What is blood?

Your body carries aroundfourto six litres (7to 10.5 pints) of blood. Blood is made up of red blood cells, white blood cells and platelets in a liquid called plasma.

Plasma is about 90% water, but also contains proteins, nutrients, hormones and waste products. Blood is made up of about 60% plasma and 40% blood cells.

Each type of blood cell has a specific role to play:

  • red blood cells carry oxygen around the body and remove carbon dioxide and other waste products; they give blood its red colour
  • white blood cells are part of the immune system (the body's natural defence mechanism) and help fight infection
  • platelets help the blood clot (thicken) to stop bleeding
Content supplied by the NHS Website

Medically Reviewed by a doctor on 21 Dec 2018