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2011-02-09 13:55:44


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  1. Two catergine of synapses
    Electrical and chemical. Majority of synapses in human brain are chemical
  2. Electrical synapses?
    • Direct transfer of current from one cell to the next
    • -current goes throught gap junctions
    • -each channel=connexon
    • -connexons made up of connexin proteins
  3. Gap junction?
    addtion of connexon
  4. PSP is
    post synaptic poential. Small compared to action potential is 1mv
  5. Electrical synapses are
    Bidirectional. Fast- no time delay . Ex escape reflexes in invertebrates
  6. presynaptic side
    axon terminal with synaptic vesicles- store neurotransmitter
  7. Post synaptic side
    neurotransmitter receptors
  8. SNARE proteins
    attach the synaptic vesicle to active zone.
  9. synaptic vesicle docked at, and process
    • presyneptic membrance by snare protiens. Acton potential arrives at axon terminal
    • -voltage gated calcium channels open
    • -calcium flows into presynaptic terminal
    • vesicle fuses w/ presynaptic membrane
    • -nerotransmitter released.
    • vesicle recycled
  10. synaptotagnin is
    • SNARE PROTEIN on synaptic vesicle
    • - senses ca2+ increase and triggers release
  11. what does tetanus toxin do?
    Tetanus toxin released by bacteria has its effect by cutting snare protein.
  12. Neuromusculare junction
    synapse between neuron + muscle cell
  13. Motor end plate=
    • post-synaptic membrance-
    • -is folded
    • -larger surface area
    • -many neuro-transmitter receptors
  14. synaptic vesicle
    • aligned over folds
    • -release of a large number of neurotransmitter molecules
    • -large response in muscle cell to contraction
    • -fail -safe
  15. excitatory neurotransmitter example
  16. At postsynaptic terinal after diffusing across synaptic clef what happens?
    Neurontransmitter binds to neuro transmitter gated ion channels and then ion channel opens and if channel permeable to Na+ ions then EPSP(excitatory postsynaptic potential)
  17. Inhibitory neurotransmitter example
  18. Chemical synapses can be
    inhibitory if neurotransmitter-gated ion channel is permable to CL- ions then IPSP (inhibtory post-synaptic potential)