Question 1

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

Accepted Answer

It stores and releases calcium ions $$\mathrm{(Ca$$^{2+}$$)}$$, which trigger contraction.

Question 2

A patient is unable to maintain posture and experiences frequent falls. Which muscle function is most likely impaired?

Accepted Answer

Maintaining posture and body position

Question 3

During the cross-bridge cycle, what is the immediate consequence of ATP binding to the myosin head?

Accepted Answer

The myosin head detaches from the actin filament.

Question 4

Which of the following is TRUE regarding the difference between skeletal and cardiac muscle?

Accepted Answer

Skeletal muscle is voluntary and striated, while cardiac muscle is involuntary and striated.

Question 5

What is the primary function of titin (connectin) in muscle tissue?

Accepted Answer

It helps the muscle cell spring back into shape after stretching, acting as an elastic element.

Question 6

A muscle cell is exposed to a toxin that blocks voltage-gated sodium channels. Which step of muscle excitation will be directly affected?

Accepted Answer

Generation and propagation of the action potential (AP)

Question 7

Which of the following pathways provides the fastest way for skeletal muscle fibers to regenerate ATP during short, intense activity?

Accepted Answer

Direct phosphorylation of ADP by creatine phosphate: $$\mathrm{CP + ADP \rightarrow Creatine + ATP}$$

Question 8

Which structure in the sarcomere anchors the thin filaments and marks the boundary between adjacent sarcomeres?

Accepted Answer

Z disc

Question 9

A patient with myasthenia gravis has antibodies against acetylcholine receptors. Which component of the neuromuscular junction is directly affected?

Accepted Answer

Junctional folds of the sarcolemma

Question 10

Which event directly triggers the release of calcium ions from the sarcoplasmic reticulum during muscle contraction?

Accepted Answer

Action potential propagation down the T tubules

Question 11

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

Accepted Answer

ATP is needed to detach myosin heads from actin filaments.

Question 12

Which of the following is a property of muscle tissue that allows it to respond to a stimulus?

Accepted Answer

Excitability

Question 13

A marathon runner relies primarily on which ATP-generating pathway during prolonged exercise?

Accepted Answer

Aerobic respiration

Question 14

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

Accepted Answer

Isotonic contractions change muscle length, while isometric contractions do not.

Question 15

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

Accepted Answer

Action potential travels down T tubules $$\rightarrow$$ calcium release from SR $$\rightarrow$$ calcium binds to troponin $$\rightarrow$$ cross-bridge formation

Question 16

Which of the following is a function of the motor unit in skeletal muscle?

Accepted Answer

It consists of a single motor neuron and all the muscle fibers it innervates, allowing graded force production.

Question 17

Which of the following would most likely occur if the muscular system could not maintain homeostasis?

Accepted Answer

Body temperature regulation would be impaired, leading to hypothermia.

Question 18

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

Accepted Answer

Troponin binds calcium ions, causing tropomyosin to move and expose myosin-binding sites on actin.

Question 19

Which of the following is the correct definition of the term 'origin' in relation to muscle attachment?

Accepted Answer

The origin is the fixed attachment point of a muscle to bone, typically proximal to the insertion.

Muscles and Muscle Tissue: Structure, Function, and Physiology

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