What features of the vital activity of the external and internal structure of mammals

What features of the vital activity of the external and internal structure of mammals provide them with a constant body temperature?

Mammals are warm-blooded animals, that is, they have a constant body temperature. This is facilitated by the following features of the external and internal structure:
– 4-chambered heart, due to which venous and arterial blood does not mix;
– a layer of subcutaneous fat, which is a heat-insulating layer that retains heat in the body;
– hairline, which also prevents heat from leaving the body;
– sweat glands, which ensure the removal of excess heat and cooling of the body surface.