Question 1

Which of the following best describes the hierarchical organization of muscle tissue from largest to smallest?

Accepted Answer

Muscle, muscle fiber, myofibril, myofilament

Question 2

Which protein must bind to myosin in order for cross-bridges to break during muscle contraction?

Accepted Answer

ATP

Question 3

What is the primary function of the sarcomere in muscle contraction?

Accepted Answer

It is the site where actin and myosin interact to produce force

Question 4

Which type of neuron stimulates skeletal muscle contraction at the neuromuscular junction (NMJ)?

Accepted Answer

Motor neuron

Question 5

At the NMJ, which neurotransmitter is released to initiate muscle contraction?

Accepted Answer

Acetylcholine

Question 6

Which of the following events must occur for muscle relaxation to take place?

Accepted Answer

Calcium ions must be actively pumped back into the sarcoplasmic reticulum

Question 7

Which of the following correctly lists the sequence of events in muscle contraction, starting from the arrival of the action potential at the NMJ?

Accepted Answer

Action potential arrives at NMJ → Acetylcholine released → Calcium released from sarcoplasmic reticulum → Myosin binds to actin → Sarcomere shortens

Question 8

Which of the following best explains the role of calcium ions in muscle contraction?

Accepted Answer

Calcium ions bind to troponin, exposing myosin-binding sites on actin

Question 9

Which of the following is NOT a characteristic of muscle tissue?

Accepted Answer

Secretion

Question 10

A patient is exposed to a toxin that blocks acetylcholine receptors at the NMJ. What is the most likely effect?

Accepted Answer

Muscle contraction will be inhibited

Question 11

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

Accepted Answer

ATP binds to myosin, causing it to detach from actin

Question 12

Which of the following formulas correctly represents the relationship between force ($$F$$), mass ($$m$$), and acceleration ($$a) in $$the context of muscle contraction?

Accepted Answer

$$F = m 	imes a$$

Question 13

During muscle contraction, which event directly follows the binding of calcium to troponin?

Accepted Answer

Tropomyosin shifts, exposing myosin-binding sites on actin

Question 14

Which of the following cell types synapse at the neuromuscular junction (NMJ)?

Accepted Answer

Motor neuron and muscle fiber

Question 15

A patient with myasthenia gravis has antibodies that block acetylcholine receptors at the NMJ. Which symptom would you expect?

Accepted Answer

Muscle weakness

Question 16

Which of the following is the correct sequence for the sliding filament theory of muscle contraction?

Accepted Answer

Myosin binds to actin → Power stroke → ATP binds to myosin → Myosin detaches from actin

Question 17

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

Accepted Answer

Troponin binds to calcium, causing tropomyosin to move and expose binding sites on actin

Question 18

Which of the following must occur for the muscle cell to return to its resting state after contraction?

Accepted Answer

Acetylcholine must be broken down by acetylcholinesterase

Question 19

Which of the following is a direct result of the action potential reaching the axon terminal of the motor neuron at the NMJ?

Accepted Answer

Release of acetylcholine into the synaptic cleft

Question 20

A muscle fiber is unable to contract even though acetylcholine is present at the NMJ. Which of the following is the most likely cause?

Accepted Answer

Failure of calcium release from the sarcoplasmic reticulum

Muscle Tissue and Neuromuscular Junction: Study Guide

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