The aorta carries blood away from the heart at a speed of about40 cm/s and has a radius of approximately 1.1 cm.
The aortabranches eventually into a large number of tiny capillaries thatdistribute the blood to the various body organs.
In a capillary,the blood speed is approximately 0.007 cm/s, and the radius isabout 6.0 10-4 cm.

Treat the blood as an incompressiblefluid, and use these data to determine the approximate number ofcapillaries in the human body.

Respuesta :

Answer:

The no. of capillaries are [tex]1.92\times 10^{10}[/tex]

Solution:

As per the question:

Speed of the blood carried by the aorta, [tex]v_{a} = 40\ cm/s[/tex]

Radius of the aorta, [tex]R_{a} = 1.1 cm[/tex]

Speed of the blood in the capillaries, [tex]v_{c} = 0.007\ cm/s[/tex]

Radius of the capillaries, [tex]R_{c} = 6.0\times 10^{- 4} cm[/tex]

Now,

To determine the no. of capillaries:

Cross sectional Area of the Aorta, [tex]A_{a} = \pi R_{a}^{2} = \pi \times (1.1)^{2} = 1.21\pi \ m^{2}[/tex]

Cross sectional Area of the Capillary, [tex]A_{c} = \pi R_{c}^{2} = \pi \times (6.0\times 10^{- 4})^{2} = (3.6\times 10^{- 7})\pi \ m^{2}[/tex]

Let the no. of capillaries be 'n'

Also, the volume rate of flow in the aorta equals the sum total flow in the 'n' capillaries:

[tex]A_{a}v_{a} = nA_{c}v_{c}[/tex]

[tex]1.21\pi\times 40 = n\times 3.6\times 10^{- 7}\pi\times 0.007[\tex]

[tex]n = 1.92\times 10^{10}[/tex]