The Circulation - the Circulatory System 2
 

Although the circulatory system is a closed system where blood it keeps on being pumped around the same blood vessels, it is useful to think of it as having a start and and end.

By thinking of the circulation having a beginning and end, we can understand how the whole system works, step by step.

The first step is to think of the heart pumping blood that is full of oxygen "oxygenated blood" and food, to the whole of the body. Oxygenated blood is bright red.

The heart pumps the oxgenated blood at high pressure, through thick walled blood vessels called arteries.

The first and most major artery is the aorta and then this branches off into many other big arteries, which then in turn branch into many smaller arteries.

After branching several times, the arteries are very small and these feed into even smaller blood vessels called arterioles.

The arterioles then take the blood to the tissues through a network of very fine blood vessels called capillaries.

The walls of the capillaries are so thin, fluid, oxygen and nutrients (eg: sugars, amino-acids from proteins, fatty acids and vitamins) pass out of the blood, through the capillary wall and into the tissues. Here the fluid is called the extra-cellular fluid (ECF) as it bathes the cells of the tissue, making sure the oxygen and nutrients get to all of the cells of the tissue.

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For more information about vascular and circulatory diseases and disorders, visit our Vascular specialist websites page

(information provided by Mark Whiteley - www.TheWhiteleyClinic.co.uk)