12 pts - If a heart is removed from the body, its beat rate actually speeds...

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Biology

12 pts - If a heart is removed fromthe body, its beat rate actually speeds up until sugar reservesdwindle.Â Â
Discuss how the SA [sinoatrial-pacemaker] node cells manipulateions at their surface to rhythmically contract.Â Â Bespecific about pumps, transporters, and channels.Â Â Makesure your explanation includes setup and recovery back to set-up.Be specific about how the Action Potential passes down the lengthof the cardiac cell and from one cell to the next.
Then discuss how the bodyâ€™s parasympathetic nervous systemslows this rate down to a more normal ~65 beats/minute [if theheart is still â€œhooked upâ€].Â Â Be clear about all theroles for the various channels, pumps, receptors and allostericsecondary messengers in both normal contraction and slowedcontraction. How is the above story manipulated?
How does the sympathetic system do the opposite and speed theheart up?

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3.5 Ratings (588 Votes)

The action potential initiated by the SA node travels along theconduction system and spreads out to excite the working atrialand ventricular muscle fibers called contractile fibers There arefollowing steps which take place during action potentialDepolarization Unlike autorhythmic fiberscontractile fibers have a stable resting membrane potential that isclose to 90 mV When a contractile fiber is brought to threshold byan action potential from neighboring fibers its voltagegated fastNa channels open These sodium ion channels are referred to asfast because they open very rapidly in response to athresholdlevel depolarization Opening of these channels allows Nain flow because the cytosol of contractile fibers is electricallymore negative than See Answer

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