TRANSPORTATION

All body cells receive oxygen through erythrocytes, or red blood cells, which contain haemoglobin. Nutrients and other essential elements are dissolved by blood plasma and subsequently transported to tissues via arteries and capil­laries. Blood travels through veins to carry waste prod­ucts from cellular metabolism to the kidneys and lungs, where they are eliminated from the body. Blood delivers hormones from endocrine glands to target organs and car­ries white blood cells to various sites of activity where they aid in the body’s defence against infection. The process by which blood transports platelets to damaged blood vessel walls in order to form a plug that will stop the bleeding is known as haemostasis. Platelets also initiate the cascade that clots blood.

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