New News Biology #17

Blood Vessels

Arteries = Containing Blood Flowing Out of Heart

Because the blood in the arteries are constantly at a high pressure, so the arteries are adapted to have thick, strong elastic walls

It also has a rather narrow lamen (the hollow part of the blood vessel), compared to the thickness of the elastic/muscular walls

Capillaries = Branches Out From the Arteries

The capillaries are really small, and are used to exchange substances (nutrients & oxygen) with the cells of our body, in addition to taking away the waste (carbon dioxide) from those cells.

Considering it has to exchange substances at a high rate, the walls of the capillaries are only a single cell think and are permeable.

Veins = Blood Flowing Back to the Heart

The veins contain one-way valves that prevent blood from flowing backwards, and only have a single layer of cells because it is not pumped at a high pressure (in comparison to the arteries).

They also house the biggest lumens yet.

Calculating Rate of Blood Flow = ml of blood ÷ min. taken