Oxygen–hemoglobin dissociation curve the fluid that surrounds it. Hemoglobin (Hb) is the primary vehicle for transporting oxygen in the blood. Oxygen is also carried dissolved in the blood's plasma, but to a much lesser degree. Hemoglobin is contained in red blood cells. Under certain conditions, oxygen bound to the hemoglobin is released into the blood's plasma and absorbed into the tissues. Each hemoglobin molecule has the capacity to carry four oxygen molecules. These molecules of oxygen bind to the iron of the Heme group. The binding of the first oxygen molecule induces a conformational change of hemoglobin that increases the affinity for the
Blood volume Blood volume Blood volume is the volume of blood (both red blood cells and plasma) in the circulatory system of any individual. A typical adult has a blood volume of approximately 5 liters, with females and males having approximately the same blood volume. Blood volume is regulated by the kidneys. Blood volume (BV) can be calculated given the hematocrit (HC; the fraction of blood that is red blood cells) and plasma volume (PV), with the hematocrit being regulated via the blood oxygen content regulator: Blood volume measurement may be used in people with congestive heart failure, chronic hypertension, renal failure