$$ATP \rightarrow ADP + P_i + \text{energy}$$

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 of the following is NOT a characteristic of muscle tissue?

Accepted Answer

Secretion

Question 3

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

Accepted Answer

It is the functional unit where actin and myosin interact to produce contraction

Question 4

Which of the following correctly lists the proteins involved in muscle contraction and their roles?

Accepted Answer

Troponin binds calcium, tropomyosin blocks myosin binding sites, actin forms thin filaments, myosin forms thick filaments

Question 5

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

Accepted Answer

Motor neuron

Question 6

At the NMJ, which two cell types synapse together?

Accepted Answer

Motor neuron and muscle fiber

Question 7

Which neurotransmitter is released at the NMJ to initiate muscle contraction?

Accepted Answer

Acetylcholine

Question 8

What type of receptor is required on the muscle cell membrane to respond to the neurotransmitter released at the NMJ?

Accepted Answer

Nicotinic acetylcholine receptor

Question 9

During muscle contraction, which ion is released from the sarcoplasmic reticulum to trigger the interaction between actin and myosin?

Accepted Answer

Calcium ($$Ca^{2+})$$

Question 10

Which of the following steps occurs FIRST in the process of muscle contraction after the action potential reaches the NMJ?

Accepted Answer

Binding of acetylcholine to its receptor on the muscle cell membrane

Question 11

Which molecule is required to bind to myosin in order to break cross-bridges during muscle relaxation?

Accepted Answer

ATP

Question 12

Which event must occur for muscle relaxation to take place after contraction?

Accepted Answer

Calcium ions are pumped back into the sarcoplasmic reticulum

Question 13

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

Accepted Answer

Muscle contraction will be inhibited

Question 14

Which of the following best explains the sliding filament theory of muscle contraction?

Accepted Answer

Actin filaments slide past myosin filaments, shortening the sarcomere

Question 15

If a muscle cell is unable to produce ATP, which step in the contraction cycle will be directly affected?

Accepted Answer

Detachment of myosin from actin (cross-bridge release)

Question 16

Which equation best represents the process of ATP hydrolysis during muscle contraction?

Accepted Answer

$$ATP ightarrow ADP + P_i + 	ext{energy}$$

Question 17

During a muscle contraction, which of the following sequences correctly describes the flow of events from neural stimulation to contraction?

Accepted Answer

Action potential in motor neuron → release of acetylcholine → depolarization of muscle cell membrane → release of calcium → cross-bridge formation

Question 18

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

Accepted Answer

Muscle weakness

Question 19

Which of the following is a direct result of calcium binding to troponin during muscle contraction?

Accepted Answer

Tropomyosin moves away from myosin binding sites on actin

Question 20

Which process is responsible for terminating the action of acetylcholine at the NMJ after muscle contraction?

Accepted Answer

Acetylcholinesterase breaks down acetylcholine in the synaptic cleft

Muscle Tissue and Neuromuscular Junction: Structure, Function, and Physiology

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