The cell membrane is made of a “phospholipid bi-layer”, what that means is it has two layers of these special lipids. they have “heads” and “tails”. the head (circle structure) is adaptable and likes watery enviroments (hydrophilic). the head faces in cytoplasm of the cell, and the outside enviroment as well. the tails of the phospholipid are hydrophobic (afraid of water). they are made of fatty acids. along this membrane, there are several proteins and other molecules. some of these protists serve as “passageways” into the cell. molecules and chemicals can travel through the protein channel into the cell to be used. often there are also other molecules on the outside of the cell membrane to help receive and relay chemical messages, these come in the form of carbohydrate chain -hope this helped
During periods of maximum efforts the heart pumps blood at 34 liters per minute, and this delivers oxygen to the muscles at 4 liters per minute. But this is insufficient to meet the oxygen requirement of the muscles. The pancreas produces insulin that changes the glucose to glycogen to maintain the body.