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Glossary of Physiology Terms
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Definition:
Supra-threshold (or suprathreshold) refers to a stimulus that is large enough in magnitude to produce an action potential in excitable cells.

In general, a supra-threshold stimulus leads to the depolarization of the membrane, and the magnitude of the depolarization is larger than that necessary to simply reach the threshold voltage. Therefore, supra-threshold stimuli elicit action potentials.

Related glossary terms/phrases:
Threshold
Sub-threshold

See also:
Neuronal Action Potential - Introduction



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 GABAA receptor chloride channels.

Tetrodotoxin: Inhibitor of neuronal voltage-gated sodium channels.









Posted: Sunday, March 31, 2013
Last updated: Friday, August 28, 2015