Question

The number of RBC in an adult man per ${ mm }^{ 3 }$ of blood is
(a)5000
(b)50,000
(c)500,000
(d)5,000,000

Answer 1

Hint: The red bone marrow of our body produces approximately 2.4 million new RBCs per second that circulates for nearly 100- 120 days. The number of cells consisting of a human body is 70% red blood cells.

Complete answer:
The RBC count in an adult man per ${ mm }^{ 3 }$ of blood is 4,600,000- 5,000,000. In females, the count is 4,200,000- 5,000,000 per cubic mm of blood. The count also varies in different ages. In newborns, it is the highest i.e. 4.8- 7.2 million and in children 3.8-5.5 million per cubic mm of blood.

Additional Information:
Let us know more about red blood cells or red blood corpuscles (RBC):
-These are the principal means for oxygen transportation in our body via blood flow in the circulatory system.
-The cytoplasm of RBC stores hemoglobin that can bind with oxygen and carry it around as well as gives the blood its red color.
-These are biconcave disc-shaped cells that do not contain a nucleus and most of the organelles to keep enough space for the hemoglobin molecules.
-The red bone marrow of our body produces these cells in a large quantity (2.4 million new cells per second) and after 100-120 days they get recycled in the spleen.
-Adult humans carry 20-30 trillion RBCs at a time which constitutes nearly 70% of all cells by number.
-Certain diseases may alter the number of RBC in the blood such as Anemia, hemolysis, etc.

So, the correct answer is ‘5,000,000’.

Note: The process of red blood cell production in red bone marrow is known as erythropoiesis by which the cells develop from stem cells to mature red blood cells and it takes about 7 days. This process is stimulated by the EPO hormone. The aged blood cells, later on, get removed from the blood by the spleen, liver, or lymph nodes. The average lifespan of these cells is considered to be 120 days.