Question 1 . \"Hypoxemia triggers a ___ feedback mechanism, which leads to a(n)_

Question

Question 1. "Hypoxemia triggers a ___ feedback mechanism, which leads to a(n)___."

a- negative / decrease in RBC count

b- negative / increase in RBC count

c- positive / increase in RBC count

d- positive / decrease in RBC count

Question 2. These will all increase cardiac output except an___

a-increased activity of the respiratory pump

b-increased stimulation of the nodes

c-increased blood pressure in the aorta

d-increased venous return

Question 1. "Hypoxemia triggers a ___ feedback mechanism, which leads to a(n)___."

a- negative / decrease in RBC count

b- negative / increase in RBC count

c- positive / increase in RBC count

d- positive / decrease in RBC count

Explanation / Answer

Hypoxemia is the term which is used to describe extremely low levels of oxygen in the blood. Any problem in the respiratory or the circulatory system that alters the volume or rate of oxygen entering the lungs might result in hypoxemia.

1) When there is a sudden decrease in the amount of oxygen in the blood, it is detected by kidneys which in turn secrete the glycoprotein, Erythropoietin (EPO). EPO then stimulates the bone marrow to produce more red blood cells.

Therefore, the answer is (b) negative/ increase in RBC count

2) Cardiac output refers to the amount of blood that is pumped by the heart in one minute. Cardiac output can also be described as the product of heart rate and the stroke volume. An increase in the activity of the respiratory pump, stimulation of nodes and venous return has a positive effect on the stroke volume, which in turn increases the cardiac output. However an increase in the aortic blood pressure will result in an increase in afterload which will decrease the cardiac output.

Therefore, the correct answer is (c) increased blood pressure in the aorta

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