Question

Which off the following does NOT occur during skeletal muscle contraction?

Titin fibers compress

Actin and myosin shorten

Sarcomers shorten

2. Action potential propagated along the sarcolemma stimulate ___________ located on transverse tubules.2.

Nicotinic receptors

Ryanodine receptors

DHP receptors

3. Which of the following does not occur during the "Excitation" of a skeletal muscle?

Group of answer choices

The cell membrane depolarizes

ATPase on myosin heads split ATP

The myosin head binding site on actin is exposed

The passive force of contraction increases

4. What happens as an IMMEDIATE result of Ryanodine receptors on the sarcoplasmic reticulum being stimulate?

Ryanodine receptors simulate DHP receptors on T-tubules

Myosin cross bridges are formed

Calcium ions diffuse out of the saroplasmic reticulum

5. Why does lactic acid produced during anaerobic metabolism cause fatigue?

Because H+ from lactic acid interfers with crossbridge formation

Because lactic acid produced duirng anaerobic metabolism produces only 2 molecules of ATP

Because the myosin head is denature by lactic aci

Answer 1

1. Actin and myosin shorten

Sarcomere shortens but actin and myosin do not shorten bu tslide past each other in muscle contraction.

2. DHP receptors

The influx of extracellular Ca2+ in cardiac muscle takes place either through the dihydropyridine receptors (DHPRs), L-type voltage sensitive Ca2+ channels, located in plasmalemma and T-tubules.

While, ryanodine receptors are located in the sarcoplasmic/endoplasmic reticulum membrane and are responsible for the release of calcium from intracellular stores during excitation-contraction coupling in both cardiac and skeletal muscle

3.The passive force of contraction increases

Passive forces involves structures inside the muscle fiber that elongate elastically when they are pulled apart. Active force of contraction increases in excitation of skeletal muscles.

4.Calcium ions diffuse out of the saroplasmic reticulum

Ryanodine receptors mediate the release of calcium ions from the sarcoplasmic reticulum and endoplasmic reticulum during muscle contraction.

5.Because lactic acid produced duirng anaerobic metabolism produces only 2 molecules of ATP

Hydrogen from lactic acid reduces the pH which can cause muscle fatigue