Blood Flow in Arteries

As shown on the previous page, arteries are the blood vessels taking blood away from the heart. The heart is a very powerful muscle - so the blood is ejected out at a high velocity and with high pressure.

As the heart beat approximately once every second, the pressure and flow increases once per second.

To withstand this regular increase of flow and pressure, the arterial walls have to be strong (to withstand the pressure), elastic and muscular (to dilate when the pressure pushes outwards, and to bounce back to normal shape when the pressure pulse passes.

The walls of the arteries have 3 main layers and a special lining that is contact with the blood.

The most important layer for us to note is the Media which is a thick muscle layer.
It is the Media give the arteries the "bounce" that let them return to their normal shape after the heart has pumped blood through them at high pressure.

You can feel this "bounce" in some areas of the body such as at the wrist - this is called the "Pulse" (see the animations below to understand how the pulse comes from the heart pumping blood through the arteries).

The Endothelium is the innermost part of the layer called the Intima. The Endothelial cells are as single layer of cells that are in contact with the blood.

They have special substances on their surface that stop the blood from clotting on them in normal circumstances.