Section X: Special Topics (B)

Section X – Special Topics (B)

Select the one of the following that is NOT CORRECT:

A. The troponin system regulates contraction of smooth muscle.

B. Muscle contraction takes place via a sliding filament mechanism.

C. Myosin light-chain kinase phosphorylates the regulatory light chains in the myosin head domain.

D. F-actin is formed via the polymerization of G-actin.

E. Ca²⁺ both activates muscle contraction and stimulates its own removal by activating the Ca²⁺ ATPase.

A patient anesthetized using a halothane compound exhibits a marked rise in body temperature, a behavior indicative of malignant hyperthermia (HT). Select the one of the following statements that is NOT CORRECT:

A. MH can arise from mutations that alter the amino acid sequence of the Na⁺-K⁺-ATPase.

B. MH can arise from mutations that alter the amino acid sequence of the ryanodine-sensitive Ca²⁺ release channel.

C. The muscle rigidity that occurs during MH is triggered by the presence of high concentrations of Ca²⁺ in the cytoplasm.

D. MH can arise from mutations that alter the amino acid sequence of the voltage-gated, slow K-type Ca²⁺ channel.

E. MH can be treated by intravenous administration of dantrolene, which inhibits release of Ca²⁺ from the sarcoplasmic reticulum into the cytosol.

Select the one of the following statements that is NOT CORRECT:

A. Fast-twitch fibers rely heavily on creatine phosphate to regenerate ATP.

B. Slow-twitch fibers appear red because they contain hemoglobin.

C. Fast-twitch fibers contain relatively few mitochondria.

D. Marathoners try to increase the quantity of glycogen in their muscles by eating carbohydrate-rich meals before an event (carbo loading).

E. Skeletal muscle serves as the major reserve of protein in the body.

Select the one of the following that is NOT a feature of the contractile cycle in striated muscle:

A. Binding of Ca²⁺ to troponin C uncovers the myosin-binding sites on actin.

B. The power stroke is initiated by the release of P_i from the actin-myosin-ADP-P_i complex.

C. Release of ADP from the actin-myosin-ADP complex ...