Question 1

Which of the following best describes the primary 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

What is the main function of the sarcoplasmic reticulum in skeletal muscle fibers?

Accepted Answer

It stores and releases calcium ions ($$Ca^{2+}) $$necessary for muscle contraction.

Question 3

During the cross-bridge cycle in skeletal muscle contraction, what event directly follows the power stroke?

Accepted Answer

ATP binds to myosin, causing myosin to detach from actin.

Question 4

Which protein makes up the thick filament in a sarcomere, and what is its primary function?

Accepted Answer

Myosin; generates force for muscle contraction by binding to actin.

Question 5

A patient is experiencing muscle weakness due to a defect in the neuromuscular junction. Which step is most likely impaired?

Accepted Answer

Release of acetylcholine from the synaptic knob.

Question 6

Which equation correctly represents the process of ATP hydrolysis during muscle contraction?

Accepted Answer

$$ATP + H_2O \rightarrow ADP + P_i + energy$$

Question 7

What is the physiological significance of the refractory period in skeletal muscle fibers?

Accepted Answer

It ensures that each action potential is followed by a period during which the muscle fiber cannot be re-excited, allowing proper timing of contractions.

Question 8

Which of the following best explains why oxidative fibers are more resistant to fatigue than glycolytic fibers?

Accepted Answer

Oxidative fibers contain more mitochondria and rely on aerobic respiration, which produces more ATP per glucose molecule.

Question 9

A marathon runner’s skeletal muscles adapt to endurance exercise by increasing which of the following?

Accepted Answer

Number of mitochondria and capillary density.

Question 10

Which of the following is TRUE regarding the length-tension relationship in skeletal muscle?

Accepted Answer

Maximum tension is produced when there is optimal overlap between actin and myosin filaments.

Question 11

Which process is more beneficial for sustained muscle contraction and why: glycolysis or aerobic respiration?

Accepted Answer

Aerobic respiration, because it produces more ATP per glucose molecule and supports longer duration activities.

Question 12

What is the role of calcium ions ($$Ca^{2+}) in $$the excitation-contraction coupling of skeletal muscle?

Accepted Answer

They bind to troponin, causing a conformational change that exposes myosin binding sites on actin.

Question 13

A muscle twitch consists of which three phases, in correct order?

Accepted Answer

Latent, contraction, relaxation.

Question 14

Which of the following best describes the sliding filament theory?

Accepted Answer

Myosin filaments slide past actin filaments, causing the sarcomere to shorten.

Question 15

Which of the following is a direct result of acetylcholine binding to receptors on the motor end plate?

Accepted Answer

Generation of an action potential in the muscle fiber membrane.

Question 16

Which equation best represents the process of creatine phosphate donating a phosphate to ADP?

Accepted Answer

$$Creatine\ phosphate + ADP \rightarrow Creatine + ATP$$

Question 17

Which of the following is a benefit of multi-unit smooth muscle arrangement?

Accepted Answer

It allows for fine control and independent contraction of individual muscle fibers.

Question 18

What happens to skeletal muscle in response to disuse (such as immobilization in a cast)?

Accepted Answer

Muscle fibers undergo atrophy, decreasing in size and strength.

Question 19

Which of the following is TRUE about the mechanism of smooth muscle contraction?

Accepted Answer

Calcium binds to calmodulin, activating myosin light-chain kinase.

Question 20

Excess postexercise oxygen consumption (EPOC) is required for which of the following reasons?

Accepted Answer

To replenish ATP and creatine phosphate stores, remove lactic acid, and restore oxygen levels in myoglobin.

Muscle Tissue: Structure, Function, and Physiology

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