Cells must move materials through the {membrane} and throughout the {cytoplasm} to maintain {homeostasis} Movement of substances is regulated because membranes are {semi} permeable. Membranes are {phospholipid} bilayers that contain embedded {proteins} The cells external environment and cytoplasm are aqueous, meaning that solutes such as {salt}are dissolved in a solvent called {water} Water may travel slowly through the membrane by {osmosis} or quickly through protein channels called {aquaporins}
