Flow in Normal Vessels

Blood is pumped around the body by the heart. Blood is pumped from the heart at high pressure and at high flow in blood vessels called Arteries. Blood goes on through the arteries to the tissues and then back to the heart through the Veins.

When people say they have "poor circulation" they are usually talking about diseases or conditions affecting the Arteries.  Claudication is caused by problems with the arteries. Conditions affecting the veins include varicose veins, leg ulcers and deep venous thrombosis - if you want to know more about these relevant sites are listed on www.TheWhiteleyClinic.co.uk.

To understand claudication, including its investigation and treatment, we have to understand flow in the arteries. I have arranged the following pages into an easy to follow series of explanations of how blood flows in normal and diseased arteries.

By using animations, you will get a clear idea of how blood flow and the pressure of the blood is affected by arterial disease.

Flow in Normal Artery:

The animation on the left shows what happens in the normal artery in normal circumstances.

As you can see, blood being pumped from the heart flows easily along the artery. If you look closely, you will see on each heart beat that the flow near the wall flows slower than the blood in the middle of the artery.

This is due to friction of the blood on the artery wall, slowing the blood in contact with it. Blood further away from the wall has less friction from the wall and so can flow easier. This is called Laminar Flow.

Pressure Change in Normal Artery:

The animation on the right shows the same situation artery as shown above - ie: normal or laminar flow. The only difference in this animation is that I have added two pressure measures - labelled P1 and P2. Think of these as sort of thermometers - but measuring the pressure of the blood in the artery.

Not surprisingly, the pressure in the blood at P1 is almost identical to that at P2 as the two points are close together and the flow is laminar between the two points.