Question 1

Which of the following statements best describes the role of the sarcoplasmic reticulum in skeletal muscle contraction?

Accepted Answer

It stores and releases calcium ions, which trigger the sliding of filaments during contraction.

Question 2

A patient is unable to voluntarily move their limbs but their heart and digestive tract function normally. Which muscle type is most likely affected?

Accepted Answer

Skeletal muscle

Question 3

During the sliding filament theory, which event directly allows myosin heads to bind to actin filaments?

Accepted Answer

Calcium ions bind to regulatory proteins on actin, exposing myosin-binding sites.

Question 4

Which connective tissue layer wraps around a fascicle (bundle) of skeletal muscle fibers?

Accepted Answer

Perimysium

Question 5

What is the primary energy source that directly powers muscle contraction?

Accepted Answer

ATP

Question 6

Which of the following best explains why cardiac muscle cells contract at a steady rate?

Accepted Answer

They are regulated by an internal pacemaker.

Question 7

A muscle fiber is stimulated by a motor neuron, leading to depolarization. What is the next event in the action potential sequence?

Accepted Answer

More sodium channels open, allowing sodium ions to enter and create an action potential.

Question 8

Which muscle type is characterized by spindle-shaped, uninucleate cells and slow, sustained contractions?

Accepted Answer

Smooth muscle

Question 9

If a muscle is stimulated so rapidly that no evidence of relaxation is seen, what type of contraction is occurring?

Accepted Answer

Fused (complete) tetanus

Question 10

Which of the following is true regarding the 'all-or-none' law of muscle fiber contraction?

Accepted Answer

A muscle fiber will contract to its fullest extent when stimulated adequately.

Question 11

Which process regenerates ATP the fastest during short, intense muscle activity?

Accepted Answer

Direct phosphorylation of ADP by creatine phosphate

Question 12

A marathon runner experiences muscle fatigue after prolonged exercise. Which factor is LEAST likely to contribute to this fatigue?

Accepted Answer

Increase in muscle fiber size

Question 13

Which equation correctly represents the direct phosphorylation of ADP by creatine phosphate?

Accepted Answer

$$\mathrm{CP} + \mathrm{ADP} \rightarrow \mathrm{Creatine} + \mathrm{ATP}$$

Question 14

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

Accepted Answer

Maintaining posture and body position

Question 15

Which band in the sarcomere contains only thin filaments and is interrupted by the Z disc?

Accepted Answer

I band

Question 16

What is the role of acetylcholinesterase (AChE) at the neuromuscular junction?

Accepted Answer

It breaks down acetylcholine, ending muscle contraction.

Question 17

Which of the following best describes an isometric muscle contraction?

Accepted Answer

Tension increases, but the muscle does not shorten.

Question 18

A patient with a genetic defect in the protein myosin would most likely have problems with which aspect of muscle contraction?

Accepted Answer

Forming cross bridges between thick and thin filaments

Question 19

Which of the following is a result of aerobic (endurance) exercise?

Accepted Answer

Stronger, more flexible muscles with greater resistance to fatigue

Question 20

Which of the following best explains why muscle tone is important for overall health?

Accepted Answer

It keeps muscles firm, healthy, and constantly ready for action.

Study Notes: The Muscular System (Anatomy & Physiology)

Study Guide - Practice Questions