What exactly is blood!

Find out what blood is made of, plus learn other interesting facts about that stuff in your veins.

What are the major components of human blood?

The three main types of cells within blood are the red blood cells, white blood cells and platelets. White blood cells are the largest of the three types of cells and are responsible for fighting infections or germs. Red blood cells carry oxygen to the cells of your body and return to the lungs to excrete carbon dioxide. Platelets are the smallest of the cells, and their job is to form clots [scabs] in the blood to help stop bleeding. The other major component of blood is the plasma. Plasma is a sticky fluid that is 95% water. The other 5% is made up of nutrients, proteins and hormones.

What do these cells look like?

	Red blood cells- these cells make up approximately 40% of the total blood volume.
	White blood cells have a rather short life cycle, living from a few days to a few weeks. A drop of blood can contain from 7000 to 25000 white blood cells. If an invading infection fights back and persists, that number will significantly increase.
	Basophil - first of five distinct white blood cell types. These cells act on smooth muscle and blood cell walls. Eosiniphil - second type of white blood cell. Can act against infestations of parasitic larvae. Lymphocyte - third type of white blood cell. Lymphocytes recognize surface markers on cells and target them for destruction if they are foreign to the body. Monocyte - fourth type of white blood cell. Formed in the bone marrow, monocytes migrate into connective tissue and become macrophages. Neutrophil - fifth type of white blood cell. First line of defense. 100 billion fresh, mature neutrophils are released into the body everyday from the bone marrow.
	Platelets - these cells make up 5%-7% of the total blood volume. Platelets form a mesh type net to stop bleeding.

What are the blood types and their percentages?

Each person's blood contains a specific and inherited set of antigens, or proteins, on the surface of their red blood cells. Paired with red cell antigens, your plasma contains a specific set of antibodies that will attack antigens attached to the surface of red blood cells of another blood type. Consequently, successful blood transfusion requires the matching of blood to avoid giving blood cells to a person whose plasma contains antibodies to the antigens on the blood cells of the transfused blood.

The following is a breakdown by ABO and rh type:

	O positive	37.4% of population	1 person in 3
	A positive	35.7% of population	1 person in 3
	B positive	8.5% of population	1 person in 12
	O negative	6.6% of population	1 person in 15
	A negative	6.3% of population	1 person in 16
	AB positive	3.4% of population	1 person in 29
	B negative	1.5% of population	1 person in 67
	AB negative	0.6% of population	1 person in 167

What blood types can I receive?

	Your Blood Type	Can Receive
		O-	O+	B-	B+	A-	A+	AB-	AB+
	AB+	X	X	X	X	X	X	X	X
	AB-	X		X		X		X
	A+	X	X			X	X
	A-	X				X
	B+	X	X	X	X
	B-	X		X
	O+	X	X
	O-	X

Why is O type blood so important?

Of all blood types, type O is the most common. At the same time, it is a special blood type because there is always an uncommon need for it. Currently, hospital patients need type O blood in at least 51% of transfusions.

Type O patients can only receive type O blood. In addition, there are special cases that add to the strain on the type O blood supply:

Universal donors - O negative blood can be safely transfused to patients of all blood types. Donors who are O negative are considered universal donors. O positive blood can be safely received by patients with any of the positive blood types.

Premature babies - premature babies have an increasing chance of survival thanks to improvements in medical care and technology. A premature baby's life can depend on blood transfusions, but the usual crossmatching and blood typing procedures may not be possible. Many hospitals transfuse only type O blood to these babies.

Trauma patients - in some emergencies, the patient needs a transfusion immediately. There is no time to crossmatch blood. Often, the patient receives type O blood until the emergency is over and the patient is stable.

What are the components of blood used to treat?

When you come to donate a unit of blood, that unit is not kept in its whole blood form. The unit is centrifuged at high speeds to separate the constituent components from each other. Since red blood cells are the heaviest, they sink to the bottom of the bag. The platelet rich plasma and cryoprecipitate factors settle near the middle of the bag. Each of these components are separated into different bags to accomplish these areas of treatment:

Red blood cells	Used to increase red cell mass after surgery, to treat patients with anemia
Fresh frozen plasma	To treat clotting disorders, expand blood volume, to treat shock due to plasma loss in burns
Platelets	To treat bleeding due to platelet shortage or to treat platelet function abnormalities
Cryoprecipitate	To treat Hemophilia A, Von Willebrand's disease, and other clotting factor deficiencies
White blood cells	To treat patients who cannot produce enough white cells, due to disease or cancer treatment
Immune globulin	Given to help fight infectious diseases such as hepatitis
Albumin	To treat people in shock, and also used in plasma exchanges for seriously ill patients

Please remember, your one unit of blood can save as many as four lives!

How much blood can a patient use?
It is difficult to put an exact figure on each type of procedure or illness, but listed below are general estimates for the top blood using events:

Hip replacement surgery - 3 to 4 units
Leukemia treatment - 6 to 8 units
Stab wound/gunshot - 6 to 12 units
Heart surgery - 6 to 12 units
Gastro-intestinal bleeding - 5 to 50 units
Aortic/abdominal aneurysm - 5 to 50 units
Traumatic organ damage - 10 to 100 units
Liver transplant - 30 to 150 units.