Final answer:
The membrane potential is influenced by two primary factors: the chemical force due to the ions' concentration gradient, and the electrical force due to the charge difference across the membrane.
Step-by-step explanation:
The two factors that influence the membrane potential are the chemical force (concentration gradient of ions) and the electrical force (effect of the membrane potential on the ions' movement). The chemical force is caused by the differential concentration of ions across the membrane, leading ions to move from regions of high concentration to regions of low concentration. On the other hand, the electrical force is due to the electric charge differential across the membrane that affects the movement of ions according to the charge; like charges repel and opposite charges attract. These forces together create what's known as an electrochemical gradient.