Blood transports materials and distributes heat around the body. It also helps to protect against disease. Blood contains plasma, which is a liquid that cells and cell fragments are suspended in:
Plasma is a straw-coloured liquid that makes up just over half the volume of blood.
Types of blood cell and cell fragments:
This table explains the functions of various blood components.
|Plasma||Transporting carbon dioxide, digested food molecules, urea and hormones; distributing heat|
|Red blood cells||Transporting oxygen|
|White blood cells||Ingesting pathogens and producing antibodies|
|Platelets||Involved in blood clotting|
Red blood cells transport the oxygen required for aerobic respiration in body cells.
Haemoglobin can combine reversibly with oxygen. This is important - it means that it can combine with oxygen as blood passes through the lungs, and release the oxygen when it reaches the cells.