Biggest Blood Pressure in Body

[blazinfury]

I am trying to understand where blood pressure would be the largest. In a book that I was reading, it said that blood would be bigger near the heart (such as in the arms) than in the toes. I could see that being true since the left ventricle has the highest blood pressure in that it must pump blood with enough force for it to constantly circulate throughout the body. However, based on the physics definition of pressure where pressure increases with depth, wouldn't pressure be largest in our toes?

 

Also I have a side quest about pressure and height. If one is comparing the blood pressure of individuals with varying height, the taller person would have a higher blood pressure than the smallest person because the heart must contract with more force to circulate blood, esp to the head. So that is why a giraffe would have a very high blood pressure, compared to see a human (who is shorter).

[sysD]

3545

Edited March 30, 2013 by sysD

[Nehushtan]

However, based on the physics definition of pressure where pressure increases with depth, wouldn't pressure be largest in our toes?

Wrong definition to use. The principle that pressure increases with depth applies to the pressure exerted by a fluid on an object immersed in the fluid. Blood pressure on the other hand is the pressure exerted by blood on the walls of blood vessels due to the circulation of blood.

 

Try the other physics definition of pressure: pressure = force/area. Thus blood pressure depends not only on the pumping action of the heart (force) but also on the size of the blood vessels: blood pressure is greater in blood vessels with smaller cross-sectional areas. This is why people with high blood pressure are given vasodilator drugs: these relax the walls of blood vessels, increasing their cross-sectional areas and lowering blood pressure.

[blazinfury]

Thank you very much for that clarification.