2. Blood is a constantly circulating fluid providing the body with
nutrition, oxygen, and waste removal. Blood is mostly liquid, with
numerous cells and proteins suspended in it, making blood "thicker"
than pure water. The average person has about 5 liters (more than a
gallon) of blood.
3. A liquid called plasma makes up about half of the
content of blood. Plasma contains proteins that help
blood to clot, transport substances through the blood,
and perform other functions. Blood plasma also
contains glucose and other dissolved nutrients.
4. A blood cell, also called a hematocyte, is a cell produced by hematopoiesis and normally found
in blood. In mammals, these fall into three general categories: Erythrocytes (RBC’S) , Leukocytes (
WBC’S) ,Thrombocytes ( Platelets).
Together, these three kinds of blood cells add up to a total 45% of the blood tissue by volume, with
the remaining 55% of the volume composed of plasma, the liquid component of blood. This volume
percentage (e.g., 45%) of cells to total volume is called hematocrit, determined by centrifuge or
flow cytometry .Hemoglobin (the main component of red blood cells) is an iron-containing protein
that facilitates transportation of oxygen from the lungs to tissues and carbon dioxide from tissues to
the lungs.
5. Erythrocytes(Red Blood Corpuscles)
A cell that contains hemoglobin and can carry oxygen to the body. Also called
a red blood cell (RBC). The reddish color is due to the hemoglobin.
Erythrocytes are biconcave in shape, which increases the cell's surface area
and facilitates the diffusion of oxygen and carbon dioxide. This shape is
maintained by a cytoskeleton composed of several proteins. Erythrocytes are
very flexible and change shape when flowing through capillaries. Immature
erythrocytes, called reticulocytes, normally account for 1-2 percent of red cells
in the blood.
6. Leukocytes ( White Blood Corpuscles)
They are a part of the immune system and help our bodies
fight infection. They circulate in the blood so that they can be
transported to an area where an infection has developed. In
a normal adult body there are 4,000 to 10,000 (average
7,000) WBCs per micro liter of blood. When the number of
WBCs in your blood increases, this is a sign of an infection
somewhere in your body.
7. Thrombocytes (Blood Platelets)
The blood platelets are the smallest cells of the blood, averaging about
two to four micrometers in diameter. Although much more numerous
(150,000 to 400,000 per cubic millimeter) than the white cells, they
occupy a much smaller fraction of the volume of the blood because of
their relatively minute size. Like the red cells, they lack a nucleus and
are incapable of cell division (mitosis), but they have a more complex
metabolism and internal structure than have the red cells. When seen in
fresh blood they appear spheroid, but they have a tendency to extrude
hair like filaments from their membranes. They adhere to each other but
not to red cells and white cells. Tiny granules within platelets contain
substances important for the clot-promoting activity of platelets.
