Q: Arrange the following structures from superficial to deep: epimysium, perimysium, endomysium, myofibril, myofilament.

$$\text{Epimysium} \rightarrow \text{Perimysium} \rightarrow \text{Endomysium} \rightarrow \text{Myofibril} \rightarrow \text{Myofilament}$$

Question 1

Which property of muscle tissue allows it to return to its original shape after being stretched or contracted?

Accepted Answer

Elasticity

Question 2

A patient is unable to voluntarily move their heart muscle but can flex their biceps at will. Which statement best explains this phenomenon?

Accepted Answer

Cardiac muscle is involuntary, while skeletal muscle is voluntary.

Question 3

You are examining a muscle tissue under a microscope and observe no striations. Which type of muscle could this be?

Accepted Answer

Smooth muscle

Question 4

Which connective tissue layer directly surrounds individual muscle fibers?

Accepted Answer

Endomysium

Question 5

Arrange the following structures from superficial to deep: epimysium, perimysium, endomysium, myofibril, myofilament.

Accepted Answer

$$	ext{Epimysium} ightarrow 	ext{Perimysium} ightarrow 	ext{Endomysium} ightarrow 	ext{Myofibril} ightarrow 	ext{Myofilament}$$

Question 6

During muscle contraction, which structure shortens?

Accepted Answer

Sarcomere

Question 7

Which protein blocks the myosin binding sites on actin in a relaxed muscle?

Accepted Answer

Tropomyosin

Question 8

A rare condition causes myosin to clump in skeletal muscle. What would you expect to see in the sarcomere?

Accepted Answer

The thick filament would form protein clumps.

Question 9

Which region of the sarcomere contains only thin filaments and shortens during contraction?

Accepted Answer

I Band

Question 10

What is the primary role of the sarcoplasmic reticulum in muscle contraction?

Accepted Answer

It stores and releases calcium ions.

Question 11

Which ion is responsible for depolarization during an action potential in muscle fibers?

Accepted Answer

Na+

Question 12

What would happen if acetylcholinesterase was inhibited at the neuromuscular junction?

Accepted Answer

Muscle would remain contracted due to continuous stimulation.

Question 13

Which step in the cross-bridge cycle is directly powered by ATP hydrolysis?

Accepted Answer

Cocking of the myosin head

Question 14

If a muscle cell completely runs out of ATP during contraction, what is the immediate consequence?

Accepted Answer

After the power stroke, the myosin would remain bound to the actin.

Question 15

Which of the following is NOT found in the A band of a sarcomere?

Accepted Answer

Z Disc

Question 16

Which event directly triggers the release of acetylcholine from the axon terminal at the neuromuscular junction?

Accepted Answer

Influx of Ca+2 into the axon terminal

Question 17

Which structure in a muscle fiber has the greatest total surface area and is responsible for storing calcium?

Accepted Answer

Sarcoplasmic reticulum

Question 18

Which protein is responsible for the elasticity of the sarcomere?

Accepted Answer

Titin

Question 19

Which of the following best describes the sliding filament theory?

Accepted Answer

Actin and myosin filaments slide past each other, shortening the sarcomere.

Question 20

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

Accepted Answer

Action potential travels down sarcolemma → Ca+2 released from sarcoplasmic reticulum → Ca+2 binds troponin → Tropomyosin moves → Myosin binding sites exposed

Muscle Tissue and Physiology: Structured Study Notes

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