Tetrodotoxin is a potent toxin found in a variety of organisms including the pufferfish. The toxin binds to the extracellular side of the Na channel and prevents channel opening. This leads to paralysis of muscles, including the diaphragm. Death from respiratory failure can occur after ingestion of as little as 1 mg of the toxin. Why does this toxin cause paralysis

At the cellular level, Tetrodotoxin blocks voltage-gated sodium channels, causing alterations in neuronal functions or nerve impulse resulting in paralysis.

Explanation:

Tetrodotoxin is a toxin that blocks sodium channels in cells, causing nerve numbness and muscle paralysis. To do this, the area of the guanidinium group, with a positive charge with a size similar to that of a hydrated Na + ion, binds to a negatively charged area of the channel, with a glutamate, and forces a change in the configuration of the constituent protein. By blocking sodium channels, tetrodotoxin produces paralysis of the muscles, causing death in a high number of chaos, around 50%, in a period between 20 minutes and eight hours.