answer: 1:In fact, hemoglobin is composed of four globin proteins—two alpha chains and two beta chains—each with a heme group. The heme group contains one iron atom, and this can bind one molecule of oxygen. Because each molecule of hemoglobin contains four globins, it can carry up to four molecules of oxygen.
2:It is the iron atom that binds oxygen as the blood travels between the lungs and the tissues. There are four iron atoms in each molecule of hemoglobin, which accordingly can bind four molecules of oxygen.
3:Human red blood cells are sometimes suggested as an exception to the cell theory because they have no nucleus, but nuclei are present as they form, and red blood cells of other animals do have nucleis.The biconcave shape of the cell allows oxygen exchange at a constant rate over the largest possible area. ... Learn about red blood cells (erythrocytes) by watching them move through arteries and capillaries. As the cells move through the capillaries, they deliver oxygen to the surrounding tissues.
4:The major cell types are the epithelial type I and type II cells, the pulmonary endothelial cells, interstitial cells, and macrophages. Type I cells constitute 8–11% of all cells found in the alveolar region and type II epithelial cells constitute 13–16%.
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