Muscle cramps are followed by muscle weakness. Explain how changes in membrane p
ID: 3472389 • Letter: M
Question
Muscle cramps are followed by muscle weakness. Explain how changes in membrane potential and ion flux cause subsequent skeletal muscle weakness. Inhibited repolarization and over-stimulation leads to muscle fibers becoming less excitable; longer refractory period; sodium channels inactive for longer.
The most serious effect of hyperkalemia is cardiac arrest. Is it likely that the heart will stop beating during a heartbeat (while the cardiac muscle is stimulated to contract) or in between beats? Why?
Explanation / Answer
1. Well the changes in the memmbrane potential and ion influx can cause subsequent skelatal muscle to become weak due to a condition called as hyperkelemia which causes the membrane potential less negative due to the outward movent of the sodium ions leading to depolarization. at this moment the cell becomes unable to repolarize which can make the cell less excitable and the cell will undergo a longer refractory period, and the sodium channels get inactivated for a longer duration.
2. Yes, the heart can stop beating in between the beats because during hyperkelemia the cells become less excitable because they have undergone a longer refractory period. this generally occurs during the diastole because this is the period when the cardiac cells relax and they become less excitable as they can't be repolarized.
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