Question 1

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

Accepted Answer

Calcium binds to troponin, causing tropomyosin to shift and expose the myosin-binding sites on actin.

Question 2

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

Accepted Answer

Muscle contraction will be prolonged due to continuous stimulation by acetylcholine.

Question 3

Which connective tissue layer surrounds individual muscle fibers?

Accepted Answer

Endomysium

Question 4

During the sliding filament theory of muscle contraction, which event occurs immediately after ATP binds to the myosin head?

Accepted Answer

The myosin head detaches from actin.

Question 5

Which of the following best explains why saltatory conduction is faster than continuous conduction?

Accepted Answer

Myelin sheaths allow action potentials to jump between nodes of Ranvier, reducing the number of action potentials needed.

Question 6

A muscle fiber is stimulated so rapidly that it does not have time to relax between stimuli, resulting in a sustained contraction. This phenomenon is known as:

Accepted Answer

Tetanus

Question 7

Which of the following is true regarding the resting membrane potential ($$V_{\mathrm{rest}}) of a $$typical neuron?

Accepted Answer

$$V_{\mathrm{rest}} is $$approximately $$-70\ \mathrm{mV}$$ due to the differential distribution of $$\mathrm{Na^+}$$ and $$\mathrm{K^+}$$ ions.

Question 8

Which of the following best describes an isotonic muscle contraction?

Accepted Answer

The muscle changes length while the tension remains constant.

Question 9

A neuron receives a stimulus that causes the membrane potential to become less negative, moving from $$-70\ \mathrm{mV} to$$ $$-55\ \mathrm{mV}. $$This process is called:

Accepted Answer

Depolarization

Question 10

Which of the following is a characteristic of oxidative (slow-twitch) muscle fibers compared to glycolytic (fast-twitch) fibers?

Accepted Answer

They have more mitochondria and are better suited for endurance activities.

Question 11

Which glial cell is responsible for forming the myelin sheath in the central nervous system (CNS)?

Accepted Answer

Oligodendrocyte

Question 12

During an action potential, which ion channels open first, and in which direction do the ions move?

Accepted Answer

Voltage-gated sodium channels open first, allowing $$\mathrm{Na^+} to $$enter the cell.

Question 13

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

Accepted Answer

It binds to receptors on the sarcolemma, causing sodium channels to open and initiate an action potential.

Question 14

A muscle is unable to generate force even though it is being stimulated. Which of the following is a likely cause of this type of muscle fatigue?

Accepted Answer

Depletion of acetylcholine at the neuromuscular junction

Question 15

Which of the following best describes the arrangement of a motor unit?

Accepted Answer

A single motor neuron and all the muscle fibers it innervates

Question 16

Which of the following would increase the velocity of muscle contraction?

Accepted Answer

Recruiting more fast-twitch muscle fibers

Question 17

Which of the following best explains why the absolute refractory period occurs during an action potential?

Accepted Answer

Voltage-gated sodium channels are inactivated and cannot reopen until the membrane repolarizes.

Question 18

Which of the following best describes the role of the perimysium in muscle structure?

Accepted Answer

It surrounds bundles of muscle fibers called fascicles.

Question 19

A patient has a genetic mutation that prevents the formation of voltage-gated sodium channels in neurons. Which of the following would most likely occur?

Accepted Answer

Action potentials would not be generated, leading to loss of neural signaling.

Question 20

Which of the following best describes the function of astrocytes in the central nervous system?

Accepted Answer

They provide structural and metabolic support for neurons and help maintain the blood-brain barrier.

Comprehensive Study Guidance for Muscular and Nervous System Exam Topics

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