Q: Which of the following equations best represents the relationship between the number of myosin molecules ($$N_{myosin}) $$and the force generated ($$F) in a $$muscle fiber, assuming each myosin head generates a force $$f_{head}$$?

$$F = N_{myosin} \times f_{head}$$

Question 1

Which type of muscle tissue is responsible for voluntary movement by pulling on bones, and what is its primary function in the human body?

Accepted Answer

Skeletal muscle; producing body movement

Question 2

A patient suffers an injury that damages the connective tissue surrounding individual muscle fibers. Which structure is most likely affected?

Accepted Answer

Endomysium

Question 3

During muscle contraction, which band in the sarcomere shortens, and what is the underlying mechanism?

Accepted Answer

I band; increased overlap between thick and thin filaments

Question 4

Which protein prevents myosin from binding to actin in a resting muscle, and how is this inhibition removed during contraction?

Accepted Answer

Tropomyosin; by calcium binding to troponin

Question 5

If the sarcoplasmic reticulum (SR) fails to pump calcium ions ($$\mathrm{Ca$$^{2+}$$}) $$from the cytosol, what is the most likely consequence for muscle contraction?

Accepted Answer

Muscle contraction will be prolonged due to sustained high cytosolic $$\mathrm{Ca$$^{2+}$$}.$$

Question 6

Which structure is a bundle of muscle fibers, and what connective tissue surrounds it?

Accepted Answer

Muscle fascicle; perimysium

Question 7

A muscle fiber contains hundreds to thousands of myofibrils. What is the main function of these myofibrils?

Accepted Answer

Generate force through the interaction of actin and myosin

Question 8

Which of the following best describes the role of the transverse tubules (T-tubules) in skeletal muscle fibers?

Accepted Answer

They conduct action potentials deep into the muscle fiber.

Question 9

A mutation causes the Z line to fail to anchor thin filaments. What is the most likely effect on muscle contraction?

Accepted Answer

Sarcomeres will lose structural integrity, reducing force generation.

Question 10

Which of the following equations best represents the relationship between the number of myosin molecules ($$N_{myosin}) $$and the force generated ($$F) in a $$muscle fiber, assuming each myosin head generates a force $$f_{head}$$?

Accepted Answer

$$F = N_{myosin} 	imes f_{head}$$

Question 11

Which connective tissue layer directly surrounds the entire muscle and is composed of dense collagen fibers?

Accepted Answer

Epimysium

Question 12

A patient with a genetic defect in titin protein would most likely experience which of the following symptoms?

Accepted Answer

Reduced elasticity and stability of sarcomeres

Question 13

Which of the following statements about muscle fiber nuclei and mitochondria is correct?

Accepted Answer

Muscle fibers contain many nuclei and many mitochondria.

Question 14

Which protein acts as a 'string' stabilizing the structure of F-actin in thin filaments?

Accepted Answer

Nebulin

Question 15

During development, which cells fuse to form long, multinucleate muscle fibers, and what is the name of the cells that remain in the endomysium to aid in repair?

Accepted Answer

Myoblasts; myosatellite cells

Question 16

Which of the following best explains why the interior of the sarcolemma is more negative than the external environment?

Accepted Answer

Due to selective permeability of the sarcolemma

Question 17

Which of the following is TRUE regarding the function of skeletal muscle in maintaining body temperature?

Accepted Answer

Muscle contraction generates heat as a byproduct, helping regulate temperature.

Question 18

Which of the following structures is formed when collagen fibers at the ends of muscles combine to form a bundle or sheet?

Accepted Answer

Tendon/aponeurosis

Question 19

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

Accepted Answer

Troponin binds calcium ions, causing a conformational change that moves tropomyosin away from actin's active sites.

Question 20

If a muscle fiber has a sarcoplasmic reticulum $$\mathrm{Ca$$^{2+}$$}$$ concentration 40,000 times higher than the cytosol, what is the ratio of $$\mathrm{Ca$$^{2+}$$} in SR to $$cytosol?

Accepted Answer

$$40,000:1$$

Structure and Function of Muscle Tissue

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