Question

The TLC of human blood is about:
a. 5000-6000 per ml of blood
b. 5000-10000 per ml of blood
c. 5000-11000 per cubic mm of blood
d. 2000-6000 per cubic mm of blood

Answer 1

Blood is the connective tissue that supplies the oxygen to the various parts of the body. Along with supply of oxygen, blood also has various other cell components which play a major role in regulation, providing immunity and maintaining homeostasis.

Complete answer:
Blood is a fluid connective tissue which runs throughout the body. The components of blood include plasma, red blood cells, platelets and white blood cells.
Plasma is the liquid part of the blood containing 90% water and remaining 10% organic molecules, ions, gases, nutrients and waste materials. Plasma primarily maintains the pH balance and osmotic pressure of blood.

Red blood cells are one of the cellular components and play the role of supplying the oxygen to the various parts of the body. Their life span is about 120 days and after their completion of life span these are destroyed or degraded in liver or spleen, simultaneously new ones are produced in bone marrow. The normal RBC count in human is 4.2 to 6 million cells per microlitre.

Platelets are the cell components used in blood clotting. It gets activated when there is any breakage in blood vessel. It helps in formation of platelet plug and aids the process of blood clotting.

White blood cells are the cells that are responsible for providing immunity and constitute about 1% of the blood having normal count as 4500- 11000 cells per microlitre. These are of following types:

Granulocytes: These include the cells that contain small granules in them these are further classified as basophils (released during allergic reactions), eosinophils (produce general immune and inflammatory response) and neutrophils (usually surround and kill bacterias when encountered).
Lymphocytes: These cells are responsible for causing immune response in the body. The normal TLC (total lymphocyte count) in humans ranges from 4000-11000 cells per microlitre of blood. Lymphocytes include B-lymphocytes, T-lymphocytes and natural killer (NK) cells.
Monocytes: These are the cells that get activated during chronic infections in the body. They target and destroy the cells that cause infection.

Hence, the correct answer is option (B).

Note: The main functions of the blood include the supply of oxygen to the cells, providing nutrition, removing wastes from tissues, protecting the body from infectious agents, regulation of pH levels and temperature of the body and transmission of signals via hormones and regulators.