BIO - blood

• red blood cells carry oxygen from the lungs to all the cells in the body
• RBC's shape is a biconcave disc - this gives a large surface area for absorbing oxygen
• RBCs do not have a nucleus - this allows more room to carry oxygen
• RBCs contain a red pigment called haemoglobin
• in the lungs haemoglobin binds to the oxygen to become oxyhaemoglobin. in body tissues, the reverse happens - oxyhaemoglobin splits up into haemoglobin and oxygen, to release oxygen to the cells
• white blood cells defend against infection
• some WBCs can change shape to engulf unwelcome microorganisms in a process called phagocytosis
• other WBCs produce antibodies to fight microorganisms, as well as antitoxins to neutralise any toxins produced by the microorganisms.
• white blood cells do have a nucleus
• platelets are small fragments of cells that help the blood to clot at a wound
• platelets have no nucleus
• platelets help the blood to clot at a wound - to stop all the blood pouring out and to stop microorganisms getting into the body
• a lack of platelets can cause excessive bleeding and bruising
• plasma is the liquid that carries everything in the blood
• plasma is a pale straw coloured liquid which carries just about everything
• plasma carries: red and white blood cells and platelets
• plasma carries: nutrients like glucose and amino acids
• plasma carries: carbon dioxide from the organs to the lungs
• plasma carries: urea from the liver to the kidneys
• plasma carries: hormones and proteins
• plasma carries: antibodies and antitoxins produced by the white blood cells