Blood notes
Constituents of blood...
Red blood cells contain haemoglobin, an iron-containing protein, which facilitates transportation of oxygen by reversibly binding to this respiratory gas, and greatly increasing it's solubility in blood. In contrast, carbon dioxide is almost entirely transported extracellularly, dissolved in plasma as bicarbonate ion.

Red cells live for 120 days, and have a density of 5 million/mm³. White cell density is 5,000 - 10,000/mm³.

Adult (70 kg)...
Platelets aggregate at site of injury, causing a plug, and preventing capillary bleeding, and local vasoconstriction. To arrest haemorrhage, Fresh Frozen Plasma (contains clotting factors) and platelets needed. Normally, body has balance of coagulation and clot breakdown (fibrinolysis) factors.
Blood groups...

AB people do not possess any factor likely to cause blood group incompatibility due to agglutination.

Group O people have anti-A and anti-B agglutins but, by the time these agglutins are diluted into the recipient, the amounts in the plasma will be insufficient to cause agglutination. Group O people are universal donors, but must be Rhesus Negative.

Only when transfusion of blood is completed, is it necessary to cross match and group blood, because agglutinogens A and B are only present on the surface of red cells. Plasma and other products can be given without cross matching procedures.
Blood test bottle top colour codes
Colour Test
Pink Blood group, Transfusion cross match
Lavender FBC, Viscocity, Sickle cell, HIV
Grey Glucose, Lactate (blood , CSF)
Gold Biochemistry, Thyroid
Light blue Clotting (coag), Thrombophilia, Lupus
Red Immunology
White Immunology
Yellow Transplant immunology