Question 1

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

Accepted Answer

Calcium ions bind to troponin, causing tropomyosin to move away from myosin binding sites on actin.

Question 2

During excitation-contraction coupling in skeletal muscle, which event occurs immediately after the action potential travels down the T-tubule?

Accepted Answer

Calcium ions are released from the sarcoplasmic reticulum into the cytosol.

Question 3

A muscle twitch consists of three phases. Which phase is characterized by cross bridge formation and increasing tension?

Accepted Answer

Period of contraction

Question 4

Which of the following statements about ATP regeneration in skeletal muscle is correct?

Accepted Answer

Direct phosphorylation of ADP by creatine phosphate does not require oxygen and is the fastest way to regenerate ATP.

Question 5

A patient is exercising at high intensity and reaches their anaerobic threshold. What metabolic change occurs in their muscle cells?

Accepted Answer

Pyruvate is converted to lactate due to insufficient oxygen.

Question 6

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

Accepted Answer

Ionic imbalances, decreased ATP, and increased magnesium disrupt normal muscle function.

Question 7

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

Accepted Answer

$$ADP + CP \rightarrow ATP + C$$

Question 8

A motor unit is defined as:

Accepted Answer

A motor neuron and all the muscle fibers it innervates.

Question 9

Which factor does NOT increase the force of skeletal muscle contraction?

Accepted Answer

Decreasing the size of muscle fibers.

Question 10

Which statement about the length-tension relationship in skeletal muscle is correct?

Accepted Answer

Maximum tension is generated when the muscle is at an optimal resting length, allowing maximal cross bridge formation.

Question 11

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

Accepted Answer

Smooth muscle fibers are spindle-shaped, have a single nucleus, and lack striations.

Question 12

In smooth muscle contraction, which protein does $$Ca^{2+}$$ bind to in order to initiate contraction?

Accepted Answer

Calmodulin

Question 13

Which of the following best describes the arrangement of smooth muscle in the walls of hollow organs?

Accepted Answer

Two layers: longitudinal and circular, oriented at right angles to each other.

Question 14

Which statement about the sources of $$Ca^{2+}$$ for smooth muscle contraction is correct?

Accepted Answer

Most $$Ca^{2+}$$ comes from the extracellular fluid, with some from the sarcoplasmic reticulum.

Question 15

Which of the following is true regarding the mechanism of contraction in smooth muscle?

Accepted Answer

Contraction is slow and synchronized, often involving gap junctions.

Question 16

Which of the following is a function of ATP in muscle contraction?

Accepted Answer

ATP is required to detach myosin heads from actin and to energize the power stroke.

Question 17

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

Accepted Answer

Motor units with the smallest muscle fibers are recruited first, followed by larger units as stimulus intensity increases.

Question 18

After intense exercise, which process is responsible for restoring muscle cells to their pre-exercise state and is referred to as excess postexercise oxygen consumption (EPOC)?

Accepted Answer

Replenishing oxygen reserves, reconverting lactate to pyruvate, replacing glycogen stores, and resynthesizing ATP and creatine phosphate.

Question 19

Which of the following is NOT a characteristic of smooth muscle fibers?

Accepted Answer

Presence of troponin in thin filaments.

Muscles and Muscle Tissue Part 2: Study Guide

Guida di studio - Domande di pratica

Study guide - Flashcard