Researchers are looking into how stimulation with neurotransmitters affects the membrane potential of postsynaptic neurons. Baseline experiments show that high membrane permeability for a certain ion generates the resting membrane potential. In response to the onset of neurotransmitter stimulation, ligand-gated ion channels open (black arrow) and enhance the membrane's permeability for an alternative ion, altering the membrane potential. This causes voltage-gated ion channels (red arrow) to open slowly, increasing the permeability of the membrane for a third kind of ion. The graph below displays the experiment's findings. The equilibrium potentials of different ions under physiologic conditions are as follows: Which of the following options would best explain the changes in this neuron's membrane potential during the experiment?

Question

Researchers are looking into how stimulation with neurotransmitters affects the membrane potential of postsynaptic neurons. Baseline experiments show that high membrane permeability for a certain ion generates the resting membrane potential. In response to the onset of neurotransmitter stimulation, ligand-gated ion channels open (black arrow) and enhance the membrane's permeability for an alternative ion, altering the membrane potential. This causes voltage-gated ion channels (red arrow) to open slowly, increasing the permeability of the membrane for a third kind of ion. The graph below displays the experiment's findings.

The equilibrium potentials of different ions under physiologic conditions are as follows:

Which of the following options would best explain the changes in this neuron's membrane potential during the experiment?

Quizplus · Accepted Answer

Eductional Objective: Cellular ions' equilibrium potentials represent how they would influence the membrane potential if that ion were the only one that could pass through the membrane. The graph's negative resting membrane potential indicates that an ion with a negative equilibrium potential can pass through the membrane when it is at rest (potassium or chloride). When a neurotransmitter binds, ligand-gated ion channels open in response (black arrow), raising the membrane potential above zero. This shows that an ion with a positive equilibrium potential has made the membrane permeable (sodium or calcium). The membrane potential decreases as a result of opening voltage-gated ion channels in response to the altered membrane potential (red arrow), demonstrating that the membrane is now permeable to an ion with a negative equilibrium potential.

Researchers Are Looking into How Stimulation with Neurotransmitters Affects the Membrane