Membrane transport in organ systems

Selective permeability allows the cell to have control over which molecules cross the membrane. This helps maintain homeostasis in the cell. In multicellular organisms like humans, individual cells work together in tissues, organs and organ systems to keep the whole organism alive and healthy. Most cell types are highly specialized and express proteins, including transport proteins, to fit their needs. The correct expression and function of transport proteins are therefore not only essential for the cell itself, but also for the tissue or organ this cell is part of and ultimately the health of the whole organism. There are many examples of membrane transport in organ systems. Some examples include the transport of ions to send electrical signals in nerves, transport of waste products into urine and reabsorption of useful molecules into the blood in the kidneys and transport of calcium in to and out of the cell in skeletal and cardiac muscle.