Muskuloskeletal

Question 1

Which of the following compounds binds to actin to initiate muscle contraction?

a) Calcium
b) Creatinine kinase
c) Myosin
d) Troponin

Answer 1

c) Myosin

Question 2

Polysaccharide storage myopathy type I is associated with a defect in which of the following genes?

a) Glycogen branching enzyme
b) Glycogen synthase 1
c) Ryanodine receptor 1
d) Sodium channel α-subunit

Answer 2

b) Glycogen synthase 1

Question 3

Which of the following statements regarding the pathophysiology of malignant hyperthermia is TRUE?

a) A deficiency in acetylcholinesterase results in prolonged muscle contraction.
b) A genetic mutation in the calcium channel gene results in aberrations in the release of calcium from the sarcoplasmic reticulum.
c) An inability to store and mobilize glycogen results in an inability for tissues to function.
d) An increase in membrane sodium conductance occurs due to a defect in voltage dependent sodium channels which fail to inactivate.
e) Reduced activity of mitochondrial enzyme Complex 1 results in severe exercise intolerance and lactic acidemia.

Answer 3

b) A genetic mutation in the calcium channel gene results in aberrations in the release of calcium from the sarcoplasmic reticulum.