Question 1

Which of the following best describes the difference between isotonic and isometric muscle contractions?

Accepted Answer

Isotonic contractions involve muscle shortening or lengthening with movement of the load, while isometric contractions generate tension without changing muscle length.

Question 2

A patient is performing a bicep curl. During the upward phase, which type of contraction is primarily occurring in the biceps brachii?

Accepted Answer

Concentric isotonic contraction

Question 3

Which of the following mechanisms is responsible for the graded strength of skeletal muscle contractions?

Accepted Answer

Changing the frequency and strength of stimulation

Question 4

A muscle fiber is stimulated repeatedly at a high frequency, resulting in a sustained contraction without relaxation. What is this phenomenon called?

Accepted Answer

Fused tetanus

Question 5

Which equation correctly represents the direct phosphorylation of ADP by creatine phosphate in muscle cells?

Accepted Answer

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

Question 6

Which of the following best explains why muscle fatigue occurs during prolonged, intense exercise?

Accepted Answer

Accumulation of inorganic phosphate and ionic imbalances disrupt excitation-contraction coupling.

Question 7

During recovery from strenuous exercise, which process is NOT part of excess post-exercise oxygen consumption (EPOC)?

Accepted Answer

Increasing the number of motor units in the muscle

Question 8

A muscle fiber at less than 80% of its resting sarcomere length will produce less force because:

Accepted Answer

The filaments overlap too much, reducing the number of effective cross-bridges.

Question 9

Which type of muscle fiber is most resistant to fatigue and best suited for endurance activities?

Accepted Answer

Slow oxidative fibers

Question 10

Which of the following statements about smooth muscle is TRUE?

Accepted Answer

Smooth muscle contraction is slow, sustained, and fatigue-resistant.

Question 11

Which protein replaces troponin in smooth muscle to bind calcium and initiate contraction?

Accepted Answer

Calmodulin

Question 12

Which of the following best describes the role of gap junctions in single-unit smooth muscle?

Accepted Answer

They allow for rapid, synchronized contraction by transmitting action potentials between adjacent cells.

Question 13

A patient with a genetic mutation affecting myosin ATPase activity in skeletal muscle would most likely experience which symptom?

Accepted Answer

Decreased speed of muscle contraction

Question 14

Which of the following is a feature unique to multi-unit smooth muscle compared to single-unit smooth muscle?

Accepted Answer

Each muscle fiber is structurally independent and forms its own motor unit

Question 15

Which metabolic pathway is primarily used by fast glycolytic muscle fibers for ATP synthesis during short, intense activities?

Accepted Answer

Anaerobic glycolysis

Question 16

If a muscle is stretched to more than 120% of its resting sarcomere length, what happens to its ability to generate force?

Accepted Answer

Force decreases because filaments do not overlap enough for cross-bridge formation.

Question 17

Which of the following is NOT a function of ATP in muscle contraction?

Accepted Answer

Storing oxygen for aerobic respiration

Question 18

Which of the following best explains the stress-relaxation response in smooth muscle?

Accepted Answer

Smooth muscle responds to stretch by contracting briefly, then adapting to the new length and relaxing.

Question 19

Which of the following statements about muscle fiber types is correct?

Accepted Answer

Genetics determine the percentage of each fiber type in an individual.

Question 20

During light-to-moderate exercise, which energy system is primarily used by skeletal muscle?

Accepted Answer

Aerobic respiration

Contractile Properties of Skeletal and Smooth Muscles: Anatomy & Physiology I Study Notes

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