Nervous system notes

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Nervous system notes

  1. 1. The Nervous System Anatomy & Physiology Essentials of Human Anatomy & Physiology
  2. 2. <ul><li>Functions of the Nervous System </li></ul><ul><li>Sensory input – gathering information </li></ul><ul><ul><li>To monitor changes occurring inside and outside the body </li></ul></ul><ul><li>Integration - To process and interpret sensory input and decide if action is needed </li></ul><ul><li>Motor output </li></ul><ul><ul><li>A response to stimuli </li></ul></ul><ul><ul><li>Activates muscles or glands </li></ul></ul>
  3. 3. <ul><li>Classification of the Nervous System </li></ul><ul><li>Central nervous system (CNS): </li></ul><ul><ul><li>Brain </li></ul></ul><ul><ul><li>Spinal cord </li></ul></ul><ul><li>Peripheral nervous system (PNS): </li></ul><ul><ul><li>Nerves outside the brain and spinal cord </li></ul></ul>
  4. 4. <ul><li>The Peripheral Nervous System </li></ul><ul><li>Sensory (afferent) division - Nerve fibers that carry information to the central nervous system </li></ul><ul><li>Motor (efferent) division - Nerve fibers that carry impulses away from the central nervous system. </li></ul><ul><ul><ul><li>Somatic system : </li></ul></ul></ul><ul><ul><ul><li>voluntary </li></ul></ul></ul><ul><ul><ul><li>Autonomic system : </li></ul></ul></ul><ul><ul><ul><li>involuntary </li></ul></ul></ul>
  5. 5. <ul><li>Autonomic Nervous System </li></ul><ul><li>The involuntary branch of the nervous system </li></ul><ul><li>Consists of only motor nerves </li></ul><ul><li>Divided into two divisions </li></ul><ul><ul><li>Sympathetic division – “fight or flight” response </li></ul></ul><ul><ul><li>Parasympathetic division – “housekeeping” </li></ul></ul>
  6. 6. <ul><li>Nervous System Histology </li></ul><ul><li>Neurons = nerve cells </li></ul><ul><ul><li>Cells specialized to transmit electrochemical messages </li></ul></ul><ul><ul><li>Major regions of neurons </li></ul></ul><ul><ul><ul><li>Cell body – nucleus and metabolic center of the cell </li></ul></ul></ul><ul><ul><ul><li>Processes – fibers that extend from the cell body </li></ul></ul></ul>
  7. 7. <ul><li>Neuron Anatomy </li></ul><ul><ul><li>Dendrites – conduct impulses toward the cell body </li></ul></ul><ul><li>Cell body (soma): contains organelles & Nissl substance (specialized rough ER) </li></ul><ul><ul><li>Axons – conduct impulses away from the cell body </li></ul></ul><ul><ul><li>Schwann cells – produce myelin sheaths in jelly-roll like fashion </li></ul></ul><ul><ul><li>Nodes of Ranvier – gaps in myelin sheath along the axon </li></ul></ul>
  8. 8. <ul><li>Classification of Neurons </li></ul><ul><li>Sensory (afferent) neurons </li></ul><ul><ul><li>Carry impulses from the sensory receptors </li></ul></ul><ul><ul><ul><li>Cutaneous sense organs </li></ul></ul></ul><ul><ul><ul><li>Receptors – detect stretch or tension </li></ul></ul></ul><ul><li>Interneurons (association): “connector” </li></ul><ul><li>Motor (efferent) neurons </li></ul><ul><ul><li>Carry impulses from the central nervous system </li></ul></ul>
  9. 9. <ul><li>Neuron Classification </li></ul>Figure 7.6
  10. 10. <ul><li>Electrochemical Nerve Impulses </li></ul><ul><li>Dendrite depolarization – a stimulus depolarizes the dendrite’s membrane </li></ul><ul><li>Sodium (Na + ) flows inside the membrane with the help of Na+ pumps </li></ul><ul><li>This exchange of ions initiates an (+) action potential in the neuron </li></ul>
  11. 11. <ul><li>The Action Potential </li></ul><ul><li>If the action potential (nerve impulse) starts, it is propagated to the end of the axon </li></ul><ul><li>Potassium (K+) ions rush out of the neuron after sodium ions rush in, which repolarizes the membrane </li></ul><ul><li>The sodium-potassium pump restores the original configuration - which is resting potential (-) </li></ul><ul><ul><li>*** This action requires ATP *** </li></ul></ul>
  12. 12. <ul><li>Continuation of the Nerve Impulse between Neurons </li></ul><ul><li>Impulses are able to cross the synapse to another neuron </li></ul><ul><ul><li>Neurotransmitter is released from a neuron’s axon terminal </li></ul></ul><ul><ul><li>The dendrite of the next neuron has receptors that are stimulated by the neurotransmitter </li></ul></ul><ul><ul><li>An action potential is started in the dendrite </li></ul></ul>
