MUSCLE PHYSIOLOGY

Detailed explanation-1: -The correct answer: For nerve and muscle cells, the inside of the cell is negatively-charged relative to the outside. In the nerve and muscle cells, there are potassium ions inside the cells and sodium ions present outside the cells.

Detailed explanation-2: -What generates the resting membrane potential is the K+ that leaks from the inside of the cell to the outside via leak K+ channels and generates a negative charge in the inside of the membrane vs the outside. At rest, the membrane is impermeable to Na+, as all of the Na+ channels are closed.

Detailed explanation-3: -Neurons actually have a pretty strong negative charge inside them, in contrast to a positive charge outside. This is due to other molecules called anions. They are negatively charged, but are way too big to leave through any channel. They stay put and give the cell a negative charge inside.