Question 1

Which of the following best describes the primary function of the sarcoplasmic reticulum in skeletal muscle cells?

Accepted Answer

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

Question 2

During the sliding filament theory of muscle contraction, which event directly requires ATP?

Accepted Answer

The detachment of the myosin head from actin after the power stroke.

Question 3

A patient is exposed to a toxin that inhibits acetylcholinesterase at the neuromuscular junction. What is the most likely effect on muscle contraction?

Accepted Answer

Muscle contraction will be prolonged due to continuous stimulation by acetylcholine.

Question 4

Which of the following best explains why rigor mortis occurs after death?

Accepted Answer

ATP is no longer produced, so myosin heads cannot detach from actin.

Question 5

Which ion is primarily responsible for the depolarization phase of an action potential in a muscle cell?

Accepted Answer

Sodium ($$\mathrm{Na^+})$$

Question 6

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

Accepted Answer

Tetanus

Question 7

Which of the following best describes the difference between fast-twitch and slow-twitch muscle fibers?

Accepted Answer

Slow-twitch fibers rely primarily on aerobic metabolism, while fast-twitch fibers fatigue quickly.

Question 8

During muscle contraction, what is the role of ATP in calcium ion ($$\mathrm{Ca$$^{2+}$$}) $$regulation?

Accepted Answer

ATP is used to pump $$\mathrm{Ca$$^{2+}$$}$$ back into the sarcoplasmic reticulum after contraction.

Question 9

Which of the following best explains why the length-tension relationship is important in muscle physiology?

Accepted Answer

It describes the optimal overlap of actin and myosin filaments for maximal tension.

Question 10

A muscle cell is in the absolute refractory period. Which of the following is true?

Accepted Answer

It cannot generate another action potential regardless of stimulus strength.

Question 11

Which of the following is NOT a major source of ATP for muscle contraction during the first 30 seconds of intense exercise?

Accepted Answer

Aerobic metabolism

Question 12

Which of the following best describes the arrangement of muscle fascicles in a pennate muscle?

Accepted Answer

Fascicles are short and attach obliquely to a central tendon.

Question 13

Which of the following best explains the function of the Na$$^+/K$^+$$ pump in muscle cells?

Accepted Answer

It restores the resting membrane potential by moving Na$$^+$$ out and K$$^+ in$$, using ATP.

Question 14

Which of the following is a correct sequence of events in excitation-contraction coupling in skeletal muscle?

Accepted Answer

Acetylcholine release → Action potential → Ca$$^{2+}$$ release → Cross-bridge formation

Question 15

Which of the following best describes the role of troponin in muscle contraction?

Accepted Answer

Troponin binds Ca$$^{2+}$$, causing a conformational change that moves tropomyosin and exposes myosin binding sites on actin.

Question 16

Which of the following is a characteristic of smooth muscle but NOT skeletal muscle?

Accepted Answer

It lacks sarcomeres.

Question 17

A muscle is named 'biceps femoris.' Based on anatomical naming conventions, what does 'biceps' indicate?

Accepted Answer

The muscle has two origins.

Question 18

Which of the following best explains why increasing the number of active motor units in a muscle increases tension?

Accepted Answer

More motor units means more muscle fibers are contracting simultaneously.

Question 19

During an action potential, which event occurs immediately after sodium channels close?

Accepted Answer

Potassium channels open, allowing K$$^+ to $$exit the cell.

Skeletal Muscle Anatomy & Physiology: Study Guide

스터디 가이드 - 연습 문제

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