Question

In a normal healthy female, the number of RBC/mm cube of blood is
(a)6.5 - 7.0 million
(b)5.5 - 6.0 million
(c)4.5 - 5.0 million
(d)3.5 - 4.0 million

Answer 1

The primary function of the red blood cells, or erythrocytes, is to hold oxygen from the lungs to body tissues and to transfer carbon dioxide from the tissues to the lungs.

Complete answer:
Blood is a fluid animal tissue that consists of plasma, blood cells, and platelets. It circulates throughout our body delivering oxygen and nutrients to varied cells and tissues. Red blood cells (RBCs), also called erythrocytes, and are the most common type of blood cell. RBCs contain hemoglobin, which transports oxygen to the tissues. Women have about 4 to 5 million erythrocytes per microliter (cubic millimeter) of blood and men have about 5 to 6 million erythrocytes per microliter (cubic millimeter) of blood

Additional Information: Oxygen transfer is fulfilled through the hemoglobin carried in red blood cells. Hemoglobin combines readily with oxygen and carbon dioxide. Oxyhemoglobin in the blood reflects a bright red color while carboxyhemoglobin of blood appears red. The RBC is a count of the number of red blood cells per cubic millimeter of blood. In response to hypoxia, the hormone erythropoietin, secreted by the kidneys, stimulates the bone marrow to supply red blood cells. The formation of red blood cells is understood as erythropoiesis.
Normal red blood cells values at numerous ages are-
-Newborns: 4.8 - 7.2 million
-Adults: (males): 4.6 - 6.0 million
- Pregnancy: slightly lower than normal adult values
- Children: 3.8 – 5.5 million
So, the correct answer is '4.5 - 5.0 million'

Note: To enable the maximum oxygen saturation of hemoglobin, red cells are shaped like biconcave disks. The shape provides more area for exposure of hemoglobin to dissolved oxygen. Red blood cells also are ready to change form to allow passage through small capillaries that connect arteries with veins.