Oxygen carrying capacity of blood is largely determined by

The O2 delivery system in the body consists of the lungs and the cardiovascular system. O2 delivery to a paicular tissue depends on the amount of O2 entering the lungs, the adequacy of pulmonary gas exchange, the blood flow to the tissue, and the capacity of the blood to carry O2. The blood flow depends on the degree of constriction of the vascular bed in the tissue and the cardiac output. The amount of O2 in the blood is determined by the amount of dissolved O2, the amount of hemoglobin in the blood, and the affinity of the hemoglobin for O2.Ref: Ganong review of medical physiology 23rd edition Page no: 609