Question 1

Which of the following best describes the role of calcium ions ($$\mathrm{Ca$$^{2+}$$}) in $$skeletal muscle contraction?

Accepted Answer

They bind to troponin, causing a conformational change that exposes myosin-binding sites on actin.

Question 2

A patient presents with muscle weakness, drooping eyelids, and difficulty swallowing. Laboratory tests reveal antibodies against acetylcholine receptors. What is the most likely diagnosis?

Accepted Answer

Myasthenia gravis

Question 3

Which connective tissue sheath surrounds individual muscle fibers?

Accepted Answer

Endomysium

Question 4

During the sliding filament model of contraction, what happens to the H zone and I band as the sarcomere shortens?

Accepted Answer

Both the H zone and I band disappear or become narrower.

Question 5

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

Accepted Answer

Presence of intercalated discs

Question 6

A muscle is attached to a weight that exceeds its peak tension-developing capability. When stimulated, the muscle develops tension but does not shorten. What type of contraction is this?

Accepted Answer

Isometric contraction

Question 7

Which metabolic pathway provides the most ATP for prolonged, low-intensity exercise?

Accepted Answer

Aerobic respiration

Question 8

What is the primary cause of rigor mortis after death?

Accepted Answer

Lack of ATP prevents detachment of myosin heads from actin

Question 9

Which of the following best explains why smooth muscle can maintain contraction for long periods with minimal energy expenditure?

Accepted Answer

Smooth muscle myofilaments latch together, maintaining tension with slow ATP hydrolysis.

Question 10

Which of the following is true regarding the role of the sarcoplasmic reticulum (SR) in muscle contraction?

Accepted Answer

It stores and releases calcium ions in response to an action potential.

Question 11

A marathon runner is likely to have a higher proportion of which muscle fiber type in their leg muscles?

Accepted Answer

Slow oxidative fibers (Type I)

Question 12

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

Accepted Answer

Action potential travels along T tubules

Question 13

Which of the following best describes the function of acetylcholinesterase at the neuromuscular junction?

Accepted Answer

It degrades acetylcholine in the synaptic cleft, terminating muscle contraction.

Question 14

Which of the following is a characteristic of unitary (visceral) smooth muscle?

Accepted Answer

It is electrically coupled by gap junctions and contracts as a single unit.

Question 15

Which of the following best explains why muscle fatigue occurs during intense exercise?

Accepted Answer

Ionic imbalances, accumulation of inorganic phosphate, and decreased glycogen contribute to fatigue.

Question 16

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

Accepted Answer

Cross bridge formation, power stroke, cross bridge detachment, cocking of myosin head

Question 17

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

Accepted Answer

Small motor units are recruited first, followed by larger ones as stimulus intensity increases.

Question 18

Which of the following is a function of muscle tone?

Accepted Answer

It keeps muscles firm, healthy, and ready to respond.

Question 19

Which of the following is true regarding the difference between smooth and skeletal muscle contraction?

Accepted Answer

Smooth muscle contraction is regulated by calmodulin binding to calcium.

Question 20

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

Accepted Answer

Isotonic concentric contraction

Muscles and Muscle Tissue: Structure, Function, and Contraction

Study Guide - Practice Questions

Study Guide - Flashcards