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10 10 10 10 10 - guest1
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05-27-2008, 09:58 PM
The flow of calcium into the cell is an important component of the
upstroke phase of action potentials in a. Cardiac ventricular muscle b. Intestinal smooth muscle c. Skeletal muscle fibers d. Nerve cell bodies e. Presynaptic nerve terminals
05-27-2008, 10:02 PM
cardiac ventricular muscle - think Na instead of Ca....one more try killmle.... A is not correct.
05-27-2008, 10:05 PM
ok, i say you're 50% correct mydad....now choose 1 out of 2.
05-27-2008, 10:09 PM
B is correct. In intestinal smooth muscle,
the upstroke of the action potential is caused by the flow of calcium into the cell. In cells of the cardiac ventricular muscle, the plateau phase of the action potential, but not the upstroke, is accompanied by the flow of calcium into the cells. Skeletal muscle fibers resemble nerve fibers. In both of these cells, the upstroke of the action potential is caused by the flow of sodium into the cell.
05-27-2008, 10:12 PM
[edit] Neurotransmitter release
The release of a neurotransmitter is triggered by the arrival of a nerve impulse (or action potential) and occurs through an unusually rapid process of cellular secretion, also known as exocytosis: Within the presynaptic nerve terminal, vesicles containing neurotransmitter sit "docked" and ready at the synaptic membrane. The arriving action potential produces an influx of calcium ions through voltage-dependent, calcium-selective ion channels at the down stroke of the action potential (tail current).[2] Calcium ions then trigger a biochemical cascade which results in vesicles fusing with the presynaptic membrane and releasing their contents to the synaptic cleft within 180µsec of calcium entry.[2] Vesicle fusion is driven by the action of a set of proteins in the presynaptic terminal known as SNAREs. The membrane added by this fusion is later retrieved by endocytosis and recycled for the formation of fresh neurotransmitter-filled vesicles. what do u think abt this |
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