Question 1

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

Accepted Answer

Calcium ions bind to troponin, causing a conformational change that moves tropomyosin away from actin's binding sites.

Question 2

A patient is experiencing muscle fatigue after intense exercise. Which of the following is LEAST likely to contribute to muscle fatigue?

Accepted Answer

Excessive oxygen delivery to muscle fibers

Question 3

During the sliding filament model of contraction, what happens when the myosin head binds to actin?

Accepted Answer

The myosin head acts as a ratchet, generating tension and pulling the thin filament toward the center of the sarcomere.

Question 4

Which of the following is TRUE regarding the difference between isotonic and isometric muscle contractions?

Accepted Answer

Isotonic contractions decrease muscle length and move the load, while isometric contractions increase tension without shortening the muscle.

Question 5

Which structure in skeletal muscle is responsible for propagating the action potential deep into the muscle fiber?

Accepted Answer

T tubules

Question 6

A muscle twitch consists of three phases. Which phase corresponds to the time when $$Ca^{2+} is $$reabsorbed into the sarcoplasmic reticulum and muscle tension decreases?

Accepted Answer

Period of relaxation

Question 7

Which of the following best explains why skeletal muscle fibers are multinucleated?

Accepted Answer

They are formed by the fusion of multiple embryonic cells called myoblasts.

Question 8

Which process is responsible for the rapid removal of acetylcholine (ACh) from the synaptic cleft after it binds to its receptor?

Accepted Answer

Destruction by acetylcholinesterase

Question 9

A marathon runner is experiencing oxygen debt after a race. Which of the following processes is NOT part of restoring muscle cells to their resting state?

Accepted Answer

Increasing the rate of anaerobic glycolysis

Question 10

Which of the following is a correct formula for the regeneration of ATP from creatine phosphate (CP) in muscle cells?

Accepted Answer

$$ADP + CP \rightarrow ATP + Creatine$$

Question 11

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

Accepted Answer

It contracts at a steady rate set by a pacemaker and is not under voluntary control.

Question 12

Which of the following best describes the role of the sarcoplasmic reticulum (SR) in muscle contraction?

Accepted Answer

It stores and releases $$Ca^{2+}$$ ions necessary for contraction.

Question 13

Which type of muscle tissue is responsible for peristalsis in the digestive tract?

Accepted Answer

Smooth muscle

Question 14

A muscle fiber is stretched to 120% of its normal resting length. What effect does this have on the degree of muscle contraction?

Accepted Answer

Contraction strength decreases because fewer cross bridges can form.

Question 15

Which of the following is TRUE about the organization of myofilaments in smooth muscle compared to skeletal muscle?

Accepted Answer

Thick filaments in smooth muscle have heads along their entire length, allowing powerful contractions.

Question 16

Which of the following best explains the phenomenon of wave summation in muscle contraction?

Accepted Answer

It results from frequently delivered stimuli that do not allow the muscle to completely relax, increasing contractile force.

Question 17

Which of the following is a function of muscle tone?

Accepted Answer

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

Question 18

Which of the following is TRUE regarding multiunit smooth muscle?

Accepted Answer

It is found in large airways, large arteries, arrector pili muscles, and internal eye muscles.

Question 19

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

Accepted Answer

Action potential travels along sarcolemma $$\rightarrow Ca$^{2+}$$ released from SR $$\rightarrow Ca$^{2+}$$ binds to troponin $$\rightarrow$$ tropomyosin moves $$\rightarrow$$ contraction occurs

Muscles and Muscle Tissue: Structure, Function, and Types

Guida di studio - Domande di pratica

Study guide - Flashcard