What is the job of the red blood cell…?
Red blood cells are the principal means of delivering oxygen to the body tissues via the blood. The cells are filled with hemoglobin, a biomolecule that can bind to oxygen. They take up oxygen in the lungs or gills and release it while squeezing through the body’s capillaries. Mammalian red blood cells are biconcave disks: flattened and depressed in the center, with a dumbbell-shaped cross section. This shape (as well as the loss of organelles and nucleus) optimizes the cell for the exchange of oxygen with its surroundings.
