What term is used for decreased oxygen supply to tissues?

The term for decreased oxygen supply to tissues is "hypoxia." Hypoxia specifically refers to an inadequate oxygen supply at the tissue level, regardless of the cause. This can occur even when there is sufficient oxygen in the bloodstream (hypoxemia), as hypoxia pertains to the level of oxygen available for cellular metabolism within the cells themselves.

While hypoxemia refers to low oxygen levels in the blood (often a precursor to hypoxia), it does not directly describe the condition of oxygen deficiency in the tissues. Ischemia, on the other hand, refers to insufficient blood flow to a tissue, which can lead to decreased oxygen supply, but it is not synonymous with hypoxia itself. Saturation pertains to the percentage of hemoglobin molecules bound to oxygen in the blood, which, while related to oxygen transport, does not directly define tissue oxygenation status.

Therefore, hypoxia is the most accurate term when discussing the deficiency of oxygen specifically within tissues, as it captures the essence of impaired cellular oxygenation.