Exam 3 Review:  Chapter 11:  Ion Channels  

ion channel - An integral membrane protein which is a pathway for movement of charged particles through a cell membrane facilitated by integral membrane proteins which have selective water-filled conductive channels that permit or exclude passage of charged particles based on size and charge; these pathways may be gated and regulated or nongated and always open or leaky.

leakage (ion) channel = nongated (ion) channel - An integral membrane protein which is an ion channel within a cell's outer cell membrane which is always open and permits the diffusion of one or more ions in the direction which is in accord with their concentration and charge gradients.

gated (ion) channel - An integral membrane protein which is an ion channel within an excitable cell's outer cell membrane which opens and closes in response to some stimulus, e.g., membrane potential (voltage) changes, the arrival and binding of a specific ligand or signal molecule (hormone, neurotransmitter, local hormone) or to mechanical pressure or to light energy.

voltage gated (ion) channel - An integral membrane protein which is an ion channel within an excitable cell's outer cell membrane which opens and closes in response to a stimulus which is a change in membrane potential (voltage) [i.e., a change in local membrane charge from negative to positive or vice versa] nearby in the membrane; such channels are primarily responsible for the depolarization events of nerve impulse conduction = propagation in excitable cells such as neurons, muscle cells, and gland cells.

chemically gated (ion) channel - An integral membrane protein which is an ion channel within an excitable cell's outer cell membrane which opens and closes in response to a stimulus which is the arrival and binding of a specific ligand or signal molecule (hormone, neurotransmitter, local hormone); such channels are primarily responsible for impulse initiation = initial depolarization of an excitable cell such as neurons, muscle cells, and gland cells.

mechanically gated (ion) channel - An integral membrane protein which is an ion channel within an excitable cell's outer cell membrane which opens and closes in response to a stimulus which is a mechanical pressure or vibration; such channels are primarily responsible for impulse initiation = initial depolarization of an excitable cell such as a mechanoreceptor (sensory cell responding to touch, vibration, compression or stretch).

light-gated (ion) channel - An integral membrane protein which is an ion channel within a photosensitive excitable cell's outer cell membrane which opens in response to a stimulus which is the arrival of a photon of light energy; such channels are primarily responsible for impulse initiation = initial depolarization of an excitable cell such as a photoreceptor (sensory cells, rods and cones responding to light in the retina of the eye).

List:

6. The two basic types of ion channels and define the difference in regulation between them.

7. Four types of gated channels based on the stimulus type which triggers opening or closing.

          voltage gated (ion) channel, chemically gated (ion) channel, mechanically gated (ion) channel, light-gated (ion) channel