Question 1

Which connective tissue layer surrounds individual muscle fibers within a skeletal muscle?

Accepted Answer

Endomysium

Question 2

What is the functional unit of skeletal muscle contraction?

Accepted Answer

Sarcomere

Question 3

During muscle contraction, which band remains the same width while the others shorten?

Accepted Answer

A band

Question 4

Which protein anchors thick filaments in the sarcomere and is the largest known protein in the human body?

Accepted Answer

Titin

Question 5

What is the role of troponin in skeletal muscle contraction?

Accepted Answer

It binds calcium and moves tropomyosin to expose myosin-binding sites on actin.

Question 6

Which event directly triggers the release of calcium from the sarcoplasmic reticulum during excitation-contraction coupling?

Accepted Answer

Activation of dihydropyridine receptors by an action potential

Question 7

What is the primary function of the transverse (T) tubules in skeletal muscle fibers?

Accepted Answer

To transmit action potentials deep into the muscle fiber

Question 8

Which of the following best describes the sliding filament mechanism of muscle contraction?

Accepted Answer

Thin filaments slide past thick filaments, shortening the sarcomere

Question 9

What is the correct sequence of events in the cross-bridge cycle?

Accepted Answer

Binding, power stroke, detachment, re-energizing

Question 10

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

Accepted Answer

$$\mathrm{ATP} \rightarrow \mathrm{ADP} + \mathrm{P_i}$$

Question 11

A patient with a genetic mutation in the titin protein would most likely experience which of the following symptoms?

Accepted Answer

Reduced elasticity and stability of muscle fibers

Question 12

Which of the following statements about motor units is TRUE?

Accepted Answer

All muscle fibers in a motor unit contract simultaneously when the motor neuron fires.

Question 13

According to Henneman's size principle, which motor units are recruited first during a low-force contraction?

Accepted Answer

Smallest motor units

Question 14

Which process is responsible for the relaxation of a muscle fiber after contraction?

Accepted Answer

Active transport of calcium ions back into the sarcoplasmic reticulum by Ca2+ ATPase

Question 15

Which regulatory protein blocks the myosin-binding site on actin in a relaxed muscle?

Accepted Answer

Tropomyosin

Question 16

If ATP is not available after death, what condition results in muscles remaining stiff?

Accepted Answer

Rigor mortis

Question 17

Which of the following best explains the latent period in skeletal muscle contraction?

Accepted Answer

It is the time needed to release Ca2+ from the sarcoplasmic reticulum and initiate cross-bridge cycling.

Question 18

Which of the following is TRUE regarding the interaction between myosin and actin during contraction?

Accepted Answer

Each myosin can interact with six actin filaments, and each actin can interact with three myosin filaments.

Question 19

Which of the following equations represents the re-cocking of the myosin head during the cross-bridge cycle?

Accepted Answer

$$\mathrm{M-ATP} \rightarrow \mathrm{M-ADP-P_i}$$

Module 4 – Muscle Physiology: Structure, Function, and Contraction Mechanisms

Study Guide - Practice Questions