Erythrocytes are formed in the red bone marrow, live up to 120 days, have the shape of a double-curved disc, are elastic, which allows them to easily pass through the capillaries; non-nuclear, since the entire volume of a mature cell is occupied by hemoglobin, an iron-containing protein that freely binds to oxygen; the membrane allows oxygen to pass freely. Red blood cells carry oxygen and carbon dioxide in tissues.
Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.