Question 1

Which property of muscle tissue is most directly responsible for the ability to convert chemical energy into mechanical energy, as seen when flexing the arm in the first image?

Accepted Answer

Contractility

Question 2

A patient is able to voluntarily flex their biceps but cannot consciously slow their heart rate. Based on the types of muscle tissue, which statement best explains this observation?

Accepted Answer

The heart is composed of cardiac muscle, which is involuntary.

Question 3

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

Accepted Answer

Smooth muscle

Question 4

Which type of muscle cell is typically the largest in diameter and length?

Accepted Answer

Skeletal muscle cell

Question 5

In the context of marbling in beef (as shown in the image of Kobe beef), in which connective tissue layer would you expect to find the most intramuscular fat?

Accepted Answer

Epimysium and perimysium

Question 6

Which layer of connective tissue surrounds and separates individual muscle fibers?

Accepted Answer

Endomysium

Question 7

Arrange the following structures from superficial to deep in a skeletal muscle: epimysium, perimysium, fascicle, endomysium, myofibril, myofilament.

Accepted Answer

Epimysium → Perimysium → Fascicle → Endomysium → Myofibril → Myofilament

Question 8

The plasma membrane of a muscle fiber is called the ______ and it wraps bundles of ______.

Accepted Answer

Sarcolemma; myofibrils

Question 9

True or False: The smallest contractile unit of a muscle is the muscle cell.

Accepted Answer

False, the smallest contractile unit is the sarcomere.

Question 10

During a muscle contraction, which structure shortens?

Accepted Answer

Sarcomere

Question 11

Which protein is responsible for blocking the myosin binding sites on actin in a relaxed muscle?

Accepted Answer

Tropomyosin

Question 12

A rare congenital condition causes myosin to fold incorrectly, forming clumps in skeletal muscle. What would you expect to see in the sarcomere of an affected individual?

Accepted Answer

The thick filament would form protein clumps.

Question 13

Which region of the sarcomere is the same length as the actin filament?

Accepted Answer

From the edge of the H zone to the Z disc

Question 14

During an action potential in a muscle fiber, which ion moves into the cell to cause depolarization, and which ion moves out to cause repolarization?

Accepted Answer

Na+ in, K+ out

Question 15

What is the role of calcium ions at the neuromuscular junction?

Accepted Answer

Calcium entering the axon terminal triggers the release of acetylcholine into the synaptic cleft.

Question 16

Which part of the cross-bridge cycle is called the power stroke?

Accepted Answer

Myosin pulling the actin

Question 17

If a muscle completely ran out of ATP during contraction, what would happen?

Accepted Answer

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

Question 18

Which protein contributes to the structural integrity of the sarcomere by providing elasticity?

Accepted Answer

Titin

Question 19

Which of the following best describes the sequence of events in excitation-contraction coupling?

Accepted Answer

Action potential travels down sarcolemma and T-tubules → Voltage-gated Ca2+ channels open in sarcoplasmic reticulum → Ca2+ binds to troponin → Troponin moves tropomyosin → Myosin binding sites on actin are exposed

Muscles and Muscle Tissue: Structure, Function, and Contraction

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