MSK 2 PHYSIOLOGY

Main source of calcium in smooth muscle contraction is from:

• Extracellular fluid

• Sarcoplasmic reticulum

• Intracellular fluid

• Transverse tubules

During Latch mechanism for smooth muscle contraction, Calcium binds with:

• Troponin

• Calseqeustrin

• Calmodulin

• Tropomyosin

During relaxation of smooth muscle, decreased calcium sensitivity can be attributed to which of the following?

• Actin

• ATP

• Calmodulin

• Myosin Phosphate

Which of the following describes a physiological difference between contraction of smooth muscle compared to contraction of skeletal muscle?

• Calcium independent

• Requires more energy

• Force of contraction is more

• Possess pacemaker potential

Regarding membrane potential in smooth muscle, which of the following does NOT generate action potential.

• Cardiac Muscle

• Multi unit smooth muscle in iris of eye

• Single units in respiratory tract

• Single units in GIT (Gastro Intestinal Tract)

Latch mechanism in muscles maintain the tone in the blood vessels and keep them patent. The tone is due to 

• Increased consumption of energy

• Decreased duration of contraction

• Decreased consumption of energy with prolonged contraction

• Alternate relaxation and contraction

In the contraction of GI smooth muscle, which of the following events occur after binding of calcium to calmodulin?

• Depolarization of sarcolemma membrane

• Increased myosin light chain kinase

• Increased intracellular Ca concentration

• Opening of ligand gated Ca channels