Question

Why do the different skeletal muscle fiber types vary in the speed and duration of their twitches?

Answer 1

Answer:

The different skeletal muscle fiber types vary in the speed and duration of their twitches due to -

b) They vary in the rate of hydrolysis of ATP

c) They vary in the removal of Ca+ from the cytosol

Explanation:

There are mainly two types of muscle fibers , i.e.

a) slow twitching, long contraction duration( type I fibers)

b) First twitching but short duration of contraction. ( type II fibers).

Now think of the physiology of muscle. Two components are important, cytosolic Ca++ concentration and Availability of ATP. K+ is related to the action potential ( none or all law, there is no relation to the duration with respect to the potassium). For long contraction muscle fibers need a more steady supply of ATP, and also consistent high concentration of cytosolic Ca++ for muscle contraction to happen. So, these two factor is important for the duration of twitching. So the answer is option f .