So inside the brain, certain types of nerve cells don't actually use neurotransmitters to send action potential from one cell to another. Instead of using your transmitters, they actually use gap junctions. So on the presynaptic cell and the post synaptic cell, they're connected by these gap junctions. And that allows the quick movement of the action potential from one cell, the presynaptic neuron, to the other cell that postsynaptic neuron. Now let's move on to function number two, cell nourishment. So every single cell in our body needs things like glucose, amino, amino acids, nucleotides, to actually survive and function correctly.