Blood is the main circulatory medium in the human body. The blood consists of two principal components: the fluid plasma and blood cells or corpuscles which are found suspended. Nearly 45% volume of blood consists of corpuscles or blood cells. These are of different types: the erythrocytes or red cells containing hemoglobin; the leucocytes or white cells having no hemoglobin, and the thrombocytes in mammals only. These are essential for proper functioning of the body.
Erythrocytes vs Leucocytes
Erythrocytes (Red Blood Corpuscles or RBCs)
1. They are red coloured blood corpules.
2. Number: 4.5-5.5 million/mm3
3. shape and size: Circular and bioconcave, 7-8 mm
4. They are nonmotile
5. Erythrocytes seldom leave blood vessels.
6. Most of the cell organelles are absent. Nucleus is absent.
7. They contain hemoglobin.
8. They may form stacks called rouleaux.
9.Erythrocyte are of one type.
10. Life span:120 days
11. They are specialized to transport oxygen and small amount of carbon dioxide.
12. They have no role in defence and immunity of the body.
13. Number increases during exercise and at high altitudes.
Leucocytes (White Blood Corpuscles or WBCs)
1. They are colorless corpules.
2. Number: 7000-10000/mm3
3. shape and size: rounded and amoeboid shape. The size is 10-18 mm with the exception of small lymphocytes.
4. They are generally motile
5. They can come out of blood capillaries.
6. Most of the cell organelles are present. Nucleus is present.
7. They do not contain hemoglobin.
8. Rouleaux formation is absent.
9.Erythrocyte are of five types.
10. Life span: 12- 13 days.
11. They do not have any respiratory function.
12. They have important role in defence and immunity of the body.
13. Number increase during infection