Question 1

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

Accepted Answer

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

Question 2

A patient is experiencing muscle weakness due to a defect in the acetylcholine receptors at the neuromuscular junction. Which process is most directly impaired?

Accepted Answer

Transmission of the nerve impulse to the muscle fiber membrane (sarcolemma).

Question 3

Which connective tissue layer surrounds an entire skeletal muscle?

Accepted Answer

Epimysium

Question 4

During the sliding filament model of muscle contraction, which event occurs immediately after calcium ions bind to troponin?

Accepted Answer

Tropomyosin shifts to expose binding sites on actin.

Question 5

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

Accepted Answer

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

Question 6

A muscle is stimulated so rapidly that no evidence of relaxation is seen and contractions are smooth and sustained. This state is called:

Accepted Answer

Fused (complete) tetanus

Question 7

Which of the following best describes an isotonic muscle contraction?

Accepted Answer

The muscle shortens while the tension remains constant.

Question 8

If a muscle does not contract for an extended period, what is the most likely physiological consequence?

Accepted Answer

The muscle will atrophy (shrink) due to lack of use.

Question 9

Which of the following is the correct order of muscle types from slowest to fastest contraction speed?

Accepted Answer

Smooth muscle, cardiac muscle, skeletal muscle

Question 10

A muscle fiber is stimulated by a motor neuron. Which neurotransmitter is released at the neuromuscular junction to initiate contraction?

Accepted Answer

Acetylcholine

Question 11

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

Accepted Answer

ATP binds to myosin heads, allowing them to detach from actin and reset for another power stroke.

Question 12

A patient with amyotrophic lateral sclerosis (ALS) experiences progressive paralysis. Which of the following best explains the underlying cause?

Accepted Answer

Degeneration of motor neurons prevents nerve impulses from reaching muscle fibers.

Question 13

Which of the following is a function of muscle tissue that is essential for homeostasis?

Accepted Answer

Constantly maintaining posture and body position.

Question 14

Which of the following best describes the relationship between the origin and insertion of a muscle during contraction?

Accepted Answer

The insertion moves toward the origin.

Question 15

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

Accepted Answer

It surrounds a bundle (fascicle) of muscle fibers.

Question 16

A muscle is acting as a synergist during a movement. What is its primary function?

Accepted Answer

To assist the prime mover and reduce undesirable movements.

Question 17

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

Accepted Answer

It is the plasma membrane of a muscle cell that conducts action potentials.

Question 18

During a muscle twitch, which phase corresponds to the time when calcium ions are actively transported back into the sarcoplasmic reticulum?

Accepted Answer

Relaxation phase

Question 19

Which of the following best explains why cardiac and smooth muscle can contract rhythmically without nervous stimulation?

Accepted Answer

They possess pacemaker cells that generate spontaneous action potentials.

Question 20

A muscle contraction in which the muscle develops tension but does not change length is called:

Accepted Answer

Isometric contraction

Muscle Structure, Function, and Physiology: Study Notes for Anatomy & Physiology

Guida di studio - Domande di pratica

Study guide - Flashcard