Glossary of Physiology Terms
There are
9 glossary search results for:
Voltage gated channel
Definition:
An integral membrane protein which contains a pore through which ions, water, or polar molecules permeate. For any given channel, the pore is usually very selective for the particular ion or molecule. For example, sodium (Na
+) channels are very selective for Na
+ over other cations.
The channel pore may be constitutively open, or it may be gated to the open state by various stimuli such as chemical ligands, voltage, temperature, or mechanical stimulation of the membrane.
Definition:
The Hodgkin cycle represents a positive feedback loop in neurons, where an initial membrane depolarization from the resting value (∼ −70 mV) to the threshold value (∼ −50 mV) leads to rapid depolarization of the membrane potential to approach the equilibrium potential for Na
+ (
VNa ≈ +60 mV). The voltage-gated Na
+ channels of neurons are responsible for the Hodgkin cycle.
See the
figure depicting the Hodgkin cycle.
See also:
Important Features of the Neuronal Action Potential
Definition:
Lidocaine is a local anesthetic and an antiarrhythmic drug. It is a commonly used local anesthetic for minor surgery and in dental procedures. Lidocaine is also used topically to relieve itching, burning, and pain from skin inflammations.
Lidocaine's mechanism of action is to block fast voltage-gated Na
+ channels of neurons and cardiac myocytes.
Other names used for lidocaine are xylocaine and lignocaine.
See also:
Pharmacological Inhibition of Na+ and K+ ChannelsOther resources:
Lidocaine (Wikipedia)
Definition:
Neurotoxins are chemical molecules that have an adverse effect on neuron function and, thus, disrupt the normal function of the nervous system. Neurotoxins could be small molecules or peptides and can be derived from a variety of invertebrate and vertebrate animals, as well as plant species.
The following is a short list of some examples of neurotoxins:
α-Bungarotoxin: A peptide neurotoxin that inhibits the nicotinic acetylcholine receptor.
Chlorotoxin: A peptide neurotoxin that inhibits chloride channels.
α-Conotoxin: A peptide neurotoxin that inhibits the nicotinic acetylcholine receptor.
δ-Conotoxin: A peptide neurotoxin that inhibits voltage-gated sodium channels.
w-Conotoxin: A peptide neurotoxin that inhibits N-type voltage-gated calcium channels.
Picrotoxin: Inhibits GABA
A receptor chloride channels.
Tetrodotoxin: Inhibitor of neuronal voltage-gated sodium channels.
Abbreviation:
TEA
Definition:
An inhibitor of voltage-gated potassium (K
+) channels.
TEA is a quaternary ammonium
cation (positively charged ion). It is also commonly used as a cation replacement for sodium (Na
+) in physiological buffers used in ion replacement experiments.
See also:
Pharmacological Inhibition of Na+ and K+ Channels
Definition:
The membrane voltage that must be reached in an excitable cell (e.g., neuron or muscle cell) during a depolarization in order to generate an action potential. At the threshold voltage, voltage-gated channels become activated. Threshold is approximately −50 to −40 mV in most excitable cells.
Related glossary terms/phrases:
Sub-thresholdSupra-thresholdSee also:
Neuronal Action Potential - Introduction
Posted: Sunday, March 31, 2013
Last updated: Friday, August 28, 2015