Active or gated channels
–Chemically-gated
• NT binding causes channel to open
•found on dendrites and the cell body and open or close in response to the presence of neurotransmitters (ligands)
–Voltage-gated
•- open in response to ion flow (changes in membrane polarization)
•Have activation and inactivation gates that open and close differentially
•At rest the cytoplasmic sided inactivation gate is open and the extracellular sided activation gate is closed
• voltage-gated Na+ and K+ channels
•Voltage-gated Ca2+ channels are found at axon terminals
–Mechanically gated channels open when a membrane receptor is physically deformed.