Blood is a fluid connective tissue. It helps in the transportation of oxygen, carbon dioxide, nutrients, hormones, etc. It also plays a vital role in the maintenance and regulation of pH, body temperature and thermo regulation process. The average adult should have about 5 to 6 liters of blood or blood volume. Blood is composed of plasma, protein and of different cells. William Harvey, an English physician was the first person to discover the blood and its circulation in the year 1628.
The main functions of the blood cells include:
- Movements of materials including processed and regulatory molecules in the body.
- Regulation of pH and osmosis.
- It maintenance the body temperature.
- It protects from loss of blood during injury by clotting the blood.
Below you could see 3 types of blood cells
Different Types of Blood Cells
- Erythrocytes ( Red blood cells )
- Leucocytes (White blood cells )
- Thrombocytes (Blood platelets)
Formation of blood cells: The formation of blood cells includes-hormones, erythrocytes, leucocytes, thrombocytes.
It contains hemoglobin to carry oxygen. They are biconcave disc shaped cells and their diameter ranges from 7 to 8 microns. They are produced at a rate of 2 million per second. They lack a nucleus and are biconcave in shape to increase surface and volume. Red blood cells pass through capillary beds in single file. The life span of each red blood cell is 120 days. Red blood cells are produced in the bone marrow.
Total count of erythrocytes (RBC) is 4.6 – 6.0 millions. This blood count varies from newborn baby, children, males and females.
Why the Colour of Blood is Red?
Blood is red in colour, it is because of hemoglobin. It is a pigment that contains iron and it helps in transportation of oxygen, which gives blood its red color. Hemoglobin in red blood cells is made of four polypeptides: Two alphas and two betas, which contain a heme unit. Each heme carries oxygen. There are about 280 millions of hemoglobin molecules present in each RBC. Other molecules, such as carbon dioxide and nitrogen oxide are also carried by this hemoglobin.
They are the part of the immune system, which functions by destroying infectious agents called pathogens. Leukocytes are nucleotide blood cells, which includes both granulated cells and a-granulated cell. A leukocyte plays a vital role in maintaining a healthy immune system. It is also called as white blood cells (WBC). This is due to their white in colour. These blood cells have an ability to move in and out of blood vessels and can respond to chemicals released by damaged tissues. The size of WBC ranges from 10 to 12 microns and the lifespan of white blood cells ranges from 13 to 20 days. The white blood cells are produced in the lymph nodes.
Total count of WBC is 4,500 - 10,000.This blood count ranges from males to females.
Thrombocytes are small fragments of megakaryocytes with the presence of purple granules containing serotonin. These cells are found in the bone marrow and play a vital role in blood clotting. Thrombocytes are normally 2 to 3 microns in diameter and their production is controlled by thrombopoietin. The lifespan of thrombocytes is for 8 to 10days.
Total count of platelets is 300,000/mm3.