Question

The venom of the green mamba carries dendrotoxin, which partially blocks voltage gated K+ channels in neutral axons. What effect would this venom have on an action potential?

a. It would prolong action potentials
b. It would decrease the membrane depolarization during action potentials
c. The axon would never recover its resting potential once stimulated
d. It would prevent action potentials from occurring
e. It would substantially raise the threshold voltage for action potentials

Answer 1

The green mamba's dendrotoxin blocks K+ channels, prolonging the action potentials by delaying repolarization as K+ ions cannot leave the neuron quickly.

Step-by-step explanation:

The venom of the green mamba carries dendrotoxin, which partially blocks voltage gated K+ channels in neuronal axons. During the action potential, sodium (Na+) channels open to depolarize the membrane and potassium (K+) channels subsequently open to repolarize the membrane, returning to the resting potential. If dendrotoxin inhibits the function of K+ channels, the repolarization phase of the action potential would be prolonged. This means that the neuron would take longer to return to its resting state after an action potential has occurred.

Option a, 'It would prolong action potentials' is the correct effect that the green mamba venom would have on an action potential. When K+ channels are blocked, there is a delay in repolarization, because K+ ions cannot leave the cell as quickly as they should. This extension in duration of the action potential could affect the timing of subsequent action potentials and potentially lead to continuous depolarization if other compensatory mechanisms do not intervene.