Question 1

Which property of muscle tissue allows it to respond to a chemical stimulus from a nerve cell with a change in membrane potential?

Accepted Answer

Excitability

Question 2

A muscle fiber is stimulated at a length where the zone of overlap between thick and thin filaments is minimal. What is the expected effect on tension production?

Accepted Answer

Tension production will be reduced because fewer cross-bridges can form.

Question 3

During a biceps curl, the flexion phase involves which type of muscle contraction?

Accepted Answer

Isotonic concentric contraction

Question 4

Which structure in skeletal muscle is responsible for storing and releasing calcium ions necessary for contraction?

Accepted Answer

Sarcoplasmic reticulum

Question 5

A patient presents with elevated creatine kinase (CK) levels in the blood. What does this most likely indicate?

Accepted Answer

Serious muscle damage

Question 6

Which protein prevents myosin from binding to actin in a resting skeletal muscle?

Accepted Answer

Troponin–tropomyosin complex

Question 7

What is the primary source of ATP for a muscle fiber during peak exertion when oxygen is limited?

Accepted Answer

Anaerobic glycolysis

Question 8

Which of the following best describes the sliding-filament theory of muscle contraction?

Accepted Answer

Thin filaments slide toward the center of the sarcomere alongside thick filaments.

Question 9

A muscle producing almost maximum tension during rapid cycles of contraction and relaxation is in which state?

Accepted Answer

Incomplete tetanus

Question 10

Which of the following equations correctly represents the reaction catalyzed by creatine kinase during muscle contraction?

Accepted Answer

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

Question 11

Which structural feature distinguishes cardiac muscle cells from skeletal muscle fibers?

Accepted Answer

Cardiac muscle cells are branched and typically have a single, centrally placed nucleus.

Question 12

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

Accepted Answer

Pumping blood through the cardiovascular system

Question 13

During muscle contraction, which event occurs during the contraction phase of a twitch?

Accepted Answer

Calcium ions bind to troponin, exposing active sites on thin filaments.

Question 14

Which process describes the smooth but steady increase in muscular tension produced by increasing the number of active motor units?

Accepted Answer

Recruitment

Question 15

A muscle is fixed at both ends and stimulated with a load greater than its maximum tension. Which type of contraction occurs?

Accepted Answer

Isometric contraction

Question 16

Which mechanism is primarily responsible for returning a muscle to its resting length after contraction?

Accepted Answer

Elastic forces, opposing muscle contractions, and gravity

Question 17

Which of the following statements about cardiac muscle tissue is TRUE?

Accepted Answer

Cardiac muscle cells contract automatically without neural stimulation.

Question 18

Which equation best represents the net ATP yield from glycolysis of one glucose molecule?

Accepted Answer

$$ \mathrm{glucose} \rightarrow 2\ \mathrm{pyruvate} + 2\ \mathrm{ATP} $$

Question 19

Which of the following best explains why cardiac muscle cannot undergo wave summation or tetanic contractions?

Accepted Answer

Cardiac muscle cells require both intracellular and extracellular calcium ions, making them more sensitive to changes in calcium concentration.

Question 20

A cyclist is climbing a hill and notices that their leg muscles contract more slowly as the load increases. Which principle explains this phenomenon?

Accepted Answer

The speed of contraction is inversely related to the load.

Ch 10: Muscle Tissue: Structure, Function, and Physiology

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