Skeletal Muscle

Question 1

motor unit

Answer 1

motor neuron and all the fibers it innervates

Question 2

what is the synapse of a motor neuron called?

Answer 2

end plate

Question 3

T/F you will always get an action potential in skeletal muscle

Answer 3

true

Question 4

what is the potential change in the membrane of a skeletal muscle called?

Answer 4

end plate potential (EPP)

Question 5

describe action potential movement in muscle cell

Answer 5

flows down plasma membrane (releases internal stores of calcium)
down t- tubules
activates DHPRs
makes physical contact with RyR to release calcium from sarcoplasmic reticulum

Question 6

where is the main storage of calcium in muscle cells?

Answer 6

sarcoplasmic reticulum

Question 7

CICR

Answer 7

calcium induced calcium release

positive feedback where calcium goes on to activate more RyR proteins

Question 8

DHPR

Answer 8

modified type of voltage gated calcium channel

Question 9

how does calcium induce muscle contraction

Answer 9

via interaction of myosin and actin

Question 10

titin

Answer 10

provides elasticity and stabilizes myosin

Question 11

what determines if the muscle is fast or slow twitch

Answer 11

ATP splitting by the regulatory light chain of the myosin

Question 12

why are tropomyosin and troponin important for skeletal muscle contraction

Answer 12

Calcium binds TnC and shifts the troponin complex further into the groove to unmask the myosin binding site

Question 13

troponin complex

Answer 13

TnI
TnC
TnT
tropomyosin
working together to hid the myosin binding site on actin

Question 14

describe hydrolysis of ATP and the powerstroke

Answer 14

atp binds and causes dissociation of actin myosin complex
atp hydrolyzed and returns to resting conformation (cocked)
cross bridge forms
P is released causing conformational change and powerstroke
adp released (attached state)

Question 15

Does A band increase, decrease, same

Answer 15

same

Question 16

Does H band increase, decrease, same

Answer 16

decrease

Question 17

Does I band increase, decrease, same

Answer 17

decrease

Question 18

what happens to band overlap if you stretch a muscle too much

Answer 18

no overlap of actin and myosin

Question 19

what enzyme converts choline and acetyl coa into Ach

Answer 19

choline acetyltransferase

Question 20

What are the ways to reuptake calcium?

Answer 20

NCX (from inside cell to outside)
SERCA (from cytosol to SR)
calsequestrin (calcium binding buffer)

Question 21

how to increase force of contraction

Answer 21

fiber summation (more motor units)
frequency summation (more stimuli to one fiber)

Question 22

rhabdomyolysis

Answer 22

damage/death of muscle fibers and release of contents into bloodstream

Question 23

blood serum Rhabdomyolysis

Answer 23

high creatine kinase
hyperkalemia
high myoglobin (kidney damage)
hypocalcemia
lactic/organic acids

Question 24

rhabdomyolysis symptoms

Answer 24

reddish/brown urine

muscle pain/fatigue

Question 25

myasthenia gravis

Answer 25

autoimmune disease
antibody to Ach NR
weakening of skeletal muscle