Relative to skeletal muscle, smooth muscle

Relative to skeletal muscle, smooth muscle

A) only uses less energy to generate a given amount of force.
B) only can sustain contractile force without fatigue.
C) only uses calcium from the sarcoplasmic reticulum and extracellular space.
D) uses less energy to generate a given amount of force and can sustain contractile force without fatigue.
E) uses less energy to generate a given amount of force, can sustain contractile force without fatigue and uses calcium from the sarcoplasmic reticulum and extracellular space.


Answer: : E

An important difference between single-unit and multiunit smooth muscle is the

An important difference between single-unit and multiunit smooth muscle is the

A) numerous gap junctions in single-unit smooth muscle, which allow many cells to work together as a sheet.
B) longer actin and myosin filaments in multiunit smooth muscle, which allow coordination of contraction.
C) ability of single-unit fibers to change into multiunit fibers when advantageous.
D) closely controlled individual fibers in single-unit smooth muscle to allow fine control and graded contractions by selective activation.



Answer: : A

Put these myofibers in the order they would be recruited as the body moves from a weak to a strong stimulus:

Put these myofibers in the order they would be recruited as the body moves from a weak to a strong stimulus:

1. glycolytic fast-twitch fibers
2. fatigue-resistant oxidative fast-twitch fibers
3. fatigue-resistant slow-twitch fibers



A) 1, 2, 3
B) 2, 3, 1
C) 3, 2, 1
D) 1, 3, 2
E) 3, 1, 2


Answer: : C

The force generated by a single muscle fiber can be increased by

The force generated by a single muscle fiber can be increased by

A) increasing frequency of action potentials only.
B) increasing muscle length beyond optimal only.
C) increasing the asynchrony of recruitment only.
D) increasing frequency of action potentials and increasing muscle length beyond optimal only.


Answer: : A

Skeletal muscle fibers with the greatest endurance rely on ________ for energy.

Skeletal muscle fibers with the greatest endurance rely on ________ for energy.

A) anaerobic glycolysis
B) oxidative phosphorylation
C) lactic acid accumulation
D) ketone body degradation


Answer: : B

The factor(s) that determine the duration of a twitch in various types of fibers is the speed of the

The factor(s) that determine the duration of a twitch in various types of fibers is the speed of the

A) removal of Ca2+ ions from the sarcoplasm only.
B) hydrolysis of ATP only.
C) movement of Na+ across their membranes only.
D) removal of Ca2+ ions from the sarcoplasm and hydrolysis of ATP.
E) removal of Ca2+ ions from the sarcoplasm and hydrolysis of ATP and movement of Na+ across their membranes.


Answer: : A