Answer:
Gas exchange between tissues and the blood is an essential function of the circulatory. The air contains oxygen that crosses the lung tissue, enters the bloodstream, and the alveoli are in direct contact with capillaries of the circulatory system. As water flows over the gills, oxygen is transferred to blood via the veins.
Explanation:
Obese humans probably have high levels of leptin because the brain does not respond to leptin, so they keep eating despite adequate (or excessive) fat stores
The two major fluid is intracellular and extracellular
Animals have Mitochondria that use the sugars provided by plants to produce their own cellular energy :)
