Physiology Exam 2

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  1. Structure of neurons include...(5)
    • Soma
    • Axon
    • Dendrites
    • Myelin Sheath
    • Nodes of Ranvier (Ron-Vee-Ay)
  2. Soma
    Body of perikaryon
  3. Axon (2)
    • Conducts nerve impulses away from soma
    • Never more than one axon per neuron(some have none)
  4. Dendrites
    receive impulses from other neurons
  5. Myelin Sheath (4)
    • Insulating layer (mostly lipid) around nerve fibers, which are formed by
    • neuroglia cells(Schwann Cells in PNS & Oligodendrocytes in CNS).
    • Not all nerve fibers are myelinated.
    • Myelinated comprise the white matter.
    • Unmyelinated comprise the gray matter.
  6. Nodes of Ranvier (2)
    • Myelinated nerve fibers
    • Ions can be exchanged with the ECF only with this...
  7. Types of Neurons (4)
    • Sensory(afferent)
    • Interneurons(association neurons)
    • Motor(efferent)
    • Reflex Ark
  8. Sensory (afferent)
    Conduct impulses toward the CNS
  9. Interneurons (association neurons) (2)
    • Entirely within the CNS
    • Conduct impulses from sensory neurons to motor neurons.
  10. Motor (efferent)
    Conduct impulses away from the CNS and to the effectors (muscles or glands).
  11. Reflex Ark is an arrangement of...(3)
    • sensory neurons
    • interneurons
    • motor neurons
  12. Functions of Neurons (3)
    • Excitability (irritability)
    • Conductivity
    • Secretion of neurontransmitters
  13. Nervous Tissue is specialized (2)Consists of? (2)
    • Communication, by means of electrical or chemical signs
    • neurons (nerve cells)
    • neuroglia (glial cells)
  14. Interior of nerve cell or any cell is...? Relative to ECF. (3)
    • Polarized
    • Negative Charge
    • Requires ATP
  15. The charge differences across the plasma membrane is...? which is about...?
    • Resting Membrane Potential (RMP)
    • -70mV
  16. The...charge of the ion in cell.
    Ex: -70
  17. Large anions that cannot escape cell Na+ is ...x higher concentration outside. K+ is ...x higher concentration inside.
    • 12
    • 4
  18. Uneven distribution of Na+ & K+ on ... of plasma membrane pertains only to thin film of ions adjacent to the membrane surface.
    Two sides
  19. Electrical events involves ions adjacent to membrane in...?
    Either side
  20. Local Potentials (3)
    • Influx of Na+ diffuse for a short distance along the inside of plasma membrane
    • Produce a current that travels from point of stimulation toward the cell's trigger zone; short range change
    • High need of glucose and ATP energy
  21. Characteristics of Local Potentials
    • Stimulation of neuron by chemical, light, heat, mechanical distortion.
    • Stimulation alters permeability of various ions thus leading to a change in resting membrane potential
    • Graded-different magnitude
    • Decremental-die out
    • Reversable
  22. Action Potential (2)
    • Occur where there is high density of voltage gated channels, ex: trigger zone has 350 to 500 channels/μm2.
    • Generated if local potential spreads all the way tot he trigger zone and is still strong, it can open these channels.
  23. The action potential changes the membrane potential from -70mV (resting) to 35mV & back again to the resting membrane potential. (7)
    • The action potential arrives at the axon hillock, depolarizes the membrane at that point.
    • This local potential must rise to a critical voltage called threshold ~ -55mV.
    • The neuron now produces an action potential.
    • As potential passes 0mV the Na+ channel closes, the voltage peaks @ +35mV, as the voltage peaks the K+ channels open K+ ions exit the cell.
    • Their outflow repolarizes the membrane.
    • Hyperpolarization, membrane voltage drops 1 or 2mV more negative because K+ channels stay open longer than Na+ channels, so more K+ leaves the cell than the amount of Na+ entered.
    • Refractory Period, for a short time, few milliseconds, after action potential, it is impossible to stimulate that region of a neuron to fire again; This is the period of resistance to restimulate.
  24. All or Nothing Law
    Action Potentials are non decremental
  25. There are 2000 to 12000 voltage gated ion channels/μm2 at...?
    The node of ranvier
  26. In..., ions can be exchanged with the ECF only at the Nodes of Ranvier.
    Myelinated nerve fibers
  27. Saltatory Conduction
    Impulses jumping from node to node.
  28. Synaptic Knob
    Pre-synaptic neuron
  29. Synaptic Vesicles
    (Filled w/neurotransmitters) in the pre-synaptic neuron
  30. Neurotransmitter receptors
    In the post-synaptic membrane
  31. Cessation of signal at the synapse (3)
    • Re uptake of the neurotransmitter by the pre-synaptic neuron
    • Diffusion of the neurotransmitter into the extracellular fluid, where astrocytes absorb it.
    • Degradation of the neurotransmitter in the synaptic cleft.
  32. Muscle contraction (3)
    • Muscle relaxation
    • Molecular processes involving muscle contraction
    • General structure & functions of different muscle cells
  33. Smooth Muscles (4)
    • Elongated
    • Spindle-shaped Fiber
    • Single Nucleus
    • Involuntary
  34. Cardiac Muscles (5)
    • Branched
    • Striated Fiber
    • Single Nucleus
    • Intercalated disks
    • Involuntary
  35. Skeletal Muscles (3)
    • Multinucleated
    • Striated Cylindrical Fiber
    • Voluntary Movement
  36. Myofilaments
    • Myosin (thick) filaments
    • Actin (thin) filaments, tropomyosin & troponin are associated w/thin filaments
    • Titin (elastic) filaments
  37. Motor Units
    • Spinal Cord, motor neuron 1, motor neuron 2
    • Neuromuscular junction
    • Skeletal Muscle Fibers
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Physiology Exam 2
2014-02-17 22:00:12

Exam 2
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