Describe and compare the action potentials from cardiac ventricular muscle and the sinoatrial node.
This topic was well understood and answered by most candidates. Some candidates had a
good knowledge base but missed out on potential marks by failing to compare and contrast. A
diagram outlining the various phases was a useful way to approach the question.
A "diagram outlining various phases" would probably look something like this:
However, for a "compare & contrast" SAQ, the best way to earn marks is with a tabulated answer:
Cell | Ventricular Myocyte | Pacemaker cell |
Resting potential | -90 mV | -60 mV |
Threshold Potential | -70 mV | - 40 mV |
Phase 4 |
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Phase 0 |
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Phase 1 |
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Phase 2 |
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Phase 3 |
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Bers, Donald M. "Cardiac excitation–contraction coupling." Nature 415.6868 (2002): 198-205.
Draper, Morrell Henry, and Silvio Weidmann. "Cardiac resting and action potentials recorded with an intracellular electrode." The Journal of physiology 115.1 (1951): 74-94.
Bers, Donald M. "Cardiac excitation–contraction coupling." Nature 415.6868 (2002): 198-205.
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