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The Nervous System

The Nervous System. I. General organization of nervous system. CNS 1. brain 2. spinal cord B. PNS 1. sensory 2. motor a. Somatic b. ANS -sympathetic -parasympathetic. II. Nervous Supporting Cells - neuroglia. Astrocytes

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The Nervous System

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  1. The Nervous System

  2. I. General organization of nervous system • CNS 1. brain 2. spinal cord B. PNS 1. sensory 2. motor a. Somatic b. ANS -sympathetic -parasympathetic

  3. II. Nervous Supporting Cells - neuroglia • Astrocytes • Connect to capillaries • Mopping up chemical environment of brain as far as potassium ions and neurotransmitters

  4. B. Microglia • 1. spider-like phagocytes • 2. debris, dead brain cells, bacteria

  5. C. Ependymal cells • 1. lines cavities in CNS • 2. beating of cilia moves cerebrospinal fluid • 3. fluid nourishes and cushions CNS

  6. D. Oligodendrocytes • 1. wrap axons of nerve cells with fatty layer • 2. produces myelin sheath • 3. speeds conduction

  7. E. Glia cells in general • 1. resemble neurons • 2. not excitable • 3. supportive cells • 4. capable of repeated mitosis • 5. gliomas-glial tumors

  8. III. NeuronsA. Structure • 1. cell body • 2. nissl bodies-rer • 3. dendrites • 4. axon • 5. axon hillock • 6. axon collateral • 7. axon terminals • 8. neurotransmitters • 9. synaptic cleft

  9. B. Myelin sheath • 1. functions • 2. PNS-Schwann cell • 3. Node of Ranvier • 4. Can form a pathway for regrowth of damaged axon • 5. multiple sclerosis

  10. C. Neurons classified by function • 1. afferent • 2. interneuron • 3. efferent • 4. ganglia • 5. nuclei

  11. D. Neurons classified by structure • 1. multipolar • 2. bipolar • 3. unipolar

  12. IV. Neuron physiology • A. Resting membrane potential • B. Action potential-nerve impulse

  13. C. Propagation of action potential • 1. diagram on board • 2. a lot like dominoes • 3. http://www.youtube.com/watch?v=7tBWl4GE8rk&NR=1

  14. D. Anatomy of a synapse • 1. presynaptic membrane • 2. synaptic cleft • 3. postsynaptic membrane • 4. synaptic vesicles • 5. receptor sites for transmitter substance

  15. E. Physiology of synapse • 1. action potential arrives • 2. Calcium ion channels open • 3. synaptic vesicles fuse with membrane • 4. transmitter substance released • 5. diffusion of transmitter substance • 6. binding to receptors • 7. creates a graded potential • 8. may bring postsynaptic membrane to threshold • 9. nerve gas-blocks cholinesterase

  16. F. You tube of synaptic events • http://www.youtube.com/watch?v=z3F5dfmQ3hk

  17. V. Functional Anatomy of the Brain A. Introduction • 1. difficult to talk about • 2. two fistfuls of pinkish/gray • 3. wrinkled • 4. consistency of cold oatmeal • 5. three pounds • 6. hugely complex • 7. four basic regions • a. Cerebral hemispheres • b. Diencephalon • c. Brain stem • d. cerebellum

  18. B. Cerebral hemispheres • 1. most important part • 2. overshadows diencephalon and brain stem • 3. mushroom cap covers top of stalk • 4. gyri • 5. sulci • 6. fissures-ie longitudinal cerebral fissure

  19. 7. Lobes of cerebrum • a. Frontal lobe controls mainly motor function • b. Primary motor area is on the precentralgyrus -governs conscious motor control which can be mapped

  20. Motor homunculus

  21. c. Motor homunculus • -specific regions of the precentralgyrus control specific body parts • -finer the movements, the more brain area needed to control those movements

  22. d. Premotor area • -learned repetitive tasks • Typing, playing piano • Athletes learn tasks by visualizing motions • Ingrained in this area

  23. e. Broca’s area • speech center • Usually located left cerebral hemisphere • Damage here causes inability to speak

  24. 8. Other important areas of cerebral hemispheres • a. Primary somatic sensory area • b. Visual area in occipital lobe • c. Complex memory in the temporal lobe • d. Note close proximity to olfactory area • e. Anterior association area-higher intellectual reasoning and socially acceptable behavior

  25. 9. Sensory homunculus

  26. C. Diencephalon • Thalamus a. Encloses third vent. b. Screens incoming sensory messages • Hypothalamus a. ANS center for body temperature and water balance b. Regulates pituitary • Epithalamus a. Pineal gland b. Choroid plexus

  27. D. Brain stem • 1. size of thumb • 2. midbrain • 3. pons • 4. medulla • 5. interchange for sensory and motor paths • 6. nuclei for respiratory, blood pressure, heart rate, RAS

  28. E. Cerebellum • Cauliflower shape • Controls balance and equilibrium • Produces smooth and coordinated muscular contractions

  29. VI. Protection of the brain • A. Meninges • 1. dura mater • 2. arachnoid • 3. pia mater • B. CSF • 1. produced choroid plexi • 2. flow • 3. functions • 4. hydrocephalus

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