Question

Briefly, describe the functions of these 5 structures.

(a) transverse tubule

(b) perimysium

(c) satellite cells

(d) sarcoplasmic reticulum

(e) myosin ATPase

Now, hypothesize what would happen to skeletal muscle function if the number of RyR were reduced by 50%

Answer 1

a. T-tubules or transverse tubules are narrow tubules formed by the Invagination of the sarcolemma. These tubules penetrate all the way from one side of the muscle fiber to another side. That is, these tubules penetrate the muscle cell through and through.

b. In the muscle, the muscle fibers are arranged in various groups called bundles or fasciculi. Connective tissue sheath that covers each fasciculus is called perimysium

c. Satellite cells are the glial cells present on the exterior surface of PNS neurons. Its function is to

i. Provide physical support to the PNS neurons

ii. Help in the regulation of the chemical environment of ECF around the PNS neurons.

d. Sarcoplasmic reticulum is endoplasmic reticulum of muscle fibers, it stores the calcium ions, required for contraction of a muscle. The sarcoplasmic reticulum complex includes L tubules and T tubules. L tubules or longitudinal tubules are the closed tubules that run in the long axis of the muscle fiber, forming sarcoplasmic reticulum.

e. Myosin head bears a site known as myosin ATPase. It is the site where ATP breaks to release energy and inorganic Phosphate. The energy released is used for the movement of cross arm and detachment of actin and myosin.

Now if the numbers of RyR are reduced to half then the secretion of calcium also reduced to half this cause half the number of removal of troponin from tropomyosin and results into lesser power of contraction.