Expert: Walter Hintz - 6/28/2006

Question
I just read that the human circulatory system has its blood distributed: 75% veins, 20% arteries and 5% capillaries.  Two questions: Is this common among all mammals?  Is there a physiological reason for it?  Thanks.

Answer
Hi Bob; I am not acquainted with thsi study so all I can say is that since all mammals have similiar circulatory systems this distribution would be common with exceptions perhaps in hibernating mammals.
 As to your second question I can only suggest that there is a physiological reason for it.  It is what works best.  A different distribution of blood. would be detrimental to the animal