Question

The blood pressure at your heart is approximately 100 mm Hg. As blood is pumped from the left ventricle of your heart, it flows through the aorta, a single large vessel with a diameter of about 2.5 cm. The speed of blood flow in the aorta is about 60 cm/s. Any change in pressure as blood flows in the aorta is due to the change in height: the vessel is large enough that viscous drag is not a major factor into successively smaller and smaller blood vessels until it reaches the capillaries. Blood flows in the capillaries at the much lower speed of approximately 0.7 mm/s. The diameter of capillaries and other small blood vessels is so small that viscous drag is a major factor..Because the flow speed in your capillaries is much less than in the aorta, the total cross-section area of the capillaries considered together must be much larger than that of the aorta. Given the flow speeds noted, the total area of the capillaries considered together is equivalent to the cross-section area of a single vessel of approximately what diameter?
a. 25 cm
b. 50 cm
c. 75 cm
d. 100 cm

Answer 1

Answer:

The correct option is c. 75 for this question

Explanation:

The correct option is c. 75 for this question:

Let's see how.

Continuity Equation is given as:

AcVc = AaVa

Where,

Aa = Area of Aorta

Ac = Area of the capillary

Va = Fluid speed in Aorta

Vc = Fluid speed in Capillary

So,

Assuming the fluid is the ideal one/

$\pi$/4 $Dc^{2}$ Vc= $\pi$/4 $Da^{2}$ Va

$Dc^{2}$ Vc= $Da^{2}$ Va

Dc = Da x $\sqrt{\frac{Va}{Vc} }$

Dc = 2.5 cm x $\sqrt{\frac{60 cm}{0.07 cm } }$

Dc = 73.192 cm

Dc = 75 approximately

Hence, the diameter of the capillary = 75 cm approximately