Question 1

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

Accepted Answer

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

Question 2

A patient is given a drug that inhibits the active transport of $$\mathrm{Ca$$^{2+}$$}$$ back into the sarcoplasmic reticulum. What is the most likely effect on muscle function?

Accepted Answer

Muscle relaxation would be impaired, leading to prolonged contraction.

Question 3

Which connective tissue layer directly surrounds a muscle fascicle?

Accepted Answer

Perimysium

Question 4

During the power stroke of muscle contraction, which event occurs?

Accepted Answer

The myosin head pivots, pulling the actin filament toward the center of the sarcomere.

Question 5

Which of the following best explains why marathon runners have a higher proportion of slow-twitch muscle fibers?

Accepted Answer

Slow-twitch fibers are specialized for continuous, long-duration contractions and resist fatigue.

Question 6

A person is exposed to curare, a poison that blocks acetylcholine receptors at the motor end plate. What is the most immediate effect on skeletal muscle?

Accepted Answer

Muscle paralysis due to failure of action potential generation in the muscle fiber.

Question 7

Which of the following is a by-product of anaerobic respiration in muscle fibers during intense exercise?

Accepted Answer

Lactic acid

Question 8

If acetylcholinesterase is absent from the synaptic cleft, what would be the effect on muscle contraction?

Accepted Answer

Muscle fibers would remain contracted due to continuous stimulation.

Question 9

Which of the following best describes an isometric contraction?

Accepted Answer

Muscle tension increases but the muscle does not change length, such as holding a heavy object stationary.

Question 10

Which protein anchors myofibrils to the sarcolemma, helping maintain the structural integrity of muscle fibers?

Accepted Answer

Dystrophin

Question 11

A muscle fiber at rest has a higher concentration of sodium ions ($$\mathrm{Na^+}) in $$which location?

Accepted Answer

Outside the cell

Question 12

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

Accepted Answer

Visceral smooth muscle contracts as a single unit and is found in the intestines; multi-unit smooth muscle contracts independently and is found in the iris of the eye.

Question 13

Which event occurs during depolarization of a muscle fiber's action potential?

Accepted Answer

$$\mathrm{Na^+}$$ ions rapidly enter the cell, making the inside more positive.

Question 14

Which type of muscle tissue is striated, branched, and joined by intercalated discs?

Accepted Answer

Cardiac muscle

Question 15

What is the primary role of myoglobin in muscle tissue?

Accepted Answer

It stores oxygen for use during muscle contraction.

Question 16

Which of the following best explains why diseases that affect skeletal muscle contraction can be life-threatening?

Accepted Answer

They can impair muscles essential for breathing, such as the diaphragm.

Question 17

Which of the following is true regarding the effect of increasing the number of motor units recruited during a muscle contraction?

Accepted Answer

The force of contraction increases, allowing heavier objects to be lifted.

Question 18

Which of the following best describes the difference between concentric and eccentric contractions?

Accepted Answer

Concentric contractions shorten the muscle as it contracts; eccentric contractions lengthen the muscle while it contracts.

Question 19

Which of the following is a key difference between smooth and skeletal muscle cells?

Accepted Answer

Smooth muscle cells lack striations, while skeletal muscle cells are striated.

Question 20

Which of the following best describes the lag phase of a muscle twitch?

Accepted Answer

It is the period between the application of a stimulus and the beginning of contraction.

Guided Study for ANP: Muscular System (Chapter 10)

Study Guide - Practice Questions

Study Guide - Flashcards