The blood is suspended in a special cell in liquid form that is called ‘plasma.’ Blood has 55% plasma and 45% cells that are called ‘formed elements.’

The blood has so many important functions in the body. With the help of hemoglobin that is contained within the erythocytes, blood carries the oxygen to the tissues and also collects carbon dioxide. It conveys the substances of nutrition, specifically amino acids, mineral salts and sugar, and collects the excreted components that are eliminated through a renal filter.

Blood carries enzymes, vitamins and hormones. It also serves as the defense to organisms or parasites, particularly the leukocytes, bacteria and fungi.

The Plasma
Plasma is an alkaline fluid that is generally colored yellow. It has 90% water and 10% dry components. Nine parts of plasma are made from organic substances while the remaining part is made out of mineral. This organic substance is composed of glucose, lipids (such as cholesterol, lecithin, fat, triglycerides, phospholids) proteins (such as albumins, globulins and fibrinogen), glycoproteins, hormones (such as thrombopoietin, erythropoietin, gonadothropins), vitamins and amino acids. The mineral substances are later on dissolved into an ionic form that is eventually dissociated into negative and positive ions.

The Hematic Cells
There are present special cells in the blood that are categorized into two. The erythrocytes and the leukocytes. Then there are the platelets which aren’t real cells.

1. Erythrocytes
These are the red cells. They are quite numerous. Normally they are 4 to 6 million. They are also called the red blood cells. They do not have nucleus and are shaped like a biconcave lens.

Red blood cells are rich in hemoglobin. This is a protein that is bound to oxygen. These cells are responsible in providing the oxygen to the tissues and in recovering the carbon dioxide that are eventually produced as waste products.

Because of the lack of nucleus, the hemoglobin and the biconcave shape of the cells increase the surface as well as the cytoplasmic volume ratio of the blood. These in turn make the plasma more efficient to the oxygen diffusion created by the red blood cells.

A low red blood cell count equates to aneamia. If this is the case. The erythrocytes are sickle-shaped. With the use of the electron microscope, health professionals and biologists can see that the red blood cells have different shapes, depending on its kind – be it a discocyte, crenate, echnicyte, codocyte or poikolocyte.

2. Platelets
The primary function of the platelet is to prevent the loss of blood when the individual obtains wounds. In order to do this, they release the factors promoting blood coagulation. An example is seratonin. This reduced the lesioned vessels in diameter and also slows down the flux in the hematics. They may not be real cells but they still give a purple color.

3. Leukocytes
Leukocytes or the white blood cells are responsible in defending the body from any organism. There are less white blood cells than red blood cells.

Leukocytes are divided into two categories: the lymphoid cells and the granulocytes. The lymphoid cells distinguish themselves as monocytes and lymphocytes whereas the granulocytes distinguish themselves as eosinophil, basophil and neutrophil.

Take note that a leujkocyte is composed of the following:

neutrophil – 50 to 70%
eosinophil – 2 to 4 %
basophil - .5 to 1 %
lymphocyte – 20 to 40 %
monocyte – 3 to 5 %

Lymphocytes are cells that are present in the blood and populate the organs as well as the lymphoid tissues by circulating in the lymphatic vessel. This includes the bone marrow, spleen, thymus, nodules, lymphoid and palatine tonsils.

Most of the lymphocytes that circulate the blood are resting. They may look like tiny cells that are resting in a round nucleus but over time, they are reduced. They are activated in various amounts depending on the stimulation of the antigenes.

Monocytes are the larger blood cells that gain maturity within the bone marrow. They enter the blood and stay there for a day to a day and a half. Then they move through the connecting tissue where they eventually become macrophages and link themselves together with the tissue.

Eosinophil is responsible in attacking parasites and serve as antigen-antibodies to the infected phagocyes.

Basophils secrete the vasodilatory and anti-coagulant substances like serotonin and histamines. Their main responsibility is to serve as mediator in the hypersensitivity reaction.

Neutrophils are quite active in the presence of bacteria in the blood. It is responsible in renewing the lysosomes that have been digested by the microbes and left for dead.

If these theories leave you still thirsty for more blood cells information, using blood microscopes can help you view more about them.