Passive transport has 3 concepts to it.. these include: diffusion, facilitated diffusion and osmosis. All 3 of these are when a solution goes from an area of high concentration to an area of low concentration. All three of these are how substances move in and out of cells. Active transport refers to a substance going from an area of low concentration to an area of high concentration. The three of these include: plasma membrane in relation to calcium and potassium, endocytosis, and extocytosis. The function of these three is to also bring substances from an area of high concentration to an area of low concentration. Membrane pumps do this by bringing the high concentration to inside the cell so the potassium and calcium switch spots. With endocytosis and extocytosis, endocytosis brings items into the cell by digesting (phagocytosis) and drinking them (pinocytosis); extocytosis almost pushes away the cell and that’s how it gets across the membrane
