Question 1

Which of the following best describes the role of the sarcoplasmic reticulum in skeletal muscle contraction?

Accepted Answer

It stores and releases calcium ions ($$\mathrm{Ca$$^{2+}$$}) $$necessary for muscle contraction.

Question 2

A patient is exposed to a toxin that inhibits acetylcholinesterase at the neuromuscular junction. What is the most likely effect on muscle contraction?

Accepted Answer

Continuous stimulation and prolonged contraction of the muscle due to excess acetylcholine.

Question 3

Which of the following best explains why ATP is required for muscle relaxation after contraction?

Accepted Answer

ATP is needed to pump $$\mathrm{Ca$$^{2+}$$}$$ back into the sarcoplasmic reticulum.

Question 4

During the sliding filament model of contraction, which event directly causes the power stroke?

Accepted Answer

Release of ADP and inorganic phosphate ($$\mathrm{P_i}) $$from the myosin head.

Question 5

Which type of muscle fiber would be most prevalent in the quadriceps of a marathon runner, and why?

Accepted Answer

Slow oxidative fibers, because they are fatigue-resistant and use aerobic metabolism.

Question 6

A muscle is contracting isometrically. Which of the following best describes this contraction?

Accepted Answer

The muscle develops tension but does not change length.

Question 7

Which of the following best describes the function of myelin in the nervous system?

Accepted Answer

It increases the speed of action potential conduction along axons.

Question 8

If a neuron is at rest, which of the following statements is correct regarding ion concentrations and membrane potential?

Accepted Answer

The inside of the neuron is negatively charged relative to the outside, with higher $$\mathrm{K^+}$$ inside and higher $$\mathrm{Na^+}$$ outside.

Question 9

Which of the following best explains the 'all or nothing' principle of action potentials?

Accepted Answer

Once threshold is reached, an action potential of fixed size is generated; subthreshold stimuli do not produce action potentials.

Question 10

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

Accepted Answer

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

Question 11

A person is performing a high-intensity, short-duration activity such as sprinting. Which ATP regeneration pathway is primarily used, and what is a byproduct?

Accepted Answer

Anaerobic glycolysis; lactic acid is produced.

Question 12

Which of the following best describes the difference between temporal and spatial summation in neurons?

Accepted Answer

Temporal summation involves multiple signals from one presynaptic neuron over time; spatial summation involves simultaneous signals from multiple presynaptic neurons.

Question 13

Which of the following is true regarding the role of calcium ($$\mathrm{Ca$$^{2+}$$}) in $$skeletal muscle contraction?

Accepted Answer

Calcium binds to troponin, causing tropomyosin to move and expose binding sites on actin.

Question 14

Which of the following best describes saltatory conduction in myelinated axons?

Accepted Answer

Action potentials jump from one node of Ranvier to the next, increasing conduction speed.

Question 15

Which of the following is the primary function of wave summation in muscle contraction?

Accepted Answer

To increase the force of contraction by increasing the frequency of stimulation.

Question 16

Which of the following best describes the role of the Na+/K+ pump in neurons?

Accepted Answer

It maintains the resting membrane potential by moving 3 $$\mathrm{Na^+}$$ out and 2 $$\mathrm{K^+} in$$, using ATP.

Question 17

Which of the following is true regarding motor unit recruitment during muscle contraction?

Accepted Answer

Smaller motor units are recruited first, followed by larger ones as more force is needed.

Question 18

Which of the following best describes the difference between an agonist (prime mover) and an antagonist muscle?

Accepted Answer

The agonist produces the primary movement, while the antagonist opposes that movement.

Question 19

Which of the following is a characteristic unique to smooth muscle compared to skeletal muscle?

Accepted Answer

Smooth muscle lacks striations and has spindle-shaped cells.

Question 20

Which neurotransmitter is released at the neuromuscular junction to initiate muscle contraction?

Accepted Answer

Acetylcholine

Anatomy & Physiology: Muscles, Muscular System, and Nervous System Study Guide

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