Skeletal Muscle (anatomy)

Question 1

What is the plasma membrane of the muscle fiber called?

Answer 1

Sarcollema

Question 2

What is the internal environment of the muscle fiber called?

Answer 2

Sarcoplasm

Question 3

Are muscle fibers multi-nucleited?

Answer 3

Yes

Question 4

What are the contents of the sarcoplasm?

Answer 4

• myofibrils (most important)

- Mitochondria

Question 5

What are myofibrils composed of?

Answer 5

Contractual proteins

- troponin
- actin
- tropomyosin
- myosin

Question 6

What are thick filaments of the sarcomere composed of?

Answer 6

Myosin

Question 7

Myofibrils are organized into what structure?

Answer 7

Sarcomere

Question 8

What is the structure of a myosin molecule composed of?

Answer 8

• myosin heads

- myosin tail

Question 9

What are thin filaments compose of? What is the majority of it made of?

Answer 9

• actin (majority)
• troponin
• tropomyosin

Question 10

In the sarcomere, what is always found in the center?

Answer 10

-Thick filament

Question 11

Sarcomere is defined by what structure?

Answer 11

-distance between Z disk

Question 12

How are the filaments arranged in a sarcomere?

Answer 12

Thin, thick, thin, thick

Question 13

How are the I, A bands organized in the myofibrils?

Answer 13

Question 14

What happens in the zone of overlap?

Answer 14

• Where thin (actin molecule) and thick (myosin head) filaments overlap
• this is how contraction occurs

Question 15

What covers/surrounds the myofibril?

Answer 15

• sarcoplasmic reticulum (smooth ER)

- stores calcium ions

Question 16

What does the sarcoplasmic reticulum store?

Answer 16

-calcium ions