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What is Why is the oxygen-hemoglobin dissociation curve sigmoid is shape? and explain in detail?
Oxygen hemoglobin dissociation curve, is the curve relating percentage saturation of the oxygen carrying power of hemoglobin to the Po2. It has a characteristic sigmoid shape due to the T-R interconversion. In deoxyhemoglobin, globin units are tightly bound in a tense (T) configuration which reduces the affinity of the molecule for oxygen. When the first oxygen is bound, the bonds holding the globin units are released, producing a relaxed (R) configuration which exposes more oxygen binding sites. Thus, binding of one oxygen molecule increases the affinity of hemoglobin to bind other O2 molecules. Ref: Review of Medical Physiology, 22nd Edition By William F Ganong, Pages 667, 669; Textbook of Medical Physiology By Khurana, Page 440; Textbook of Physiology By Guyton and Hall, 10th Edition, Page 475