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 is a toxin that blocks voltage-gated sodium channels. D. The neuron is not able to propagate action potentials.

Step-by-step explanation:

Tetrodotoxin, derived from pufferfish and some other marine organisms, blocks voltage-gated sodium channels in neurons. These channels are crucial for the initiation and propagation of action potentials. When exposed to tetrodotoxin, these channels are inhibited, preventing the influx of sodium ions that is essential for the rising phase of an action potential.

Firstly, the blockage of sodium channels means that the neuron cannot depolarize adequately, hindering the initiation of action potentials. Secondly, without the influx of sodium ions, the neuron is unable to generate the necessary positive charge for the action potential to propagate along the axon. This leads to the absence of action potentials, effectively disrupting neuronal communication.

In conclusion, option D is the correct choice. Tetrodotoxin's interference with voltage-gated sodium channels results in the neuron's incapacity to propagate action potentials. This disruption in neural signaling can have severe consequences, affecting various physiological processes and highlighting the importance of functional sodium channels in maintaining normal neuronal function.