The affinity for oxygen of ferric iron is impaired. The binding of oxygen to<unk> moglobin results in an increased affinity for oxygen in the remaining heme sites that are in ferrous state within the same tetrameric hemoglobin unit. This leads to an overall reduced ability of the red blood cell to release oxygen to tissues, with the associated oxygen–hemoglobin dissociation curve therefore shifted to the left. When<unk> moglobin concentration is elevated in red blood cells, tissue hypoxia may occur. Normally,<unk> moglobin levels are 2+) of the heme group of the hemoglobin molecule is oxidized to the ferric state (Fe3+). This converts hemoglobin to<unk> moglobin, resulting in a reduced ability to release oxygen to tissues and thereby hypoxia. This can give the blood a bluish or chocolate-brown color. Spontaneously formed<unk> moglobin is normally reduced (regenerating normal hemoglobin) by protective enzyme systems, e.g., NADH<unk> moglobin reductase (cytochrome-b5 reductase) (major pathway), NADPH<unk> moglobin reductase (minor pathway) and to a lesser extent the ascorbic acid and glutathione enzyme systems. Disruptions with these enzyme systems lead to<unk> . Hypoxia occurs due to the decreased oxygen-binding capacity of<unk> moglobin, as well as the increased oxygen-binding affinity of other subunits in the same hemoglobin molecule, which prevents them from releasing oxygen at normal tissue oxygen levels.
Methemoglobinemia
Argyria
Sulfhemoglobinemia
Heart failure
Hyperaemia
Hypoxemia
Organic acidemia
Hypercapnia