Question 1

Which of the following best describes the role of the sodium-potassium pump in maintaining the resting membrane potential of a muscle cell?

Accepted Answer

It moves 3 Na$$^+$$ ions out of the cell and 2 K$$^+$$ ions into the cell, using ATP.

Question 2

A patient is diagnosed with a genetic disorder that prevents the formation of intercalated discs. Which tissue would be most affected, and what would be the likely consequence?

Accepted Answer

Cardiac muscle; impaired electrical and mechanical coupling between cells.

Question 3

During the contraction phase of a muscle contraction, which event directly initiates the crossbridge cycle?

Accepted Answer

Calcium ions bind to troponin, causing tropomyosin to move and expose actin active sites.

Question 4

Which of the following best explains why action potentials only travel in one direction along an axon?

Accepted Answer

The absolute refractory period prevents the region behind the action potential from being re-excited.

Question 5

Which of the following is TRUE regarding the difference between ligand-gated and voltage-gated ion channels?

Accepted Answer

Ligand-gated channels open in response to chemical signals, while voltage-gated channels open in response to changes in membrane potential.

Question 6

A muscle fiber is stimulated to contract, but the sarcoplasmic reticulum fails to release calcium ions. Which step of muscle contraction will be directly impaired?

Accepted Answer

The binding of myosin to actin (crossbridge formation).

Question 7

Which of the following best describes the difference between continuous and saltatory conduction in neurons?

Accepted Answer

Saltatory conduction occurs in myelinated axons and is faster because action potentials jump between nodes of Ranvier.

Question 8

Which of the following best defines the length-tension relationship in skeletal muscle?

Accepted Answer

The amount of tension a muscle can produce depends on the degree of overlap between thick and thin filaments.

Question 9

Which of the following is a function of astrocytes in the central nervous system?

Accepted Answer

They regulate the extracellular environment and help form the blood-brain barrier.

Question 10

A patient is unable to perform voluntary movements but retains involuntary muscle contractions. Which division of the nervous system is most likely damaged?

Accepted Answer

Somatic motor division of the peripheral nervous system.

Question 11

Which of the following best describes the difference between type I and type II muscle fibers?

Accepted Answer

Type I fibers are slow-twitch, fatigue-resistant, and rely on aerobic metabolism; type II fibers are fast-twitch, fatigue quickly, and rely more on anaerobic metabolism.

Question 12

Which of the following events occurs during the repolarization phase of an action potential?

Accepted Answer

Voltage-gated K$$^+$$ channels open, allowing K$$^+ to $$exit the cell, making the membrane potential more negative.

Question 13

Which of the following best describes an isotonic eccentric contraction?

Accepted Answer

The muscle lengthens while generating force.

Question 14

Which of the following is TRUE regarding the events at a chemical synapse?

Accepted Answer

Neurotransmitter is released from the presynaptic neuron, diffuses across the synaptic cleft, and binds to receptors on the postsynaptic neuron.

Question 15

Which of the following best explains why fused (complete) tetanus produces greater tension than unfused (incomplete) tetanus?

Accepted Answer

In fused tetanus, stimuli arrive so rapidly that there is no relaxation phase, resulting in maximal sustained tension.

Question 16

Which of the following best describes the function of the elastic filament in a sarcomere?

Accepted Answer

It stabilizes the thick filament and allows the sarcomere to recoil after stretching.

Question 17

Which of the following is a characteristic of single-unit smooth muscle?

Accepted Answer

Cells are connected by gap junctions and contract as a unit, often found in the walls of hollow organs.

Question 18

Which of the following best describes the All-or-None principle of action potentials?

Accepted Answer

If threshold is reached, an action potential of the same size is always generated; if not, no action potential occurs.

Question 19

Which of the following changes occurs in muscle cells during endurance training?

Accepted Answer

Increased mitochondrial density and enhanced oxidative enzyme activity.

Question 20

Which of the following best describes the role of acetylcholine at the neuromuscular junction?

Accepted Answer

It binds to ligand-gated sodium channels on the muscle fiber, initiating an action potential.

Muscle Tissue, Physiology, and Introduction to the Nervous System

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