Describe the components of formed elements in the blood and mention the major function of each of them

The components of formed elements are:

(i) Erythrocytes- Theyare red in colour due to the presence of iron

containing complex protein called haemoglobin, hence they are also termed

as red blood cells (RBC).They are the most abundant of all the cells in blood and formed in the red bone marrow in the adults. RBCs are biconcave in shape and are

devoid of nucleus in most of the mammals. A healthy individual has 12-16 gms of

haemoglobin in every 100 ml of blood.

Functions of Erythrocytes:

- The haemoglobin present in them transports oxygen and carbon dioxide.

(ii) Leucocytes- They are colourless due to the lack of haemoglobin and are also

known as white blood cells (WBC). They are nucleated and in comparison to RBC they are relatively lesser in number. The two type of WBCs are granulocytes which

contain neutrophils, eosinophils and basophils and agranulocytes which contain

lymphocytes and monocytes.

Functions of Leucocytes:

- Neutrophils and monocytes are phagocytic cells and destroy any foreign organisms

and provide protection against infections.

- Basophils secrete histamine, serotonin, heparin, etc., and are involved in inflammatory reactions.

- Eosinophils are associated with allergic reactions.

(iii) Thrombocytes- Thrombocytes are cell fragments produced from megakaryocytes and are also termed as platelets.

Functions of Thrombocytes:

- Theyare involved in the coagulation or clotting of blood during an injury and thus prevents the excessive loss of blood from the body.