Blood is a highly specialised circulating tissue that consists of red blood cells, white blood cells and platelets suspended in a fluid medium known as plasma. The red blood cells are packed with haemoglobin, which is made up of an iron compound (haem) and a protein (globin). Oxygen binds itself to the iron compound, which enables it to be carried around the body to supply all the body's tissues and organs. White blood cells (also known as leukocytes), help the body to fight disease, whilst platelets are cell fragments that play an important part in the clotting of the blood. Medical terms related to blood often begin with haemo- and haemato- from the Greek word 'haima' for 'blood'.
Blood is used to carry out many functions, including the supply of oxygen and nutrients to tissues; the removal of waste such as carbon dioxide, urea and lactic acid; the regulation of core body temperature and pH; immunological functions including the detection of foreign bodies; coagulation; the transport of hormones and the signalling of tissue damage.
The lymphatic system is a major component of the immune system that produces and transports lymph fluid from tissues to the circulatory system. It has three major functions: the production of immune cells, the removal of excess fluids from body tissues, and the absorption of fatty acids and subsequent transport of fat to the circulatory system.
In this section, you can learn about the disorders that may affect blood and the lymphatic system, including details of their causes, symptoms, means of diagnosis and treatment.
