In chronic hypoxemia, which two substances increase?

Prepare for the Respiratory CAS Exam with comprehensive quizzes. Utilize flashcards and multiple choice questions, each crafted with detailed explanations and hints. Equip yourself for success in your test!

Chronic low oxygen levels trigger two main adaptations to improve oxygen delivery. Erythropoietin, produced by the kidneys, increases and drives erythropoiesis, raising the red blood cell mass and hemoglobin level so more oxygen can be carried in the blood. At the same time, red blood cells accumulate more 2,3-bisphosphoglycerate, which binds to deoxygenated hemoglobin and lowers its affinity for oxygen. This shifts the oxyhemoglobin dissociation curve to the right, promoting easier unloading of oxygen to tissues that are starved of it.

Together, these changes enhance tissue oxygenation during ongoing hypoxemia, though the higher red cell mass can raise blood viscosity. Hemoglobin increases as a result of the erythropoietic response, but the substances that actively drive this adaptation are erythropoietin and 2,3-BPG. Carbon dioxide and nitric oxide don’t rise in this universal compensatory way for chronic hypoxemia.