What ion is responsible for depolarization of the neuron during an action potential?

Answer 1

No single ion in and of itself is responsible for firing an action potential. Instead, 4 total ions are important when talking about excitable cells in general. These include sodium, potassium, calcium, and to a very small extent, chlorine. (chlorine has a role in excitable cells while they are at rest, but not while they are firing action potentials) Sodium and potassium are the main ions involved in changing the membrane potential of an excitable cell, which leads to the firing of an action potential. However, calcium ions are also important in the process. Calcium ions allow vesicles (these are essentially containers of small molecules and ions in the cell) at the end of a cell body to fuse with the cell membrane and release their contents into the outside environment. In this outside environment, the released contents bind with certain receptors on a neighboring cell, which is then depolarized, generating a new action potential. (this is called propagation)

Answer 2

Na+ entering the cell through voltage gated sodium channels depolarises the neurone so AP can occur. Technically other stimuli such as synaptic transmition cause depolarisation to open voltage gated Na+ channels but Na+ would be what you are looking for.

Answer 3

Usually repolarization phase is the attaining of resting membrane potential (having more negative value of charge inside the membrane than outside of it)back from action membrane potential (having more positive charge inside the membrane than outside the cell).

It occurs from the movement of positively charged potassium ions out of the membrane (cell).

Answer 4

Sodium ions are responsible for depolarizing the neuron during an action potential. When a neuron is stimulated, sodium channels open, allowing sodium ions to flow into the cell, making the inside more positive.

Answer 5

calcium