Blood is made up of cells in a watery base, called plasma. There are three major types of cells in blood – red blood cells (RBCs), while blood cells (WBCs) and platelets.
- Red Blood Cells (RBCs) or erythrocytes
- White Blood cells (WBCs) or leukocytes
- Platelets or thrombocytes
These cells float around and are carried through the body in a fluid known as plasma.
Blood is a fluid that flows through the body. It is thicker than water and is salty to taste. There are about 10.6 pints of blood that circulates through the body of a normal adult. Read the following blood constituents:
Red blood cells:
Red blood cells are also known as erythrocytes, carry oxygen to various parts of the body.
- They are the most in number, constituting about 40-45% of blood. Their structure is like that of dough nuts.
- They contain haemoglobin, which contains iron and protein and helps carry oxygen throughout the body.
- The iron present in RBCs makes blood appears red in color.
White blood cells:
- They are also called leukocytes, They protect body systems from infections, diseases by fighting viruses, bacteria and other such harmful invasions.
- They are of three types, namely, monocytes, lymphocytes and granulocytes.
- Granulocytes are of three types – neutrophils, basophils and eosinophils.
- Neutrophils destroy invasive bacteria by ingesting and then digesting them.
- Eosinophils destroy parasites and play a part in allergic reactions.
- Basophils also play a part in allergic reactions, but their role is not yet clear.
- Lymphocytes are extremely important to the immune system. They are of two types – T cells and B cells.
- T cells tell the immune system about invasions and external activity.
- B cells produce antibodies that destroy foreign harmful bodies.
- Monocytes are the largest of WBCs which become even bigger on entering tissues and are called macrophages.
- They ingest foreign bodies and help rid the body of damaged and dead cells.
- They are also called thrombocytes, help in clotting of blood and also help prevent internal bleeding.
- They are essential in maintaining wear and tear of the body.
- They are important in stopping bleeding in case of an external wound or abrasion.
- They are shaped like plates when inactive and that is the reason why they are called platelets. They are the smallest of the blood cells.
- This is the fluid in which these cells are present and which carries these cells all over the body.
- It is made up of 90% water.
- The rest 10% consists of the cells mentioned above along with proteins, vitamins, minerals, glucose, hormones and many other essential nutrients.