Infrastructure of Skeletal Muscle

Question 1

All muscle has what property?

Answer 1

contractility

Question 2

3 types of muscle fibers

Answer 2

• smooth
• cardiac
• skeletal

Question 3

Skeletal muscle fibers are mononucleated or multinucleated?

Answer 3

multinucleated

Question 4

The “I” in ‘I-bands’ stands for _______

Answer 4

isotropic

Question 5

The “A” in ‘A-bands’ stands for _______

Answer 5

anisotropic

Question 6

the _____ anchors the thin filaments of sarcomeres

Answer 6

Z-band

Question 7

the ______ anchors adjacent thick filaments

Answer 7

M-line

Question 8

________ is the section of the sarcomere with only thick filaments, there is no overlap with the thin filaments

Answer 8

H-band

Question 9

__________: the space between adjacent myofibrils

Answer 9

intermyofibrillar space

Question 10

_________: anchor thin filaments

Answer 10

Z-lines

Question 11

Z-lines are composed of _______ and _______

Answer 11

• (alpha)-actin

- Z-line filaments

Question 12

M-lines are composed of _________ and ________

Answer 12

• M-line filaments

- creatine kinase

Question 13

the M-line contains contain ____% of the total creatine kinase for the muscle fiber

Answer 13

10%

Question 14

4 things contained within the intermyofibrillar space

Answer 14

• sarcoplasmic reticulum
• mitochondria
• glycogen
• lipids

Question 15

3 intermediate anchoring filaments in the sarcomere

Answer 15

• vinculin
• desmin
• vimentin

Question 16

_________: large springy globular protein that anchors M-bands and imparts a portion of the passive elastic component of muscle

Answer 16

titin

Question 17

_________ is the largest protein yet discovered and is the third most abundant muscle protein, comprising approximately 10% of the combined muscle protein content

Answer 17

titin

Question 18

the elasticity of titan helps to what?

Answer 18

restore the stretched sarcomere (muscle) back to its correct length

Question 19

Ratio of thick to thin filaments in muscle

Answer 19

6 thin: 1 thick

Question 20

the sarcolemma is attached to the endomysium via _______________ and invades the cell via the _____________

Answer 20

• connective tissue reticular fibers

- T-tubule system

Question 21

_________: cytoskeletal protein located on the inner surface of the sarcolemma which is involved in structural integrity - anchoring of actin and may help in regulation of membrane proteins (ex. ion channels)

Answer 21

dystrophin

Question 22

What is the function of dystrophin?

Answer 22

the transmission of force to the extracellular matrix

Question 23

________: an X-linked disease where dystrophin is absent and muscle cells are unable to survive

Answer 23

muscular dystrophy

Question 24

What symptom of muscular dystrophy would show up in a blood analysis?

Answer 24

creatine kinase levels as much as 10 x the normal level

Question 25

What would a severely abnormally high level of creatine kinase potentially indicate?

Answer 25

Muscular dystrophy

Question 26

3 fields of research for a potential cure for muscular dystrophy

Answer 26

- stem cell research - myostatin inhibitor trials - follistatin activator trials

Question 27

the "Belgian Blue" is a cattle breed that exhibits what genetic abnormality?

Answer 27

myostatin knockout

Question 28

The sarcolemma-T-tubule interconnection triad is located where?

Answer 28

at the A-I junction of sarcomeres

Question 29

Ca++ is released along the ____________ and reuptake occurs at the __________

Answer 29

- A-I junction | - M-line

Question 30

Ca++ reuptake is regulated by __________

Answer 30

intracellular Ca++ levels

Question 31

intracellular ↑ in Ca++ stimulate ___________ on the sarcoplasmic reticulum

Answer 31

ATP-driven Ca++ pump

Question 32

the Ca++/ATP pump moves ___ Ca++ ions for every molecule of ATP consumed

Answer 32

2

Question 33

Ca++ pumps are concentrated along the _____________ of the sarcoplasmic reticulum

Answer 33

longitudinal sarcotubules

Question 34

Ca++ binding within the sarcoplasmic reticulum is achieved by ___________

Answer 34

calsequestrin

Question 35

According to the Sliding Filament Hypothesis, which sections of the muscle cell will decrease in length with contraction?

Answer 35

- sarcomere - I band - H band

Question 36

According to the Sliding Filament Hypothesis, which sections of the muscle cell will have no change in length with contraction?

Answer 36

- A bands | - M bands