The difference in charge between the inside and outside of an axonal membrane is generated by what 3 forces?

1, High membrane permeability to potassium.

Which results from high number of  potassium ion channels along the axon membrane compare to other ions. Therefore more potassium ions  diffuse easily out of the axoplasm  caring its positive ions  along into the extracellular layer, making the inside (axoplasm) deficient in positive   charge  therefore more negative compare to the outside . Thus the inside  of the axon is more negative than the outside layer.

2. Strong  chemical gradient for potassium.

Basically,the  inside of the cells is made up of more positively charged potassium ions, and  some negatively charged anions.

However the strong chemical gradient  allows continuous diffusion of potassium ions  from the axoplasms into the outside layer. This occurs because of higher distribution of the positively charge potassium ions(high chemical gradients) of  the inside compare to outside, therefore more positively charge ions  potassium move out of the axopasm making the inside negative, (with already  negatively charged anions present in the inside compare to extracellular layer)

3. High Electrochemical gradients.

Basically the inside of axons  has more potassium ions, while the outside has more sodium ions in a neuron at rest.

The electrochemical gradients  results from the combination of high negatively charges  of anions inside the axoplasms,and the high concentration  gradients of  positively charged sodium ions outside the axon. The combination of these two forces called Electrochemical gradients pull sodium ions from the outiside with its positive charges  into the  negatively charged  medium (inside) axoplasm. Creating reversal of charges; thus the inside is now more positive while the outside is  negative.

Explanation: