Question

What happens to blood when it is pumped into the thin-walled blood vessels of the lungs?
A. Platelets are exchanged for plasma.
B. Carbon dioxide is replaced with oxygen.
C. Blood fills the lungs and causes coughing.
D. Nothing -- the lungs are just a place blood goes through on its way back to the heart.

Answer 1

Answer:

Correct option is

B

Carbon dioxide is replaced with oxygen

When blood is pumped into the thin-walled blood vessels of the lungs, carbon dioxide is replaced with oxygen. The pulmonary arteries carry the blood that has been pumped from the right side of the heart to the lungs for the oxygenation which is returned back to the left atrium by the pulmonary veins.

So, the correct answer is option B

Answer 2

When blood is pumped into the thin-walled blood vessels of the lungs B. Carbon dioxide is replaced with oxygen.

• Replacement of carbon dioxide with oxygen occurs at alveoli.
• Pressure gradient or concentration gradient is responsible for the simple diffusion by which the gaseous exchange is facilitated.
• The partial pressure of oxygen is less in deoxygenated blood in comparison to the alveoli. Hence, the oxygen diffuses from the alveoli towards the blood.
• While partial pressure of carbon dioxide is more in deoxygenated blood in comparison to the alveoli, hence it moves from blood to alveoli.