The myocardial action potential has five phases, each of which is characterized by the activity of a different ion channel.
Calcium influx into the cytoplasm from the
sarcoplasmic reticulum causes contraction of the myocyte. Removal of calcium from the cytoplasm when contraction is no longer desired, such as during myocardial diastole, is critical to restoring low basal calcium concentration.
The Na+-Ca2+ exchanger helps to re-establish the baseline resting potential which is the key step in the final phase, Phase 4. of the myocardial AP. At this point, the myocyte has now reached its baseline resting potential again and awaits the next AP.
vs.
The ryanodine receptor (Choice E) is located on the sarcoplasmic reticulum and allows theThis efflux of Ca2+ into the cytoplasm, initiating excitation-contraction coupling. However, this receptor is not responsible for the reuptake of Ca2+ into the SR or re-establishment of resting potential!!
submitted by โnamesthegame22(13)
The myocardial action potential has five phases, each of which is characterized by the activity of a different ion channel.
Calcium influx into the cytoplasm from the sarcoplasmic reticulum causes contraction of the myocyte. Removal of calcium from the cytoplasm when contraction is no longer desired, such as during myocardial diastole, is critical to restoring low basal calcium concentration.
The Na+-Ca2+ exchanger helps to re-establish the baseline resting potential which is the key step in the final phase, Phase 4. of the myocardial AP. At this point, the myocyte has now reached its baseline resting potential again and awaits the next AP.
vs.
The ryanodine receptor (Choice E) is located on the sarcoplasmic reticulum and allows theThis efflux of Ca2+ into the cytoplasm, initiating excitation-contraction coupling. However, this receptor is not responsible for the reuptake of Ca2+ into the SR or re-establishment of resting potential!!