In electrophysiology, the movement of ions such as Na+, K+ and Ca++ across cell membranes is called "ion transport". Ion transport makes possible the control of heart muscle contraction and rapid long distance electrical signals (action potentials) in the nervous system.
Ion transport is made possible by ion transport proteins. Ion transport proteins facilitate the movement of cations and anions across lipid bilayer membranes.
Examples:
The Na+,K+ pump uses the energy of ATP to move sodium out of cells and potassium into cells.
The "funny channel" is an ion channel protein that allows sodium ions to enter heart pacemaker cells. This initiates cardiac action potentials and the heart beat.
Textbooks:
Carrier Proteins and Active Membrane Transport and Ion Channels in Molecular Biology of the Cell
Ion Transport in The Cell: A Molecular Approach