limbus) around the brain stem

  27. Central Nervous System Peripheral Nervous System The Nervous System: Summary • Major structures of the nervous • CNS, Somatic, Autonomic • Two hemispheres & 4 lobes • Organization • contralateral input & output • primary sensory areas • motor areas • Commissure • Localization of functions

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