Stauber Cardiac Muscle
Terms
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EPP/ MAP
Time coure
Refractoriness
Response
Conductance -
longer/ shorter
None. (no ion-gated channel)/ Absolute, relative
local, graded, non-propagated/ All or none, propagated
simultaneous, Na and K, ACh dependent./ sequential, ion specific, voltage dependent<
- Cardiac potential during triggered release.
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30 mV. (EPP)
More ACh-Receptor complexes = more conductance change.
EPP potential large enough for MAP.
- Cardiac membrane potential at rest.
- -75 mV.
- Post synaptic; NJM
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pg 6-7
- Tell me about the safety margin. (# of vesicles and calcium removal)
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-No. of vesicles related to No. of releasable vesicles and Probability of interation.
-There's a slight delay (1-2 msec) for vesicles to interact w/ membrane.
-Ca removal = stop neurotransmitter release during repolarization of nerve. - What are some special properties of NMJ?
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-Unidirectional transmission
-Sensitive to poisons and drugs
-Signal delay.
-EPP. Non-propagated membrane depolarization.
Results in response to ACh release.
-Amplification. Small - What constitues the prejunctional events?
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Transmitter synthesis - ACh from Acetyl-CoA and choline by chohline acetyylase (present in nerve ending).
Packaging - ACh transported from site of synth. to vesicles. Proton driven excha - What happens in the synaptic cleft?
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Diffusion of transmitter - Diffuse; interact w/ receptor; degraded
-2 ACh per 1 receptor
Inactivation of transmitter - Diffuse away. OR AChE hydrolyzes into acetate and choline. - What kinds of transmitter release is there?
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Spontaneous - Non-coupled. MEPP (small voltage change). Release of vesicle contents to synaptic cleft.
Triggered - Calcium entry. Large conductance change.
- What's myasthenia gravis?
- Antibodies bind to ACh receptors and block interaction; they don't cause activity.
- What's Post-tetanic facilitation?
- From accumulation of excess calcium vs. when it started. More Ca inside = more vesicles fuse during nerve AP = amplified response.
- What's the anatomy of the NMJ?
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Nerve ending - Membrane of presynaptic ending is thickened. Attachment (docking) proteins for vesicles to fuse for exocytosis.
Post-synaptic - Membrane thicker. Receptor proteins for chemical transmitter. They