Muscle Physiology

Question 1

withn myofibers are what?

Answer 1

myofibrils

Question 2

myofibrils contain what?

Answer 2

myofilaments

Question 3

myofilaments contain what?

Answer 3

thick and thin filaments

Question 4

what is the smallest contractile unit of skeletal muscle?

Answer 4

sarcomere

Question 5

what is the invagination of the sarcolemma called?

Answer 5

T tubules

Question 6

what are the three things in thin filaments?

Answer 6

actin, tropomyosin

troponin

Question 7

when Ca binds troponin what happens to thin filaments?

Answer 7

it removes the tropomyosin that is guarding the thick filament binding site on the thin filament

Question 8

what type of receptor is present at the peaks in the Neuromuscular junction?

Answer 8

nicotinic acetylcholine receptor channels

Question 9

in a muscle AP, what are the important voltage gated channels called?

Answer 9

Calcium channels named L type or DHP receptors

Question 10

what are L type voltage gated calcium channels linked to in skeletal muscle?

Answer 10

ryanodine receptors

Question 11

what do ryanodine receptors release? from where?

Answer 11

release calcium from the sarcoplasmic reticulum

Question 12

when myosin is fused to actin what must bind to release it??

Answer 12

ATP

Question 13

after ATP binds myosin what happens?

Answer 13

releases from actin and ATP can be hydrolyzed

Question 14

once ATP is hydrolyzed into ADP and P what happens?

Answer 14

myosin head moves forward out of cocked position

Question 15

once myosin in uncocked position what happens?

Answer 15

will bind the actin again

Question 16

once myosin is bound to actin in uncocked position what happens?

Answer 16

ADP releases and myosin cocks back moving the filaments

Question 17

what is the H zone in sarcomere?

Answer 17

only thick filaments

Question 18

what is the A band in sarcomere?

Answer 18

length of the whole thick filament, including overlap with thin

Question 19

what is the I band in sarcomere?

Answer 19

only thin filament

Question 20

what three zones shorten in a sarcomere with contractions?

Answer 20

HIZ

Question 21

explain how tetanus occurs

Answer 21

muscle stimulated repeatedly so insufficient time for Ca to go back into the SR and you get sustained contraction

Question 22

what are the three skeletal muscle fiber types

Answer 22

type 1
type2A
type2B

Question 23

what color does type 1 muscle fiber appear?

Answer 23

red

Question 24

what color does type 2A muscle fiber appear?

Answer 24

grey

Question 25

what color does type 2B muscle fiber appear?

Answer 25

white

Question 26

why does type 1 muscle fiber appear red?

Answer 26

presence of myoglobin

Question 27

what does type 1 muscle fiber use for energy?

Answer 27

oxidative phosphorylation

Question 28

what are type 1 muscle fibers good for?

Answer 28

sustained contraction

Question 29

what muscle fiber type has lots of mitochondria?

Answer 29

type 1

Question 30

what do type 2B muscle fibers use for energy?

Answer 30

lots of glycolysis…anaerobic glycolysis

Question 31

are type 2B fast or slow twitch muscle fibers?

Answer 31

fast twitch

Question 32

what movements are type 2B fibers good for?

Answer 32

explosive movement

Question 33

why do type 2B muscle fibers appear white?

Answer 33

because they lack myoglobin

Question 34

what is type 2A muscle fiber?

Answer 34

a mix between type 1 and 2B

Question 35

what does type 2A muscle fiber use for energy?

Answer 35

glycogen and myoglobin for oxidative phosphorylation

Question 36

type 2A muscle fibers are more slow or fast twitch muscles

Answer 36

fast

Question 37

what are type 2A muscle fibers better at avoiding compared to type 2B fibers?

Answer 37

fatigue

Question 38

can fibers change type with exercise?

Answer 38

yes