A & P

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A & P
2010-12-11 17:10:42
Nervous System Chp

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  1. Formation of the Central Nervous System (CNS)?
    • Neural tube forms and sinks below surface
    • a. forward end forms brain
    • b. back end forms spinal cord
    • fluid filled cavity becomes central canal and ventricles
    • Cerebral Spinal Fluid (CSF)
  2. Neurology:
    • study of nervous system
    • is a control system: communicates with and controls other sytems
  3. CNS
    Brain and Spinal Cord
  4. Peripheral Nervous System (PNS)
    • Sensory (afferent carry toward) Division
    • a. nerve fibers (axons) that convey impulses to the CNS from sensory receptors
    • Motor (efferent carry away) Division
    • a. transmits impulses from the CNS to effector organs
    • b. two subdivisions
  5. Motor division of PNS subdivisions:
    • Somatic Nervous System
    • a. skeletal muscle
    • b. "voluntary nervous system"
    • c. somatic motor nerve fibers
    • Autonomic Nervous System (ANS)
    • a. regulate the activity of smooth and cardiac muscle and glands
    • b. "involuntary nervous system"
    • c. visceral motor nerve fibers
  6. Functional subdivisions of the ANS?
    • Sympathetic Nervous System
    • a. "Fight or Flight"
    • Parasympathetic Nervous System
    • b. slows down body
  7. Cells of the Nervous system:
    • Neurons: functional and structural units of NS
    • Neuroglia: accessory support and protective cells for neurons, function much like c.t. in other parts of body
  8. Neuroglia in PNS
    Schwann cells- provide insulation on axon
  9. Neuroglia in CNS
    • Astrocyte: interface nerve tissue and blood vessel
    • Oligodendrocyte: provide myelin sheath
    • Microglia: active and increase in number during inflammation of CNS
    • Ependyma: form an epithelial like membrane that is one cell thick and covers inside spaces within brain (ventricles, central canal), important in the blood-brain barrier: choroid plexus= capillary network associated with ventricles
  10. Neurons: cannot divide but may generate new branch. Three Basic parts:
    • Cell Body:
    • a. makes neurofibrils for transporting material around neuron.
    • b. centrosome (mitotic apparatus) missing
    • Dendrite:
    • a. short, numerous, highly branched fibers from cell body
    • b. carry impulses to cell body
    • Axon:
    • a. usually one, long, larger, uniform in diameter process from cell body
    • b. carry impulse away from cell body
    • c. hillock-where leaves cell
    • d. collateral-branches of axon
    • e. ends specialized for synapse with another cell (presynaptic terminal)
  11. Functional Classification of Neron:
    • Sensory (afferent): to CNS
    • Motor (efferent): away from CNS; to effector (muscle or gland)
    • Association (interneuron): totally in CNS, between sensory and motor neurons, 90% are in this catergory
  12. Structural Classification of Neuron:
    • Unipolar: one process from cell body
    • ex. in ganglia of spinal nerves
    • Bipolar: two processes from cell body. 1 axon 1 dendrite
    • ex. special sensory- eyes, nose, ears
    • Multipolar: one axon and may dendrites
    • ex. in brain most are this type
  13. Gap in an axon myelinated sheath?
    Node of Ranvier
  14. White Matter?
    Dense collection of myelinated fibers and axon.
  15. Grey Matter?
    Mostly nerve cell bodies and dendrites
  16. Tract? Nerve?
    • a. collection of neuron fiber inside CNS
    • b. collection of neuron fiber outside CNS
  17. Endoneurium:
    c.t around one neuron
  18. Perineurium:
    c.t. around bundle of neurons
  19. Epineurium:
    c.t. around all fibers; contains blood vessels, fat
  20. Nerves:
    • a. Sensory
    • b. Motor
    • c. Mixed
  21. Spinal Nerves?
    nerves originating from spinal cord that communicate with other body parts
  22. Cranial Nerves?
    originating from the brain that communicate with other body parts
  23. Ganglia?
    collection of neuron cell bodies outside the CNS
  24. Nuclei?
    collection of neuron cell bodies inside the CNS
  25. Synapse?
    • a junction between two cells
    • ex. nerve-nerve, nerve-muscle, nerve-gland
  26. Presynaptic cell?
    before the gap
  27. Postsynaptic cell?
    after the gap
  28. Synaptic Cleft?
    gap between cells
  29. Types of Synapse?
    • Electrical: proteins actually embedded in both cell membranes, provide channels for ion flow.
    • Chemical: most fit in this category, axon with synaptic bulb that contain vesicle with neurotransmitters
  30. Synaptic delay?
    time required to actually cross cleft (about .5 msec)
  31. Synaptic fatigue?
    depletion of neurotransmitters in vesicles, cannot synthesize fast enough
  32. Curare?
    • competes for Ach receptor sites
    • inhibits contraction
  33. Diisopropyl fluorophosphate / neostigmine / physostigmine?
    combine with acetylcholinesterase and deactivates it: this allows continued contraction and leads to spasm
  34. Botulin Toxin?
    inhibits Ach release
  35. Caffeine / benzedrine / nicotine?
    reduce threshold for excitation and therefore result in facilitation