Final answer:
A polarized neuron has a negatively charged interior due to the higher concentration of positive ions outside and selective permeability of its membrane, resulting in a resting membrane potential.
Step-by-step explanation:
When discussing neuronal function, it’s important to understand the resting membrane potential. A polarized neuron indeed has fewer positive ions inside in comparison to the outside. At rest, the neuron's interior is roughly 70 millivolts more negative than the exterior, a state known as the resting membrane potential, primarily a result of varying ion concentrations on either side of the neuron's membrane.
Potassium ions (K+), while more abundant inside, freely exit the neuron through potassium channels, contributing to the net negative charge inside. Conversely, sodium ions (Na+), which are present in higher concentrations outside the neuron, enter more slowly due to a fewer number of sodium channels. These ionic movements are further reinforced by the sodium-potassium pump, which uses ATP to maintain the ionic imbalance across the membrane by expelling more sodium than it admits potassium, thereby preserving the negative charge within the neuron.