Ligand Gated Ion Channels

Pharm

Ion Channel

________

Transmembrane protein that allows selective ion movement across cell
membranes down electrochemical gradients, enabling rapid electrical signaling

Electrochemical gradient

_____
The combined effect of an ion’s concentration gradient and electrical gradient
that drives ion movement.

Selectively

_______
The ability of an ion channel to preferentially conduct specific ions based on size, charge, and hydration shell.

Conductance

______

The ease with which ions pass through an open channel

Permeability

______
The relative ability of different ions to pass through a channel

Gating

_______

The process by which ion channels open or close in response to stimuli.

Closed State

________

Channel is non-conductive but capable of opening.

Open State

_______
Channel conducts ions through the pore

Inactivated/Desensitized

________
Channel is non-conductive despite the continued presence of ligand and must
recover before reopening

Channel Kinetics

_________
The timing properties of channel opening, closing, and recovery that shape
neural signaling.

Ligand Gated Ion channel

_______

Ion channel that opens when a specific chemical ligand (e.g., neurotransmitter)
binds

Voltage Gated Ion Channel

________
Channel that opens in response to changes in membrane potential

Leak Channel

________
Constitutively open channel that helps establish resting membrane potential

Mechanically Gated Channel

________
Channel activated by physical deformation such as stretch or pressure.

Graded Postsynaptic Potential

________

Variable-amplitude membrane potential change proportional to the number of
open LGICs

Action Potential

_______

All-or-none electrical signal generated by VGICs once threshold is reached

Excitatory Postsynaptic Potential

_________
Depolarizing graded potential typically produced by Na⁺ or Ca²⁺ influx

Inhibitory Postsynaptic Potential

__________
Hyperpolarizing or stabilizing graded potential typically produced by Cl⁻ influx

Modulation

________
Alteration of channel behavior (opening probability, duration, sensitivity) without
permanent blockade

Blockade

__________
Prevention of ion flow through a channel, often associated with toxicity if
complete

Affinity

________
Strength of drug–receptor binding (quantified by Kd).

Efficacy

________
Maximum effect a drug can produce once bound (Emax).

Potency

_________
Amount of drug needed to produce a given effect (EC₅₀)

Orthosteric site

________
Primary ligand-binding site on a receptor

Allosteric site

________
Secondary site where modulators alter receptor response without directly
activating it.

Competitive antagonist

_______
Competes with ligand at the orthosteric site; reduces potency, not efficacy

Noncompetitive antagonist

________
Binds a distinct site; reduces maximal efficacy

Multimeric Channel

__________

Ion channel composed of multiple subunits forming a central pore

Extracellular domain

_________
Contains ligand-binding sites.

Transmembrane Domain

________
Forms the ion-conducting pore and determines ion selectivity

Intracellular Domain

_________

Regulates trafficking, phosphorylation, and modulation

Channelopathy

___________

Disease caused by dysfunctional ion channel structure or regulation

Excitotoxicity

_______

Neuronal injury caused by excessive excitatory ion flux, especially Ca²⁺.