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

$$\mathrm{ATP} + \mathrm{H}_2\mathrm{O} \rightarrow \mathrm{ADP} + \mathrm{P}_i + \text{energy}$$

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

Immobility

Question 3

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

Accepted Answer

It is the site 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

Which receptor on the muscle cell membrane binds the neurotransmitter released at the NMJ?

Accepted Answer

Nicotinic acetylcholine receptor

Question 9

During muscle contraction, what is the sequence of events from action potential to sarcomere shortening?

Accepted Answer

Action potential → calcium release → troponin activation → tropomyosin moves → myosin binds actin → sarcomere shortens

Question 10

Which molecule must bind to myosin to allow it to break cross-bridges during muscle relaxation?

Accepted Answer

ATP

Question 11

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

Accepted Answer

Calcium ions must be pumped back into the sarcoplasmic reticulum

Question 12

A patient is unable to move their muscles due to a defect in acetylcholine receptors at the NMJ. Which process is most directly affected?

Accepted Answer

Generation of action potential in the muscle cell

Question 13

If the sarcoplasmic reticulum fails to reabsorb calcium ions after contraction, what is the most likely consequence?

Accepted Answer

Muscle remains contracted and cannot relax

Question 14

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

Accepted Answer

$$\mathrm{ATP} + \mathrm{H}_2\mathrm{O} ightarrow \mathrm{ADP} + \mathrm{P}_i + 	ext{energy}$$

Question 15

Which of the following best explains why calcium ions are essential for muscle contraction?

Accepted Answer

They bind to troponin, causing tropomyosin to move and expose myosin binding sites on actin

Question 16

A patient with myasthenia gravis has antibodies against acetylcholine receptors. Which symptom would you expect?

Accepted Answer

Muscle weakness due to impaired transmission at the NMJ

Question 17

Which step in muscle contraction directly requires ATP?

Accepted Answer

Detachment of myosin from actin after the power stroke

Question 18

Which of the following is the correct sequence for the events at the NMJ leading to muscle contraction?

Accepted Answer

Action potential arrives at axon terminal → acetylcholine released → acetylcholine binds to receptors on muscle fiber → muscle action potential generated

Question 19

Which of the following would most likely result from a mutation that prevents tropomyosin from moving off the myosin binding sites on actin?

Accepted Answer

Muscle contraction would be inhibited

Muscle Tissue and Neuromuscular Junction: Study Notes for Anatomy & Physiology

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