After a skeletal muscle fiber is treated with a membrane permeable drug that speeds up the action of the SR Ca 2-ATPase, how would contraction differ after multiple and frequent action potentials

the twitch would be shorter

Explanation:

In muscle cells, the calcium (Ca2+) pump ATPase membrane transport proteins maintain a low cytosolic Ca2+ concentration in order to promote muscle contraction. Muscle relaxation occurs when the sarcoplasmic reticulum reabsorbs Ca2+ through the Ca2+-ATPase protein, thereby reducing intramuscular Ca2+ levels. In muscle contraction, intracellular Ca2+ levels are raised due to the release of Ca2+ from the sarcoplasmic reticulum (SR) via Ca2+-release channels. In consequence, it is expected that a specific drug that speeds up the action of (Ca2+) pump ATPase protein should shorten the contraction-relaxation cycle by increasing the velocity of muscle relaxation.

answer:   option a) glucagon was secreted by his pancreas before he ate the cookies because blood glucose was low. insulin was secreted after he ate the cookies because his blood glucose was high.

explanation: