Hemoglobin (Hb)

Hemoglobin binds to oxygen and carbon dioxide in the blood stream.

Oxygen Affinity

Hemoglobin's affinity for O\(_2\) is mediated by temperature and pH.

Oxygen affinity is higher in colder, basic environments such as the lungs, making hemoglobin more likely to bind with oxygen during respiration.

Oxygen affinity is lower in warmer, acidic environments such as skeletal muscle (and particularly during exercise, where body temperatures rise and skeletal muscle produces lactic acid in response to exercise-induced hypoxia), making hemoglobin more likely to release oxygen in response to demand.