Question 1

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

Accepted Answer

They produce myelin to insulate axons, increasing the speed of action potential conduction.

Question 2

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

Accepted Answer

Prolonged muscle contraction due to increased acetylcholine in the synaptic cleft.

Question 3

Which equation best represents the Nernst equation for calculating the equilibrium potential ($$E_{ion}) of an $$ion across a neuronal membrane?

Accepted Answer

$$E_{ion} = \frac{RT}{zF} \ln \left( \frac{[ion]_{out}}{[ion]_{in}} \right) $$

Question 4

During the absolute refractory period of an action potential, which statement is true regarding voltage-gated sodium channels?

Accepted Answer

They are inactivated and cannot be reopened until the membrane repolarizes.

Question 5

Which of the following best explains why action potentials propagate faster in myelinated axons compared to unmyelinated axons?

Accepted Answer

Saltatory conduction allows action potentials to jump between nodes of Ranvier, reducing ion leakage and increasing speed.

Question 6

Which of the following is a major difference between acetylcholine and norepinephrine as neurotransmitters?

Accepted Answer

Acetylcholine acts on cholinergic receptors, while norepinephrine acts on adrenergic receptors.

Question 7

A muscle fiber is stimulated repeatedly at a frequency that allows partial relaxation between contractions. Which term best describes this phenomenon?

Accepted Answer

Unfused (incomplete) tetanus

Question 8

Which of the following best describes the relationship between the size of a stimulus and the amplitude of a graded potential?

Accepted Answer

The amplitude of a graded potential increases with the size of the stimulus, but decays with distance from the site of stimulation.

Question 9

Which of the following best describes the events that occur during the contraction phase of a muscle twitch?

Accepted Answer

Cross-bridge cycling occurs as myosin binds to actin, resulting in muscle tension.

Question 10

Which of the following statements correctly compares spatial and temporal summation of graded potentials?

Accepted Answer

Spatial summation involves multiple presynaptic neurons firing simultaneously, while temporal summation involves a single neuron firing repeatedly in quick succession.

Question 11

Which of the following best describes the sliding filament mechanism of muscle contraction?

Accepted Answer

Myosin heads bind to actin, pull the thin filaments toward the center of the sarcomere, and shorten the muscle.

Question 12

Which of the following is true regarding the composition and arrangement of myofilaments in smooth muscle compared to skeletal muscle?

Accepted Answer

Smooth muscle lacks sarcomeres and has irregularly arranged actin and myosin filaments.

Question 13

Which of the following best describes the role of ATP in skeletal muscle relaxation?

Accepted Answer

ATP binds to myosin, causing it to detach from actin and allowing muscle relaxation.

Question 14

Which of the following statements about the resting membrane potential of a neuron is correct?

Accepted Answer

It is primarily established by the movement of potassium ions through leak channels.

Question 15

Which of the following best describes the difference between isotonic and isometric muscle contractions?

Accepted Answer

Isotonic contractions produce movement as muscle length changes, while isometric contractions generate tension without changing muscle length.

Question 16

Which of the following best describes the effect of increasing the number of motor units recruited during a muscle contraction?

Accepted Answer

Muscle tension increases as more muscle fibers are activated.

Question 17

Which of the following best describes the events at a chemical synapse after an action potential arrives at the presynaptic terminal?

Accepted Answer

Voltage-gated calcium channels open, neurotransmitter is released, and binds to receptors on the postsynaptic cell.

Question 18

Which of the following best describes the change in the sarcomere during muscle contraction?

Accepted Answer

The I-band and H-zone decrease in length, while the A-band remains unchanged.

Question 19

Which of the following best describes the difference between electrical and chemical synapses?

Accepted Answer

Electrical synapses transmit signals via gap junctions, allowing direct ion flow, while chemical synapses use neurotransmitters to transmit signals across a synaptic cleft.

Fundamentals of the Nervous and Muscular Systems

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