Question 1

Which of the following best describes the difference in stimulation between cardiac muscle and skeletal muscle?

Accepted Answer

Cardiac muscle is stimulated by pacemaker cells and autonomic nervous system, while skeletal muscle is stimulated by somatic motor neurons.

Question 2

Which structure in a skeletal muscle fiber is responsible for storing and releasing calcium ions during muscle contraction?

Accepted Answer

Sarcoplasmic reticulum

Question 3

A patient presents with muscle weakness and rapid fatigue. Laboratory tests reveal antibodies against acetylcholine receptors. Which disorder is most likely?

Accepted Answer

Myasthenia gravis

Question 4

During a muscle contraction, which protein directly binds to calcium ions to initiate the exposure of binding sites on actin?

Accepted Answer

Troponin

Question 5

Which of the following best explains the 'graded muscle response' in skeletal muscle?

Accepted Answer

It is the variation in muscle contraction strength due to changes in frequency and number of motor units stimulated.

Question 6

Which of the following equations correctly represents the relationship between force, lever arm, and torque in muscle movement?

Accepted Answer

$$T = F 	imes r$$

Question 7

A marathon runner experiences muscle fatigue after prolonged exercise. Which energy system is primarily responsible for this fatigue?

Accepted Answer

Anaerobic glycolysis

Question 8

Which of the following is NOT a component of the thin filament in skeletal muscle?

Accepted Answer

Myosin

Question 9

A muscle contraction is initiated when the membrane potential reaches a threshold. Which term best describes the rapid change in membrane potential during this process?

Accepted Answer

Depolarization

Question 10

Which of the following best describes the role of ATP in muscle contraction?

Accepted Answer

ATP is required for the detachment of myosin heads from actin after the power stroke.

Question 11

Which of the following best explains why cardiac muscle cells do not experience tetanus?

Accepted Answer

Cardiac muscle cells have a long refractory period that prevents summation of contractions.

Question 12

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

Accepted Answer

Action potential in sarcolemma, release of calcium from sarcoplasmic reticulum, binding of myosin to actin

Question 13

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

Accepted Answer

Isotonic contractions change muscle length with constant tension, while isometric contractions generate tension without changing muscle length.

Question 14

Which of the following is a symptom of muscular dystrophy?

Accepted Answer

Progressive muscle weakness and degeneration

Question 15

Which of the following factors would most likely increase the velocity of muscle contraction?

Accepted Answer

Increased number of fast-twitch muscle fibers

Question 16

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

Accepted Answer

It transmits the action potential from the motor neuron to the muscle fiber.

Question 17

A muscle is attached to a bone at two points: the origin and the insertion. Which statement is correct regarding these attachments?

Accepted Answer

The origin is typically the fixed attachment, while the insertion is the movable attachment.

Question 18

Which of the following correctly describes the effect of increased extracellular potassium on the resting membrane potential of a muscle cell?

Accepted Answer

It depolarizes the membrane, making it more excitable.

Question 19

Which of the following is the correct formula for calculating the mechanical advantage of a lever in the human body?

Accepted Answer

$$	ext{Mechanical Advantage} = \frac{	ext{Effort Arm}}{	ext{Load Arm}}$$

Question 20

Which of the following is a direct effect of muscle atrophy?

Accepted Answer

Decrease in muscle strength and mass

Muscular System: Structure, Function, and Physiology Study Guide

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