Please select the best option for each part. Part A. Which of the following woul

Question

Please select the best option for each part.

Part A. Which of the following would be extremely hard to measure and probably unethical in DMD patients?

a) Serum creatine kinase activity.

b) Eccentric contraction-induced force drop.

c) 6 minute walk.

d) The percentage of centrally-nucleated fibers.

e) None of the above.

Part B. Skeletal excitation-contraction coupling requires these events (select the BEST answer)?

a) activated dihydropyridine receptor (DHPR) stops inhibiting the ryanodine receptor

b) activated DHPR physically activates the ryanodine receptor

c) activated RyR1 permits large SR Ca2+ release

d) RyR1 uncoupled from DHPR are activated by Ca2+

e) all of the above

Part C.The main membrane protein inhibitor of SERCA1a in fast-twitch skeletal muscle is:

a) phospholamban (PLB)

b) sarcolipin

c) calmodulin

d) DWORF

e) PKA

Explanation / Answer

In part A all the option are correct and the correct statenent is E none of the above

in part B best answer is option B- activated DHPR physically activates the ryanodine receptor

beacause DHPR receptor present over the T tubule in sarcolemma ( membrane of muscle) so when depolarisation come at muscle endplate then it activate these receptor which are voltage sensitive receptor

Further,

they physically interact with the sarcoplasmic reticulum present on both side of T tubule known as terminal cisterns(L-tubule).

these L-tubule after physical interaction releases calsium which cause excitation contraction coupling and muscle contraction

part C- correct answe is -A phospholamban

SERCA1a moves Calsium inside the sarcoplasmic reticulumn(L-tubule)

can be controlled by the protein phospholamban (PLB). SERCA1a is not active when phospholamban attached with it.

with high -adr stimulation decreases the interaction between SERCA1a and Phospholamban by the phosphorylation of Phospholaban by protein kinase A.

PLB+ SERCA = rate of Ca2+ movement is decresed

AND

PLB- SERCA= Ca2+ movement increased.

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