Question 1

A patient presents with muscle weakness and is diagnosed with Myasthenia Gravis. Which of the following best explains the physiological basis for their symptoms?

Accepted Answer

Antibodies block acetylcholine receptors at the neuromuscular junction, impairing muscle excitation.

Question 2

During a marathon, after 1 hour of running, which ATP-generating mechanism is primarily used by muscle cells?

Accepted Answer

Oxidative catabolism

Question 3

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

Accepted Answer

Maximum tension is produced when the sarcomere is at its optimal length, allowing for maximal crossbridge formation.

Question 4

A toxin blocks the release of acetylcholine at the neuromuscular junction. What is the most likely result?

Accepted Answer

Muscle paralysis due to inability to initiate contraction

Question 5

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

Accepted Answer

Smooth muscle contracts more slowly and uses significantly less ATP.

Question 6

Which of the following best explains why rigor mortis occurs after death?

Accepted Answer

ATP is no longer available to detach myosin heads from actin, causing sustained contraction.

Question 7

Which of the following changes is most likely to occur in skeletal muscle fibers as a result of endurance training?

Accepted Answer

Increase in oxidative enzymes and blood vessels

Question 8

A muscle fiber is stimulated 80 times per second, resulting in a sustained contraction with no relaxation. What is this phenomenon called?

Accepted Answer

Fused (complete) tetanus

Question 9

Which of the following is a primary function of single-unit (unitary) smooth muscle?

Accepted Answer

Coordinated contraction as a single unit due to gap junctions

Question 10

Which of the following best describes the role of calmodulin in smooth muscle contraction?

Accepted Answer

It binds calcium ions and activates myosin light-chain kinase (MLCK).

Question 11

A patient with Duchenne Muscular Dystrophy lacks functional dystrophin. Which of the following is a direct consequence of this defect?

Accepted Answer

Sarcolemma is not anchored to the endomysium, leading to muscle fiber degeneration.

Question 12

Which of the following best explains why muscle atrophy occurs during prolonged disuse?

Accepted Answer

Decrease in myofibrils and oxidative enzymes, leading to reduced muscle fiber diameter

Question 13

Which of the following is a likely cause of muscle fatigue during intense exercise?

Accepted Answer

Accumulation of calcium ions in the mitochondria interfering with oxidative catabolism

Question 14

Which of the following is true regarding the recovery period after exercise?

Accepted Answer

It involves excess postexercise oxygen consumption (EPOC) to restore homeostasis.

Question 15

Which of the following is a distinguishing feature of cardiac muscle compared to skeletal muscle?

Accepted Answer

Cardiac muscle fibers are connected by intercalated discs containing gap junctions.

Question 16

Which of the following best describes the effect of resistance (strength) training on skeletal muscle fibers?

Accepted Answer

Increase in the diameter of muscle fibers due to hypertrophy

Question 17

Which of the following is true regarding the sources of calcium ions for contraction in smooth muscle?

Accepted Answer

Calcium ions enter from both the sarcoplasmic reticulum and the extracellular fluid.

Question 18

Which of the following best explains why fused tetanus generates more tension than unfused tetanus?

Accepted Answer

Calcium ion concentration in the cytosol remains high, allowing more crossbridges to form.

Question 19

Which of the following is a function of smooth muscle in the digestive system?

Accepted Answer

Producing peristaltic waves to propel contents through the tract

Question 20

Which of the following best describes the 'latch state' in smooth muscle?

Accepted Answer

A state where smooth muscle maintains tension with minimal ATP consumption

Muscle Tissue and Physiology: Study Guide

Study Guide - Practice Questions

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