The red cells, technically known as erythrocytes, are concerned with the transport of oxygen from the lungs to the tissues where it is required. They arc tiny discs with a depression in the middle. They can be readily detected under the microscope.
In normal health, there are between 4.5 and 6.5 million million in each liter of blood in males. (This is written down by a doctor as 4.5 and 6.5 x 1012/L.) In females the figure is 3.9 and 5.6 x 1012/L.
The important ingredient of the red cell is a chemical called hemoglobin, for this substance readily collects oxygen in the lungs, discharging it at the cells to which it is conveyed through the circulation. It is possible by a simple test, to measure the hemoglobin content of the blood.
Normally, this ranges between 135 and 180 grams per liter of blood in males, and between 115 and 165 grams in females. Once the blood becomes deficient in hemoglobin and the level drops to below what is recognized as normal, symptoms start to appear, and the person is said to be anemic.