Page 12, CV Review, Essentials, Develop. Physiol., Dr. D. Penney




Misconception 14. Flow velocity in veins is always low (sluggish).

The mean velocity of blood flow can be calculated if you know the volume flow per sec. and the cross-sectional area. For example, if the volume flow for the vena cava is 100 ml/sec (6 l/min) and the area is 4 square cm. - then the velocity is about 25 cm/sec. The cross-section of the blood vessel is assumed to be a circle, thus the area is equal to pi*r2. This velocity is only about 25% less than the mean value observed in the aorta.

Thus, velocity in this largest vein in the body (Vena Cava) is very substantial - but is anything but sluggish.


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