Nervous System

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emilye
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192607
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Nervous System
Updated:
2013-01-13 18:01:55
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nerves anatomy
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Anatomy and Physiology: Nervous System
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  1. CNS (Central Nervous System)
    brain and spinal cord; serves as control center, information integration
  2. PNS (Peripheral Nervous System)
    sensory receptors and nerves

    • nerves connecting brain:12 pairs of cranial nerves
    • nerves connecting spinal cord: 31 pairs of spinal nerves
  3. Somatic PNS
    • monitor changes in external environment
    • has afferent and efferent nerves
  4. Autonomic PNS
    • helps regulate internal environment
    • has afferent and efferent nerves
  5. Afferent
    • sensory¬†nerves
    • transmit information to the CNS
  6. Efferent
    • motor nerves
    • transmit information from the CNS to effectors (muscles and glands)
    • sympathetic and parasympathetic
  7. Sympathetic Efferent Nerves
    usually stimulate organs
  8. Parasympathetic Efferent Nerves
    usually causes organs to slow or conserve energy
  9. Neuron
    structural and functional unit which receives and transmits info
  10. Glial Cells
    support cells of the nervous system (neuroglia)
  11. Oligodendrocytes
    forms sheaths made from myelin around the neurons
  12. Astrocytes
    provide structural support and also helps to form the blood-brain barrier
  13. Epidymal Cells
    lines the ventricles of the brain and canal of spinal cord
  14. Microglia
    has ability to destroy microorganisms
  15. Schwann Cells
    found in PNS, forms myelin sheaths around neurons
  16. cell body
    • contains the nucleus and many organelles
    • nissi substance (stains dark) functions in protein synthesis
    • neurofilaments provide support (may form lesions in certain degenerative brain diseases)
  17. dendrites
    • branches from the cell body, and carries impulses towards the cell body
    • forms synaptic connections with other neurons
  18. axon
    carries messages away from the cell body, may be several feet in length, also called a nerve fiber
  19. axon terminals
    found at the end of an axon, neurotransmitters are released to the next neuron
  20. Myelin
    • fatty substance, acts as an insulator, makes up plasma of Schwann Cells
    • phospholipid
  21. Nodes of Ranvier
    (nodes of ron-vee-ay)
    gaps between the schwann cells
  22. multipolar
    long axon, many dendrites (motor neuron)
  23. bipolar
    one dendrite, one axon (retina of eye, inner ear)
  24. unipolar
    single fiber functioning as both an axon and dendrite (most sensory neurons)
  25. A Reflex Arc
    • stimulus
    • reception
    • transmission
    • integration
    • transmission response (carried out by effectors)
  26. synapse
    junction between neurons or between a neuron and effector
  27. Sodium-Potassium Pump
    serves to maintain the unequal changes, K+ diffuses out much easier than Na+
  28. continuous conduction
    unmyelined neurons undergo continuous conduction
  29. salutatory conduction
    myelinated neurons utilize salutary conduction in which depolarization jumps from node to node, this type of conduction is much faster and requires less energy, skips over schwann cells
  30. Intensity of Sensation
    depends not upon the strength  of an impulse, but rather upon the number of neurons stimulated and the frequency of discharge
  31. Neuroglandular Junction
    between neuron and gland
  32. Myoneural Junction, Neuromuscular junction, motor end plate
    between neuron and muscle
  33. electrical synapses
    • pre + post synaptic neurons are very close together (2nm)
    • form gap junctions
  34. chemical synapses
    • pre + post synaptic neuron are separated by wider gaps (20 nm)
    • requires a neurotransmitter such as acetylcholine stored in synaptic vesicles
  35. excitatory postsynaptic potential (EPSP)
    brings neurons closer to firing
  36. Inhibatory postsynaptic potential (IPSP)
    takes neuron farther away from firing
  37. Common Neurotransmitters
    • acetylcholine
    • norepinephrine-in brain, may effect mood
    • dopamine-reduced levels in Parkinson's
    • serotonin-may play a role in sleep, LSD antagonizes serotonin
    • endorphins-helps suppress pain
  38. Nerve Fibers
    • classified by speed of conduction
    • an impulse can move both ways along an axon in the lab but they are unidirectional because there are no neurotransmitters in the dendrites
    • impulses can travel 400 feet/second
  39. Speed Increases with:
    • diameter of axon
    • amount of myelin
    • distance between nodes
    • fewer number of synapses
  40. Type A, B, C
    • Type A: largest diameter, fastest. (touch, pressure, pain)
    • Type B: medium sized, autonomic nervous system, much slower
    • Type C: smallest, slowest; impulses to smooth muscle, unmyelinated
  41. Convergence Circuts
    one neuron is controlled by two or more presynaptic neurons
  42. Divergence circuts
    one neuron stimulates many postsynaptic neurons
  43. Reverberating Circuts
    axons turned back upon themselves (a loop) allows for continuous discharge (rhythmic breathing)

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