Question 1

Which of the following best describes the main difference between skeletal, cardiac, and smooth muscle tissue?

Accepted Answer

Skeletal muscle is striated and voluntary, cardiac muscle is striated and involuntary, and smooth muscle is non-striated and involuntary.

Question 2

A single muscle cell is also known as a:

Accepted Answer

Muscle fiber

Question 3

Which protein anchors thin filaments to the Z disc and helps maintain the structure of the sarcomere?

Accepted Answer

Titin

Question 4

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

Accepted Answer

Tropomyosin shifts to expose myosin-binding sites on actin

Question 5

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 contraction.

Question 6

A patient is exposed to a toxin that blocks acetylcholine receptors at the neuromuscular junction. What is the most likely effect on muscle contraction?

Accepted Answer

Muscle contraction will not occur because the action potential cannot be initiated.

Question 7

Which of the following correctly matches the ion channel type with its stimulus and location in a skeletal muscle cell?

Accepted Answer

Voltage-gated ion channels open in response to changes in membrane potential and are found along the sarcolemma and T-tubules.

Question 8

Which phase of a muscle twitch corresponds to the time when cross-bridges are actively cycling and tension is increasing?

Accepted Answer

Contraction phase

Question 9

A muscle is contracting but not changing in length while holding a heavy object stationary. This is an example of:

Accepted Answer

Isometric contraction

Question 10

Which of the following best explains why rigor mortis occurs after death?

Accepted Answer

ATP is no longer produced, so myosin heads cannot detach from actin.

Question 11

Which of the following is NOT a mechanism by which muscle fibers generate ATP during exercise?

Accepted Answer

Glycogenolysis without ATP production

Question 12

Which of the following muscle fiber types is most resistant to fatigue and best suited for endurance activities?

Accepted Answer

Slow oxidative fibers

Question 13

Which of the following best describes the difference between unitary and multi-unit smooth muscle?

Accepted Answer

Unitary smooth muscle fibers are electrically coupled via gap junctions, while multi-unit smooth muscle fibers are not.

Question 14

Which of the following events occurs during the relaxation phase of muscle contraction?

Accepted Answer

Calcium ions are pumped back into the sarcoplasmic reticulum.

Question 15

A drug increases the frequency of action potentials reaching a skeletal muscle fiber. Which of the following is the most likely result?

Accepted Answer

The muscle will enter incomplete tetanus, and with further increase, complete tetanus.

Question 16

Which of the following best describes muscle tone?

Accepted Answer

A state of sustained partial contraction that keeps muscles firm and ready to respond.

Question 17

Which of the following is a factor that increases the force generated by a contracting muscle?

Accepted Answer

Muscle fibers starting contraction at optimal resting length

Question 18

Which of the following best explains why smooth muscle contraction is generally slower and more sustained than skeletal muscle contraction?

Accepted Answer

Smooth muscle uses calmodulin instead of troponin for calcium binding, and cross-bridge cycling is slower.

Question 19

Which of the following best describes the process of recruitment in skeletal muscle contraction?

Accepted Answer

Activating additional motor units to increase muscle tension

Question 20

During an action potential in a skeletal muscle cell, which of the following occurs during the depolarization phase?

Accepted Answer

Voltage-gated sodium channels open and sodium ions enter the cell.

Muscle and Muscle Tissue: Structure, Function, and Physiology

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