Question

Which one of the following graphs best describe the blood pressure (BP) change when blood moves from the aorta to capillaries?

• A. A
• B. B
• C. C
• D. D

Answer 1

The correct option is A A

The blood pressure change is inversely proportional to the diameter of the blood vessel. The blood vessel with large diameter has less blood contacting the vessel wall. Hence, there is lower friction and lower resistance. This subsequently results in increased flow. The blood vessel with small diameter has more of the blood that contacts the vessel wall. Hence, there is more friction resistance. This results in the subsequent decrease in the flow. The blood pressure in the aorta is much higher than that of the capillaries. This is because although the diameter of an individual capillary is narrower than the diameter of the aorta, the diameter of combined capillaries is far greater than the diameter of an aorta. Hence, the blood pressure is actually lower in capillaries that that in the aorta.

Thus, the correct answer is option A.