Question 1

Which of the following best describes the role of the sarcoplasmic reticulum (SR) in skeletal muscle contraction?

Accepted Answer

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

Question 2

During the sliding filament model of contraction, what happens to the sarcomere?

Accepted Answer

The thin filaments slide past the thick filaments, causing the sarcomere to shorten.

Question 3

Which connective tissue sheath surrounds an individual muscle fiber?

Accepted Answer

Endomysium

Question 4

A patient is unable to relax their muscles after contraction. Which enzyme is most likely deficient?

Accepted Answer

Acetylcholinesterase

Question 5

Which of the following is TRUE regarding the neuromuscular junction?

Accepted Answer

Acetylcholine (ACh) is released from the axon terminal and binds to receptors on the sarcolemma.

Question 6

Which of the following best explains why ATP is required for muscle relaxation?

Accepted Answer

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

Question 7

Which of the following is a characteristic unique to cardiac muscle tissue?

Accepted Answer

It contracts without nervous system stimulation due to pacemaker cells.

Question 8

A muscle fiber is stimulated by a motor neuron, but the resulting contraction does not move a load. What type of contraction is this?

Accepted Answer

Isometric contraction

Question 9

Which of the following best describes the function of T-tubules in skeletal muscle fibers?

Accepted Answer

They transmit the action potential deep into the muscle fiber.

Question 10

Which of the following events occurs first during excitation-contraction coupling?

Accepted Answer

Action potential travels along the sarcolemma and down T-tubules.

Question 11

Which of the following is a direct result of acetylcholine binding to its receptor on the sarcolemma?

Accepted Answer

Opening of ligand-gated sodium channels

Question 12

Which muscle fiber type is most resistant to fatigue and is primarily used during endurance activities?

Accepted Answer

Slow oxidative fibers

Question 13

A weightlifter is performing a bicep curl. As the muscle shortens to lift the weight, what type of contraction is occurring?

Accepted Answer

Concentric isotonic contraction

Question 14

Which of the following best explains the 'size principle' in motor unit recruitment?

Accepted Answer

Smaller motor units are recruited first, followed by larger ones as more force is needed.

Question 15

Which process provides the fastest way to regenerate ATP during the initial seconds of intense muscle activity?

Accepted Answer

Direct phosphorylation of ADP by creatine phosphate

Question 16

Which of the following is NOT a function of skeletal muscle?

Accepted Answer

Secretion of hormones

Question 17

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

Accepted Answer

It binds calcium ions, causing a conformational change that exposes myosin-binding sites on actin.

Question 18

A marathon runner's muscles are primarily using which metabolic pathway for ATP production during the race?

Accepted Answer

Aerobic respiration

Question 19

Which of the following is a distinguishing feature of smooth muscle compared to skeletal muscle?

Accepted Answer

Smooth muscle cells are spindle-shaped and lack striations.

Question 20

Which of the following best explains why muscle fatigue occurs during prolonged, strenuous activity?

Accepted Answer

ATP production fails to keep pace with ATP use, leading to ionic imbalances and accumulation of lactic acid.

Muscles and Muscle Tissue: Structure, Function, and Contraction

Study Guide - Practice Questions