Question

In man, the number of R.B.C. per cubic mm of blood is
A. 1 to 3 million
B. 5 to 5.4 million
C. less than one million but more than 50,000
D. less than 50,000

Answer 1

Hint: RBC is the major formed element (blood cells) of blood. RBCs play a major role in the transport of respiratory gases.

Complete Answer:
Blood is a connective tissue in fluid form. Blood contains the blood cells which are called formed elements and the liquid portion is known as plasma.
Plasma: Plasma is a straw-colored clear liquid part of blood. It contains 91%- 92% of water and 8%-9% of solids.
Blood Cells: Three types of cells are present in the blood:
1. Red blood cells or erythrocytes
2. White blood cells or leukocytes
3. Platelets or thrombocytes.

Red Blood Cells: Red blood cells (RBCs) are the non-nucleated formed elements in the blood. Red blood cells are also known as erythrocytes (erythros = red).
- The red color of the red blood cell is due to the presence of the coloring pigment called hemoglobin.
- RBCs play a vital role in the transport of respiratory gases. RBCs are more in number as compared to the other two blood cells, namely white blood cells and platelets.
- The normal value of RBC count ranges between 4 and 5.5 million/cubic mm of blood. In adult males, it is 5-5.5 million/cubic mm and in adult females, it is 4.5-5.5 million/cubic mm.

So, the answer is B. In man, the number of RBC per cubic mm of blood is 5 to 5.4 million.

Note: Increase in the RBC count is known as Polycythemia. A decrease in the RBC count is known as Anaemia.