The conduction of a nerve impulse is ....

During resting potential,the axonal membrane is more permeable to.........

The state in which the axonal membrane is positively charged on the outside and negatively charged on the inside is known as:

During the transmission of a nerve impulse,which of the following events occurs?

Give scientific reasons:
$(1)$ There is no physical connection between sequential neurons,yet nerve impulses are conducted through them.
$(2)$ The neuroplasm of a neuron contains a high $K^+$ concentration during the maintenance of the resting potential.

For visual sense,the nerve impulse is generated by