Who can briefly talk about the working principle of hemoglobin transporting oxygen?

Hemoglobin is one of the structures of red blood cells.

1 hemoglobin is a four-level structure in protein, with four subunits, each of which has a hydrophobic part, and can bind 1 molecular oxygen and 1 molecular hemoglobin, so 1 molecular hemoglobin can bind four molecular oxygen.

In the lungs, venous blood inhales oxygen, hemoglobin combines with oxygen, and blood becomes arterial blood, which flows to the heart and is transported to all parts of the body through the beating of the heart. Hemoglobin releases oxygen into tissues through complex mechanisms.