Question 1

Which of the following best describes the main function of the sarcoplasmic reticulum in skeletal muscle fibers?

Accepted Answer

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

Question 2

A patient is unable to voluntarily control the muscles in their digestive tract. Which type of muscle tissue is most likely affected?

Accepted Answer

Smooth muscle tissue

Question 3

Which connective tissue layer directly surrounds each individual muscle fiber?

Accepted Answer

Endomysium

Question 4

During the contraction cycle, what event directly triggers the exposure of the active site on actin?

Accepted Answer

Calcium ions ($$Ca^{2+}) $$bind to troponin, causing tropomyosin to shift.

Question 5

Which of the following is TRUE regarding the structure of a sarcomere?

Accepted Answer

The A band contains the entire length of the thick filament.

Question 6

A toxin blocks acetylcholinesterase (AChE) 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 7

Which of the following best explains why skeletal muscle fibers are multinucleated?

Accepted Answer

They are formed by the fusion of multiple myoblasts during development.

Question 8

A person is shivering in a cold environment. Which function of skeletal muscle is being demonstrated?

Accepted Answer

Maintaining body temperature through heat production

Question 9

Which of the following sequences correctly represents the order of structures from largest to smallest in skeletal muscle organization?

Accepted Answer

Muscle → Fascicle → Muscle fiber → Myofibril → Myofilament

Question 10

Which event occurs immediately after acetylcholine (ACh) binds to its receptors on the motor end plate?

Accepted Answer

Ligand-gated sodium channels open, allowing $$Na^+$$ influx and depolarization.

Question 11

Which of the following is FALSE regarding the crossbridge cycle?

Accepted Answer

ATP is not necessary for this cycle.

Question 12

A muscle fiber is unable to relax after contraction. Which of the following is the most likely cause?

Accepted Answer

ATP is unavailable to bind to the myosin head, preventing crossbridge detachment.

Question 13

Which structure is responsible for transmitting the action potential deep into the muscle fiber?

Accepted Answer

T-tubule (transverse tubule)

Question 14

Which protein directly covers the active sites on actin in a relaxed muscle fiber?

Accepted Answer

Tropomyosin

Question 15

A single motor neuron and all the muscle fibers it innervates is called a:

Accepted Answer

Motor unit

Question 16

Which of the following best describes the role of ATP in the contraction cycle?

Accepted Answer

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

Question 17

Which of the following is a unique feature of cardiac muscle tissue compared to skeletal muscle tissue?

Accepted Answer

Presence of intercalated discs

Question 18

Which of the following best explains why skeletal muscle is considered an organ?

Accepted Answer

It contains multiple tissue types, including muscle, connective, nervous, and vascular tissues.

Question 19

Which of the following best describes the function of the perimysium?

Accepted Answer

It surrounds each muscle fascicle.

Question 20

Which of the following changes occur in the sarcomere during muscle contraction?

Accepted Answer

The I band and H band decrease in width, while the A band remains the same.

The Muscular System: Structure, Function, and Contraction

Study Guide - Practice Questions