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2010-10-28 13:31:45
Chap Synaptic transmission

chap 8 synaptic transmission
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  1. describe the anatomy of a neuron synapse and all the steps of a synaptic transmission at a neuron synapse

    Use the illustration below:
    • 1. neuron picks up stimilus. goes through 3 neurons before brain interprets
    • 2. action potential causes depolarization. opens calcium channels
    • 3. exocytation, release transmitter
    • 4. neurotransmitter binds to post depolarization
    • 5. graded potential
    • 6. enzyme breakdown
    • 7. reutilization of neuro-transmitter
    • 8. diffusing away
  2. define characteristics of a synapse
    • 1. one way transmission
    • 2. summation. Required to reach threshold
    • 3. inhibition as well as stimulation occurs
    • 4. divergence and convergence
    • 5. fatigue (vesicle neurotransmitter supply can exhaust)
    • 6. slow "synaptic delay" caused by diffusion process
    • 7. drug action possible
  3. describe EPSP's (excitatory postsynaptic potentials)
    • when an excitatory synapse brings the membrane potential of the post synaptic neuron closer to the threshold for generating an action potential. Excitatory synapses depolarize the post synaptic neuron.
    • this depolarization is called an epsp excitatory postsynaptic potential.
  4. describe a fast EPSP
    channel linked receptor
    • caused by the binding of neurotransmitter molecules to their channel linked receptors. ion moves through rapidlly
    • sodium ions enter, potassuim ions leave
    • sodium movement is greater
    • net effect is depolarization
  5. describe slow EPSP
    Slow response is mediated through G protien-linked receptors.

    • direct coupling opens or closes channels, or secondary messenger system (g protien) opens or closes ion channels
    • uses phosphorylation of a potassium channel
    • decrease leakage of potassium out of cell
    • net effect same as fast, that is depolarition
  6. define inhibitory postsynaptic potential IPSP
    • graded potentials
    • Hyperpolarize the post synaptic membrane
    • take membrane potential farther away from threshold for an action potential
    • can occur by:
    • closing sodium channels
    • opening potassium channels
    • opening chloride channels
  7. define frequency coding
    the degree of depolarization does not affect the size of action potentials but rather their frequency

    • increases in strength of suprathreshold stimuli cause the frequency of action pot. to increase=
    • frequency coding
    • when action pot. occur at higher frequency more neurotransmitter is released from neuron
  8. describe the neurotransmitter Acetylcholine, where is located and types of receptors it binds to
    acetylcholine is released from neurons both in the central and preriferal nervous systems

    • binds to multiple cholinergic receptors
    • Nicotinic cholinergic receptors
    • Muscarinic cholinergic receptors
  9. Describe Nicotinic Cholinergic Receptors
    • Direct fast acting
    • cause excitiory postsynaptic potentials EPSP
    • Located on skeletal muscle cells
    • both sympathetic and parasymnpathic
    • Adrenal Medulla
  10. describe muscarinic cholinergic receptors
    • need G protien ie. Slow response
    • can open/close ion channels OR activate enzymes
    • located on effector organs innervated by parasympathetic Nervous system
    • -Heart slows heart rate
    • -smooth muschle of digestive tract
    • -smooth muscles controling the constriction of the pupil of the eye
  11. what is the role of epinephrine/norepinephrine?
    • binds to adrenergic receptors.
    • Alpha -a1, a2,
    • beta 1,2,3
    • receptors found in CNS and effector organs of sympathetic nervous system
  12. true or false:

    epinephrine and norepinephrine are not g protien second messenger receptors (slow response)

    they are g protien receptors, and slow
  13. alpha 1 and alpha 2 are located where?
    • alpha 1 is in smooth muscle of blood vessels of skin, kidney, gi tract and sphincters
    • decreases blood flow during sympathetic stimulation

    alpha 2 decrease activity of gi tract
  14. where are beta 1,2,3 receptors found?
    • B1- found in cardiac muscle, CNS, and kidneys increased force of contraction in cardiac muscle
    • B2- respiratory tract, uterus and some blood vessels, inhibitory response, relaxation of smooth muscle of vessels that supply heart and skeletal muscle. dilation of broncholes in lungs
    • B3-in lipolysis of adipose tissue, excitatory response mobilization of fats