Final answer:
TTX blocks voltage-gated Na+ channels in a reversible manner, making the statement False. Continuous conduction along unmyelinated axons relies on these channels for action potential propagation.
Step-by-step explanation:
The statement that TTX irreversibly blocks voltage-gated sodium channels in axonal membranes is False. Tetrodotoxin (TTX) is known to be an extremely potent blocker of voltage-gated Na+ channels, but its action is reversible, not irreversible. These channels are crucial for the propagation of an action potential along axons, particularly in continuous conduction along unmyelinated axons. When TTX binds to these sodium channels, it prevents the influx of sodium ions, thus inhibiting the rise of the action potential. However, after the removal of TTX, the sodium channels can recover their function.
Continuous conduction refers to the slow propagation of an action potential along an unmyelinated axon, due to the presence of voltage-gated Na+ channels situated throughout the entire axonal membrane. This is in contrast to saltatory conduction in myelinated axons, where the action potential jumps from node to node, speeding up signal transmission.