  13. 13. <ul><li>How Neurons Communicate at Synapses </li></ul>Figure 7.10
  14. 14. <ul><li>The Reflex Arc </li></ul><ul><li>Reflex – rapid, predictable, and involuntary responses to stimuli </li></ul><ul><li>Reflex arc – direct route from a sensory neuron, to an interneuron, to an effector </li></ul>
  15. 15. <ul><li>Regions of the Brain </li></ul><ul><li>Cerebral hemispheres </li></ul><ul><li>Diencephalon </li></ul><ul><li>Brain stem </li></ul><ul><li>Cerebellum </li></ul>
  16. 16. <ul><li>Cerebral Hemispheres (Cerebrum) </li></ul><ul><li>Paired (left and right) superior parts of the brain </li></ul><ul><li>Include more than half of the brain mass </li></ul><ul><li>The surface is made of ridges (gyri) and grooves (sulci) </li></ul>
  17. 17. <ul><li>Specialized Area of the Cerebrum </li></ul>Figure 7.13c
  18. 18. <ul><li>Specialized Areas of the Cerebrum </li></ul>Figure 7.13c
  19. 19. <ul><li>Diencephalon </li></ul><ul><li>Sits on top of the brain stem </li></ul><ul><li>Enclosed by the cerebral hemispheres </li></ul><ul><li>Three parts: </li></ul><ul><ul><li>Thalamus </li></ul></ul><ul><ul><li>Hypothalamus </li></ul></ul><ul><ul><li>Epithalamus </li></ul></ul>
  20. 20. <ul><li>Brain Stem </li></ul><ul><li>Attaches to the spinal cord </li></ul><ul><li>Parts of the brain stem: </li></ul><ul><ul><li>Midbrain </li></ul></ul><ul><ul><li>Pons </li></ul></ul><ul><ul><li>Medulla oblongata </li></ul></ul>
  21. 21. <ul><li>Cerebellum </li></ul><ul><li>Two hemispheres with convoluted surfaces </li></ul><ul><li>Provides involuntary coordination of body movements </li></ul><ul><li>“ Arbor vitae” design of white & grey matter </li></ul>
  22. 22. <ul><li>Spinal Cord Anatomy </li></ul><ul><li>Extends from the medulla oblongata to the region of T12 </li></ul><ul><li>Below T12 is the cauda equina (a collection of spinal nerves) </li></ul><ul><li>Carries sensory and motor information </li></ul>Figure 7.18
  23. 23. <ul><li>Cranial Nerves </li></ul><ul><li>12 pairs of nerves that mostly serve the head and neck </li></ul><ul><li>Numbered in order, front to back </li></ul><ul><li>Most are mixed nerves, but three are sensory only </li></ul>
  24. 24. <ul><li>Cranial Nerves </li></ul><ul><li>I Olfactory nerve – sensory for smell </li></ul><ul><li>II Optic nerve – sensory for vision </li></ul><ul><li>III Oculomotor nerve – motor fibers to eye muscles </li></ul><ul><li>IV Trochlear – motor fiber to eye muscles </li></ul><ul><li>V Trigeminal nerve – sensory for the face; motor fibers to chewing muscles </li></ul><ul><li>VI Abducens nerve – motor fibers to eye muscles </li></ul>
  25. 25. <ul><li>Cranial Nerves </li></ul><ul><li>VII Facial nerve – sensory for taste; motor fibers to the face </li></ul><ul><li>VIII Vestibulocochlear nerve – sensory for balance and hearing </li></ul><ul><li>IX Glossopharyngeal nerve – sensory for taste; motor fibers to the pharynx </li></ul><ul><li>X Vagus nerves – sensory and motor fibers for pharynx, larynx, and viscera </li></ul><ul><li>XI Accessory nerve – motor fibers to neck and upper back </li></ul><ul><li>XII Hypoglossal nerve – motor fibers to tongue </li></ul>
  26. 26. <ul><li>Use a Mnemonic Device! </li></ul>“ On Old Olympus’ Towering Top A Fierce Viking Grew Vines and Hops”
  27. 27. <ul><li>Use a Mnemonic Device! </li></ul>“ Some say money matters but my brother says big brains matter more.”
  28. 28. <ul><li>The Brachial Plexus (Arm) </li></ul><ul><li>Spinal Nerves to know: </li></ul><ul><ul><li>Ulnar Nerve – Motor & Sensory, “the funny bone” </li></ul></ul><ul><ul><li>Radial Nerve – Motor & Sensory </li></ul></ul><ul><ul><li>Median Nerve – Motor & Sensory </li></ul></ul>
  29. 29. <ul><li>The Lumbrosacral Plexus (Leg) </li></ul><ul><li>Spinal Nerves : </li></ul><ul><ul><li>Sciatic – M,S </li></ul></ul><ul><ul><li>Femoral – M,S </li></ul></ul><ul><ul><li>Obturator – M,S </li></ul></ul><ul><ul><li>Tibial – M,S </li></ul></ul><ul><ul><li>Common Fibular – M,S </li></ul></ul>
  30. 30. “ You just nailed me in the head!” - Travis Bogumill (21) Eau Claire, WI 1998

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