Question

Tetrodotoxin is a toxin that blocks voltage-gated sodium channels. What effect does this substance have on the function of neurons?

A) Neurons depolarize more rapidly.
B) Action potentials lack a repolarization phase.
C) The absolute refractory period is shorter than normal.
D) The neuron is not able to propagate action potentials.
E) The toxin does not interfere with neuron function because the voltage-regulated sodium channels would still function.

Answer 1

Tetrodotoxin blocks voltage-gated sodium channels, preventing the depolarization necessary for action potential propagation, thereby inhibiting neuronal activity.

Step-by-step explanation:

Tetrodotoxin is a toxin that blocks voltage-gated sodium channels. The effect of this substance on the function of neurons is that it prevents the depolarization phase of an action potential, meaning that the neuron is not able to propagate action potentials.

During a normal action potential, voltage-gated Na+ channels open in response to a depolarizing stimulus, allowing Na+ ions to enter the neuron and further depolarize the membrane. This depolarization is essential for the propagation of action potentials along the neuron. When tetrodotoxin blocks these channels, Na+ ions cannot enter the neuron, and the action potential cannot occur, effectively silencing neuronal activity.