Question 1

Which of the following best describes the main difference between skeletal, cardiac, and smooth muscle tissue?

Accepted Answer

Skeletal muscle is striated and voluntary, cardiac muscle is striated and involuntary, and smooth muscle is non-striated and involuntary.

Question 2

Which connective tissue sheath surrounds individual muscle fibers?

Accepted Answer

Endomysium

Question 3

During the sliding filament model of contraction, what happens to the sarcomere?

Accepted Answer

The Z discs move closer together, and the I bands shorten.

Question 4

Which protein binds calcium ions to initiate skeletal muscle contraction?

Accepted Answer

Troponin

Question 5

A patient is diagnosed with Duchenne muscular dystrophy. Which of the following best explains the molecular defect in this disease?

Accepted Answer

A defective gene for dystrophin, leading to unstable sarcolemma and muscle fiber damage.

Question 6

Which of the following events occurs first during excitation-contraction coupling in skeletal muscle?

Accepted Answer

Action potential travels down the T tubules.

Question 7

Which of the following best describes the role of the Na+-K+ pump during muscle fiber repolarization?

Accepted Answer

It restores ionic conditions by pumping Na+ out and K+ into the cell after an action potential.

Question 8

Which of the following is true regarding the energy systems used during muscle contraction?

Accepted Answer

Direct phosphorylation of ADP by creatine phosphate provides energy for about 15 seconds.

Question 9

A muscle is contracting but not shortening because the load is greater than the tension the muscle can generate. What type of contraction is this?

Accepted Answer

Isometric contraction

Question 10

Which of the following best explains why smooth muscle can maintain contraction for long periods with little energy cost?

Accepted Answer

Smooth muscle myofilaments may latch together, and ATPases are slower.

Question 11

Which of the following is a correct sequence of events in the cross-bridge cycle?

Accepted Answer

Cross bridge formation, power stroke, cross bridge detachment, cocking of myosin head

Question 12

Which of the following best describes the 'size principle' of motor unit recruitment?

Accepted Answer

Motor units with the smallest muscle fibers are recruited first, followed by larger units as stimulus intensity increases.

Question 13

Which of the following is a unique feature of cardiac muscle tissue compared to skeletal muscle?

Accepted Answer

Presence of intercalated discs for electrical coupling.

Question 14

Which of the following is the correct equation for the direct phosphorylation of ADP by creatine phosphate?

Accepted Answer

$$\mathrm{Creatine\ phosphate + ADP \rightarrow Creatine + ATP}$$

Question 15

Which of the following best explains the effect of sarcomere length on force generation?

Accepted Answer

Force generation is greatest when sarcomeres are at 80–120% of their normal resting length.

Question 16

Which of the following is a characteristic of multiunit smooth muscle?

Accepted Answer

It has few gap junctions and is controlled by the autonomic nervous system and hormones.

Question 17

Which of the following best describes the mechanism by which calcium initiates contraction in smooth muscle?

Accepted Answer

Calcium binds to calmodulin, which activates myosin light chain kinase.

Question 18

Which of the following is NOT a function of muscle tissue?

Accepted Answer

Synthesizing hormones

Question 19

A patient experiences muscle rigidity after death (rigor mortis). What is the primary reason for this phenomenon?

Accepted Answer

Lack of ATP prevents detachment of myosin heads from actin.

Muscle Tissue: Structure, Function, and Physiology

Study Guide - Practice Questions