Question

Human blood circulation system has about 1×10^9 capillary vessels. Each vessel has a diameter 8μm (1μm=1.0×10^(-6) m). Assuming the cardiac output is 4.8 L/min, determine the speed of blood flow through the capillary vessel.

Answer 1

1 L = 10^-3 m³

1 min = 60 sec

Flow rate of blood = Q = 4.8 L/min

Converting to m³/s,

$Q = 4.8 \times (\frac{10^{-3}}{60})$

Q = 8 x 10^-5 m³/s

Diameter of the capillary = D = 8 $\mu$m = 8 x 10^-6 m

Cross-sectional area of one capillary = A

A = $\pi$D²/4

A = $\pi$(8x10^-6)²/4

A = 5.0265 x 10^-11 m²

Number of capillary vessels = n = 1 x 10⁹

Speed of the blood flow through the capillary vessel = V

Q = nAV

8x10^-5 = (1x10⁹)(5.0265x10^-11)V

V = 1.59 x 10^-3 m/s

Speed of blood flow through the capillary vessel = 1.59 x 10^-3 m/s