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The red coloured
liquid that flows around your body is called blood. It performs two
important functions. First, it acts as a transport medium carrying
various substances from one part of the body to another. Secondly,
it protects the body against organisms.
The normal path of
blood around the body is a double circulation - from the heart to
lungs, back to the heart and then to all parts of the body. This
cycle repeats itself, with blood passing through the heart two times
before each cycle is complete, thus "double circulation".
The blood
transports the following
- Digested food substances from the
intestines to all parts of the body.
- Excretory products from the
tissues to the respective excretory organs for removal.
Nitrogenous waste materials (urea, uric acid, creatinine) are
removed mainly by the kidneys. Carbon dioxide from the cells
enters the blood and is carried as bicarbonate in the blood
plasma. As the blood passes through the lungs the bicarbonate
ions dissociate, setting free carbon dioxide into the lung
cavities, and the carbon dioxide is then expelled during
expiration.
- Hormones from the glands which produce them to parts of the
body which require them.
- Heat produced in body tissues, especially the muscles and
liver, and distributes it throughout the body, thereby
maintaining a uniform body temperature.
- Oxygen from the lungs to all parts of the body.
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©Copyright TQ Team 25896, 1999. The Circulatory System- Online Learning.
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