1. Phosphorylation of phospholamban by PKA increases the activity of SERCA2a. Wh

Question

1. Phosphorylation of phospholamban by PKA increases the activity of SERCA2a. What is the result if heart rate stays the same and the level of phospholamban phosphorylation increases?

a) SR Ca concentration decreases, amount of SR Ca released decreases, and developed force decreases

b) SR Ca concentration decreases, amount of SR Ca released stays same, and developed force decreases

c) SR Ca concentration increases, amount of SR Ca released stays same, and developed force stays the same

d) SR Ca concentration increases, amount of SR Ca released decreases, and developed force stays the same

e) SR Ca concentration increases, amount of SR Ca released increases, and developed force increases

2. Which of the following is not true for large arteries

a) they behave as low-pass filter for the pressure pulse

b) they hold more than 1/2 the total blood volume

c) they stretch considerably during systole

d) the act to maintain pressure during diastole

3. The major force favoring fluid filtration from the capillaries into the interstitial fluid

a) capillary hydrostatic pressure

b) capillary oncotic pressure

c) interstitial fluid hydrostatic pressure

d) interstitial fluid oncotic pressure

Explanation / Answer

1.Option E.

When phospholamban is phosphorylated, it fails to deactivate serca2a. So the serca2a conc. increases and it results in excess calcium release which reduces the contractility and rate of muscle relaxation of heart which increases the force

2.option B.

Arteries do not hold half of the blood volume.

3.C. Interstitial fluid hydrostatic pressure

The Interstitial fluid hydrostatic pressure exerts pressure on the capillaries and the large proteins cannot cross the capillaries but the fluid crosses it and reaches the Interstitial space.

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