Body & Health

Body & Health home   Digestion   Lymph System   Blood   Cholesterol   Diabetes   Alzheimer's   Cancer   Amalgam   Flu/Colds   Fever   Misc   Disclaimer  

Blood is the fluid that circulates in a person's heart, arteries, veins and capillaries, carrying nourishment and oxygen to all parts of the body. Blood contains blood cells, nutrients, hormones, clotting agents, and waste products. Waste products are removed from the blood by the kidneys.

There are three kinds of cells in the blood: red blood cells, white blood cells, and platelets. Red blood cells carry oxygen from the lungs to the body's cells and bring carbon dioxide back to the lungs which is then exhaled. White Blood Cells protect the body against infection and disease, fight bacteria and help the body develop immunity to disease. Platelets help in clotting.

About 8 percent of a person's weight is blood. The amount of blood varies according to height and weight, but an average man has about 12 pints of blood, an average woman has about 9 pints and a newborn baby has approximately one cup of blood in his/her body.

Blood cells are produced in the bone marrow. Bone marrow is a jellylike substance inside the bones composed of, among other things, fat, blood, and special cells that turn into the various kinds of blood cells. Some cells are made in the spleen and lymph glands. In children, the marrow of most of the bones produces blood. In adults, only the marrow of certain bones -- the spine, ribs, pelvis, and some others -- continues to make blood. Bone marrow that actively produces blood cells is called red marrow, and bone marrow that no longer produces blood cells is called yellow marrow.

Different kinds of blood cells have different life spans. Red blood cells last about 120 days in the bloodstream, platelets about 10 days and the various kinds of white blood cells can last anywhere from days to years.

There are eight different blood types. The general United States population is made up of the following types:

O positive 38%
O negative 7%
A positive 34%
A negative 6%
B positive 9%
B negative 2%
AB positive 3%
AB negative 1%

Plasma (over 50% of your blood) is a clear, straw-colored liquid that carries the blood cells and various hormones, nutrients, and so on through the body. It makes up a little more than half of the total blood volume. Plasma is about 90 percent water. Much of the other ten percent comprises various kinds of protein molecules, including enzymes, clotting agents, immunoglobulins (part of the immune system), and proteins that carry hormones, vitamins, cholesterol, and other things the body needs. Plasma also contains sugar (glucose) and electrolytes like sodium, potassium, and calcium, as well as other things like hormones, vitamins, and cholesterol.

Red Blood Cells (erythrocytes) (about 45% of your blood) are what cause your blood to be red. They carry oxygen to cells and carry carbon dioxide to the lungs, to be breathed out. Red blood cells contain a special molecule called hemoglobin, which carries oxygen. In the lungs, where there is a lot of oxygen, the hemoglobin molecules loosely bind with oxygen. In the capillaries, where there is little oxygen, the hemoglobin readily sheds the oxygen it is carrying and allows it to be absorbed by the body's cells. The iron in hemoglobin is what makes blood red.

Platelets (thrombocytes) (about 5% of your blood) help blood to clot, in several different ways. When bleeding occurs, platelets clump together to help form a clot. When they are exposed to air (as they would be by a wound), platelets start breaking down and release a substance into the bloodstream. This substance starts a chain of chemical events that eventually causes a protein in the blood, fibrinogen, to turn into a different substance, fibrin, which forms long threads. These threads tangle up red blood cells to help form a clot, or scab, over the wound. Platelets are the smallest kind of blood cell.

White blood cells (leukocytes) (less than 1% of your blood) are the body's mobile warriors in the battle against infection and invasion. They break down dead cells. There are three types of white blood cells: granulocytes, lymphocytes, and monocytes. There are, in turn, three kinds of granulocyte: neutrophils, eosinophils, and basophils. Granulocytes contain digestive enzymes. Neutrophils kill invading bacteria by ingesting and then digesting them. Eosinophils kill parasites, and are involved in allergic reactions. Basophils also function in allergic reactions.

Earthworms, leeches, and insects have green blood. Starfish and many other invertebrates have clear or yellowish blood. Lobsters and crabs have blue blood because it contains copper instead of iron.

There is a theory of how to eat based on your blood type. Here it is in a nutshell:

Type A blood types should basically stick to fruits and vegetables (high carbs / low fat), and should not consume dairy products, animal fats and meats.

Type B blood types should consume a balanced diet (fruits and vegetables, grains, fish, dairy, meat, but avoid chicken).

Type AB blood types should consume a mostly vegetarian diet, and only on rare occasions some fish, meat (no chicken), and dairy.

Type O blood types should basically stick to a high protein diet (including red meat), low carbs, fruits and vegetables. They should limit the intake of wheat germ, whole wheat products, corn, and avoid dairy products and most nuts.

Jump to: Top of Page