Question 1

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

Accepted Answer

Titin allows muscle fibers to stretch and recoil, helping them return to their original length after contraction.

Question 2

A patient is diagnosed with Duchenne Muscular Dystrophy. Which of the following best explains the underlying cause of this disease?

Accepted Answer

A defective gene for the protein dystrophin leads to breakdown of muscle fibers, which are replaced by fatty and fibrous tissue.

Question 3

Which of the following statements about the resting membrane potential in skeletal muscle fibers is correct?

Accepted Answer

The resting membrane potential is typically negative inside the cell due to the activity of the Na	extsuperscript{+}/K	extsuperscript{+} ATPase pump.

Question 4

During muscle contraction, which event directly triggers the release of calcium ions from the sarcoplasmic reticulum?

Accepted Answer

Propagation of an action potential along the T-tubule.

Question 5

Which equation correctly represents the immediate source of energy for muscle contraction?

Accepted Answer

$$\mathrm{Creatine\ phosphate} + \mathrm{ADP} \rightarrow \mathrm{Creatine} + \mathrm{ATP}$$

Question 6

A person lifts a heavy box and their biceps muscle shortens while maintaining the same level of tension. What type of contraction is this?

Accepted Answer

Isotonic concentric contraction

Question 7

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

Accepted Answer

Depletion of oxygen forces reliance on glycolysis, leading to accumulation of key metabolites and interference with oxidative catabolism.

Question 8

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

Accepted Answer

Cardiac muscle cells are connected by intercalated discs, allowing coordinated contraction.

Question 9

Which process is responsible for the breakdown of glucose into 2 ATP molecules without the use of oxygen?

Accepted Answer

Glycolytic catabolism

Question 10

A patient receives botulinum toxin injections for cosmetic purposes. What is the mechanism by which this toxin affects muscle contraction?

Accepted Answer

It blocks the release of acetylcholine at the neuromuscular junction, preventing muscle contraction.

Question 11

Which of the following best describes the sliding-filament mechanism of muscle contraction?

Accepted Answer

Thin filaments slide past thick filaments, generating tension and shortening the sarcomere.

Question 12

Which type of muscle fiber is best suited for endurance activities such as marathon running?

Accepted Answer

Slow-twitch fibers with small diameters, high myoglobin, and aerobic metabolism

Question 13

Which of the following correctly describes the role of troponin in muscle contraction?

Accepted Answer

Troponin binds calcium ions, causing tropomyosin to move and expose active sites on actin.

Question 14

Which of the following is true regarding smooth muscle contraction?

Accepted Answer

Smooth muscle contraction is initiated by calcium binding to calmodulin, which activates myosin light chain kinase.

Question 15

Which of the following best explains the difference between unitary (visceral) and multi-unit smooth muscle?

Accepted Answer

Unitary smooth muscle is joined by gap junctions and contracts as a unit, while multi-unit smooth muscle contracts independently.

Question 16

Which of the following best describes the effect of endurance training on skeletal muscle?

Accepted Answer

It increases the number of mitochondria and enzymes for aerobic metabolism.

Question 17

Which of the following is the correct sequence of events in excitation-contraction coupling in skeletal muscle?

Accepted Answer

Action potential travels along sarcolemma → calcium released from sarcoplasmic reticulum → troponin binds calcium → crossbridge formation

Question 18

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

Accepted Answer

Excess calcium ions in the cytosol prevent release of myosin heads from actin due to lack of ATP.

Question 19

Which of the following equations represents the activity of the Na	extsuperscript{+}/K	extsuperscript{+} ATPase pump in maintaining ion gradients?

Accepted Answer

$$3\ \mathrm{Na}^+_{\mathrm{in}} + 2\ \mathrm{K}^+_{\mathrm{out}} + \mathrm{ATP} \rightarrow 3\ \mathrm{Na}^+_{\mathrm{out}} + 2\ \mathrm{K}^+_{\mathrm{in}} + \mathrm{ADP} + \mathrm{P}_i$$

Muscle Tissue & Physiology – Chapter 10 Study Notes

Guida di studio - Domande di pratica

Study guide - Flashcard