What does the term 'hypoxia' refer to?

The term 'hypoxia' refers specifically to a deficiency of oxygen in the tissues. This condition occurs when the body or a specific area of the body does not receive sufficient oxygen supply, potentially causing cell damage and impairing organ function. Hypoxia can result from various physiological conditions such as respiratory diseases, carbon monoxide poisoning, or anemia, among others. When tissues do not have an adequate oxygen supply, they cannot perform their functions efficiently, which can lead to serious health consequences if not addressed promptly.

The other choices do not accurately represent the meaning of hypoxia. An increase of oxygen in the bloodstream indicates a state of hyperoxia, while excess carbon dioxide in the lungs relates more closely to conditions like hypercapnia. A decrease in blood circulation is linked to ischemia, which may lead to hypoxia but is not the definition of the term itself. Thus, the concept of hypoxia is specifically centered on the lack of oxygen availability to tissues.