The answer is all of these
The connective tissues of mammalian brain is called the meninges. There are three layers of this tissue. The outer layer is called the dura mater. The arachnoid is the middle layer and the pia mater is the inner layer of it.
Sodium, potassium, chloride and calcium ions are important for establishing the resting potential of the cell. The sodium-potassium gradient is maintained by a pump which transports 2 potassium inside the cell and 3 sodium ions outside the cell.
