NUR MSK Set 1

The fundamental repeating unit of the myofibril called a ________ gives skeletal muscle its

striated appearance, and is bordered by ________.

• crossbridge : Z lines

• sarcomere : M lines

• sarcomere : I bands

• sarcomere : Z lines

The contractile portion of the thin filament is composed of what protein?

• myosin

• tropomyosin

• troponin

• actin

What is the protein component of the thin filament that binds to calcium thereby initiating

skeletal muscle contraction?

• myosin

• tropomyosin

• troponin

• actin

The shortening of a skeletal muscle fiber during contraction involves which of the following?

• the thick filaments shortening

• the thin filaments shortening

• the sarcomeres shortening

• the A bands shortening

During skeletal muscle contraction, as the muscle shortens, the thick and thin filaments

________.

• shorten

• slide past one another

• do not interact

• lengthen

When a skeletal muscle is passively stretched, that cell has a tendency to spring back once the

force that was stretching the muscle is removed due to ________.

• the passive interaction between actin and myosin (no energy required)

• titin acting as a spring using the energy stored by the stretching

• actin and myosin acting as a spring using the energy stored by the stretching

• the elastic connective tissue that surrounds the muscle cells and fascicles

The repeated, oscillating interaction between actin and myosin that results in the generation of

force by a skeletal muscle cell is called what?

• crossbridge cycling

• the sliding-filament model

• Z line interaction

• sarcomeric facilitation

What converts the myosin head into the high-energy state?

• binding to ATP only

• binding to actin

• the hydrolysis of ATP

• binding to titin

The release of an inorganic phosphate from the myosin molecule directly results in which of

the following?

• development of rigor

• power stroke

• cocking of the myosin head

• binding of actin to myosin

In order for crossbridge cycling to occur, the actin-myosin complex must be broken by which

of the following?

• binding of tropomyosin to myosin

• binding of ATP to actin

• binding of the troponin complex to actin

• binding of ATP to myosin