Muscle Structure and Function

Question 2

What connective tissue surrounds individual muscle fibers?

Answer 2

Endomysium

Question 3

What are multiple muscle fibers bundled together called?

Answer 3

Fascicles

Question 4

What connective tissue surrounds each fascicle?

Answer 4

Perimysium

Question 5

What connective tissue surrounds the entire muscle (all fascicles)?

Answer 5

Epimysium

Question 6

What structure binds several muscles into functional groups?

Answer 6

Deep fascia

Question 7

What is the purpose of connective tissue layers in muscles?

Answer 7

They provide structure, protection, and transmit force from muscle to tendon.

Question 8

What are the dark bands in skeletal muscle called?

Answer 8

A bands

Question 9

What are the light bands in skeletal muscle called?

Answer 9

I bands

Question 10

What is found in the center of the A band and contains only thick filaments?

Answer 10

H band

Question 11

What structure is located in the middle of the H band?

Answer 11

M line

Question 12

What structure marks the boundaries of a sarcomere?

Answer 12

Z disc (or Z line)

Question 13

Where is the Z disc located?

Answer 13

In the center of the I band

Question 14

What protein provides elasticity and stabilizes thick filaments?

Answer 14

Titin

Question 15

What is the functional unit of muscle contraction?

Answer 15

The sarcomere (from one Z disc to the next)

Question 16

What are the two forms of actin?

Answer 16

G-actin (globular) and F-actin (filamentous)

Question 17

What does G-actin form when polymerized?

Answer 17

F-actin, the helical filament of the thin filament

Question 18

What protein covers actin’s active sites in a relaxed muscle?

Answer 18

Tropomyosin

Question 19

What protein complex binds calcium and moves tropomyosin?

Answer 19

Troponin

Question 20

What is the long tail portion of the myosin molecule called?

Answer 20

The rod region

Question 21

What part of myosin forms cross-bridges with actin?

Answer 21

The globular heads

Question 22

What enzyme activity is found in the myosin heads?

Answer 22

ATPase activity (for energy during contraction)

Question 23

What happens when calcium binds to troponin?

Answer 23

Tropomyosin shifts, exposing actin’s binding sites for myosin attachment.

Question 24

What is the mechanism of muscle contraction called?

Answer 24

The sliding filament mechanism