Question 1

Which of the following best describes the function of the sarcoplasmic reticulum (SR) in skeletal muscle fibers?

Accepted Answer

It stores and releases calcium ions necessary for muscle contraction.

Question 2

A patient is diagnosed with Duchenne Muscular Dystrophy (DMD). Which protein is defective, and what is the consequence for muscle fibers?

Accepted Answer

Dystrophin; the sarcolemma breaks down and muscle fibers are replaced by connective tissue.

Question 3

During the sliding filament mechanism of muscle contraction, which of the following occurs?

Accepted Answer

The I band and H zone narrow, while the A band remains unchanged.

Question 4

Which of the following best explains why the resting membrane potential of a skeletal muscle fiber is negative?

Accepted Answer

More potassium ions diffuse out of the cell than sodium ions enter, making the inside more negative.

Question 5

A toxin blocks voltage-gated sodium channels in the sarcolemma. What is the most immediate effect on muscle contraction?

Accepted Answer

Action potentials cannot be generated, so muscle contraction will not occur.

Question 6

Which of the following events occurs first during the excitation phase at the neuromuscular junction?

Accepted Answer

An action potential arrives at the axon terminal of a motor neuron.

Question 7

What is the role of ATP in the crossbridge cycle during muscle contraction?

Accepted Answer

ATP binds to myosin, causing it to detach from actin after the power stroke.

Question 8

Which of the following best describes the difference between Type I and Type II muscle fibers?

Accepted Answer

Type I fibers have more mitochondria and myoglobin, making them more resistant to fatigue.

Question 9

A muscle is stretched to 150% of its optimal length before contraction. What is the expected effect on tension generation, and why?

Accepted Answer

Tension generation will decrease because there is less overlap between thick and thin filaments.

Question 10

Which of the following is a function unique to smooth muscle tissue compared to skeletal muscle tissue?

Accepted Answer

Regulating the diameter of hollow organs such as blood vessels.

Question 11

A patient receives an injection of botulinum toxin (Botox) in a facial muscle. What is the physiological effect at the neuromuscular junction?

Accepted Answer

Acetylcholine release is blocked, preventing muscle contraction.

Question 12

Which of the following best explains why creatine supplementation is only mildly effective for short bursts of muscle activity?

Accepted Answer

Creatine phosphate can rapidly regenerate ATP, but only for about 10 seconds of maximal activity.

Question 13

During which type of muscle contraction does the muscle length remain unchanged while tension is generated?

Accepted Answer

Isometric contraction

Question 14

Which of the following is the correct order of events during the excitation phase at the neuromuscular junction?

Accepted Answer

Action potential arrives at axon terminal → Acetylcholine is released → Acetylcholine binds to ligand-gated channels → Sodium enters muscle fiber → Local depolarization occurs

Question 15

Which of the following best describes the role of myoglobin in skeletal muscle fibers?

Accepted Answer

It binds and stores oxygen for use during aerobic metabolism.

Question 16

A muscle fiber is repeatedly stimulated at a frequency of 90 times per second, and tension remains nearly constant at maximum. What is this phenomenon called?

Accepted Answer

Fused (complete) tetanus

Question 17

Which of the following is true regarding the energy sources for muscle contraction?

Accepted Answer

Oxidative catabolism provides nearly 100% of the ATP required after several minutes of contraction.

Question 18

Which of the following best explains why smooth muscle can maintain contraction for long periods with minimal ATP consumption?

Accepted Answer

Smooth muscle can enter a latch state, maintaining tension in an energy-efficient manner.

Question 19

Which of the following is a property shared by all three types of muscle tissue?

Accepted Answer

The ability to generate force (muscle tension).

Question 20

A person is unable to maintain posture and experiences frequent falls. Which muscle fiber type is most likely deficient or dysfunctional?

Accepted Answer

Type I (slow-twitch) fibers

Muscle Tissue and Physiology: Structure, Function, and Mechanisms

스터디 가이드 - 연습 문제

학습 가이드 - 플래시카드