Nervous Tissue Pt. 2

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Author:
lnguye10
ID:
114960
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Nervous Tissue Pt. 2
Updated:
2011-11-06 18:33:14
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nervous tissue
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Description:
A&P exam 3
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  1. Postsynaptic Cell Responses:
    • 1) Open/close membrane ion channels
    • - depolarization
    • - hyperpolarization

    • 2) Variety of intracellular responses
    • - Result depends on type of NT and the receptor type for each NT
  2. postsynaptic potentials
    - types? describe.
    • 1. Graded potentials
    • 2. EPSP = excitatory postsynpatic potential
    • - opens Na+ and K+ chemical-gated channels simultaneously
    • - Na+ influx> K+ efflux
    • - Depolarization (closer to threshold)

    • 3. IPSP= inhibitory postsynaptic potential
    • - NT binding causes hyperpolarization
    • - Opens K+ and/or Cl- chemical-gated channels
    • -K+ efflux and/ or Cl- influx
    • - Hyperpolarization- farther away from threshold.
  3. Summation
    - 2 methods, describe
    • #1. Spatial summation 9 uses multiple neurons to cause a larger effect on the postsynaptic neuron)
    • --> simultaneous graded potentials to enhance initiation of a potential at trigger zone.

    • #2. Temporal Summation (over time you increase the frequency of stimulation)
    • --> Graded potentials arrive at trigger zone very close together
  4. Types of Summation: Processes
    * postsynaptic neuron (at axon hillock) - integrator of excitatory inhibitory signals:

    • - Excitatory >Inhibitory, but < Threshold = Facilitation
    • - Excitatory> inhibitory, and Threshold = AP
    • - Inhibitory> Excitatory= Inhibition
  5. Presynaptic Inhibition/Facilitation
    • -NT release froma axon terminals of presynaptic neuron is inhibited or stimulated
    • - Change in postsynaptic membrane response
  6. Synaptic Integration (5)
    • - Different Patters of interactions between enurons
    • 1. Divergence
    • (EX) sensory info is distributed to various parts of the brain at the same time.

    • 2. Convergence
    • (EX) Multiple parts of the brain control the function of one neuron

    • 3. Serial processing
    • (EX) sensory info is relayed from one part of the brain to another in sequence.

    • 4. Parallel processing
    • (EX) Simultaneous processing; multiple responses at the same time

    • 5. Reverberation
    • (EX) positive feedback that continues until synaptic fatigue occurs or something breaks the cycle.
  7. Signal Termination
    • 1. Uptake into presynaptic cell (or adjacent neuron or glial cells)
    • 2. Enzymatic inactivation
    • 3. Diffusion of NT away from synapse

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