What is the importance and function of cytosol to the brain?

Answer 1

Cytosol is the fluid found inside cells and is the medium where cellular metabolism takes place. It has a slightly different composition to the fluid found outsides cells (extracellular fluid). In neurons, this difference in fluid composition is critical for cell signaling because it creates an electrochemical potential gradient across the cell membrane. When ions flux in and out of the cell (driven by chemical gradients and 'ion pumps') their charge alters the electrical potential difference across the cell membrane (i.e., think of the membrane as an insulator separating positive and negative charges). If enough positive charge enters a neuron then it will fire (release it's neurotransmitters).