Q: Which of the following best describes the role of the Na\textsuperscript{+}/K\textsuperscript{+} pump in maintaining the resting membrane potential of a muscle cell?

It actively transports 3 Na\textsuperscript{+} ions out of the cell and 2 K\textsuperscript{+} ions into the cell, using ATP.

Q: During the depolarization phase of muscle contraction, which ion primarily moves into the muscle cell, and through which type of channel?

Na\textsuperscript{+} through voltage-gated channels

Q: Which equation correctly represents the ATP yield from aerobic cellular respiration of one glucose molecule in muscle cells?

$$ \text{C}_6\text{H}_{12}\text{O}_6 + 6\text{O}_2 \rightarrow 6\text{CO}_2 + 6\text{H}_2\text{O} + 36\text{ATP} $$

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

ACh release → Na\textsuperscript{+} influx → Action potential → Ca\textsuperscript{2+} release → Crossbridge formation

Question 1

Which of the following best describes the role of the Na	extsuperscript{+}/K	extsuperscript{+} pump in maintaining the resting membrane potential of a muscle cell?

Accepted Answer

It actively transports 3 Na	extsuperscript{+} ions out of the cell and 2 K	extsuperscript{+} ions into the cell, using ATP.

Question 2

A patient is given a drug that blocks acetylcholine (ACh) receptors on the muscle fiber. What is the most likely physiological consequence?

Accepted Answer

Muscle paralysis because the muscle cannot be stimulated to contract.

Question 3

During the depolarization phase of muscle contraction, which ion primarily moves into the muscle cell, and through which type of channel?

Accepted Answer

Na	extsuperscript{+} through voltage-gated channels

Question 4

Which equation correctly represents the ATP yield from aerobic cellular respiration of one glucose molecule in muscle cells?

Accepted Answer

$$ 	ext{C}_6	ext{H}_{12}	ext{O}_6 + 6	ext{O}_2 ightarrow 6	ext{CO}_2 + 6	ext{H}_2	ext{O} + 36	ext{ATP} $$

Question 5

A marathon runner experiences muscle fatigue after prolonged exercise. Which metabolic pathway is primarily responsible for ATP production during the later stages of the race?

Accepted Answer

Aerobic respiration

Question 6

What would happen to muscle contraction if acetylcholinesterase is inhibited at the neuromuscular junction?

Accepted Answer

Muscle fibers would remain contracted due to continuous stimulation.

Question 7

Which of the following best explains the sliding filament model of muscle contraction?

Accepted Answer

Myosin heads pull actin filaments toward the center of the sarcomere, causing sarcomere shortening.

Question 8

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

Accepted Answer

ACh release → Na	extsuperscript{+} influx → Action potential → Ca	extsuperscript{2+} release → Crossbridge formation

Question 9

A child with malignant hyperthermia is exposed to an anesthetic that triggers excessive Ca	extsuperscript{2+} release from the sarcoplasmic reticulum. What is the most likely outcome?

Accepted Answer

Sustained muscle contraction and dangerous increase in body temperature

Question 10

Which of the following muscle energy sources provides ATP the fastest during the initial seconds of intense exercise?

Accepted Answer

Creatine phosphate system

Question 11

Which of the following is a consequence of anaerobic glycolysis in muscle cells?

Accepted Answer

Production of lactic acid and 2 ATP per glucose molecule

Question 12

Which of the following best describes muscle fatigue?

Accepted Answer

A state in which the muscle cannot contract even when stimulated

Question 13

In the crossbridge cycle, what causes the myosin head to detach from actin?

Accepted Answer

Binding of a new ATP molecule to the myosin head

Question 14

Which of the following would most likely occur if a person died clutching a drug vial and was discovered three days later?

Accepted Answer

Rigor mortis would be present due to lack of ATP, causing muscle stiffening.

Question 15

Which of the following is true regarding the role of troponin in muscle contraction?

Accepted Answer

Troponin binds to Ca	extsuperscript{2+}, causing tropomyosin to expose myosin-binding sites on actin.

Question 16

Which of the following best explains why nemaline myopathy causes muscle weakness?

Accepted Answer

Abnormalities in thin filament proteins disrupt the sliding filament mechanism, reducing force generation.

Question 17

Which of the following is a correct description of the sarcomere during contraction?

Accepted Answer

The Z-discs move closer together as actin filaments slide past myosin.

Question 18

Which of the following is true about the products of aerobic respiration in muscle cells?

Accepted Answer

Carbon dioxide and water are produced, along with a high yield of ATP.

Question 19

Which type of muscle fiber is most likely to be recruited during high-intensity, short-duration exercise when oxygen levels are low?

Accepted Answer

Fast glycolytic fibers

Muscle Physiology: How Muscle Cells Contract

Guida di studio - Domande di pratica

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