A decrease in the total amount of hemoglobin proteins or a lower-than-normal count of healthy red blood cells (RBCs).

is a critical medical condition characterized by the blood's inability to carry sufficient oxygen to tissues, despite the lungs having access to adequate oxygen and the heart being able to pump blood effectively. Unlike other forms of anoxia that may stem from environmental oxygen lack or mechanical blockage, anemic anoxia is fundamentally a failure of the blood's internal transport mechanism—primarily involving a deficiency or dysfunction of hemoglobin . The Mechanisms of Transport Failure

Situations where hemoglobin is present but cannot effectively bind to or release oxygen, such as in Carbon Monoxide Poisoning where CO occupies oxygen binding sites.

When the body detects falling oxygen levels due to anemia, it initiates several compensatory responses to maintain tissue viability: Anoxia Symptoms and Diagnosis - News-Medical.Net