This chapter discusses neuroglia, which is the equivalent of connective tissue cells in the nervous system. In support of the hypothesis, glutamate, a common neurotransmitter, releases arachidonic acid from the plasma membrane into the astrocytes. Astrocytes may sense neuronal activity, and induce hyperemia in regions where the activity is high. The fibrous types of astrocytes are associated with nerve fibres while the protoplasmic type are associated with cell bodies of neurons, dendrites and synapses. During intense neuronal activity, it is likely that potassium ion concentration in the extracellular fluid might rise so high as to impair neuronal function. The astrocytes are likely to be involved in healing and repair of injury in the nervous system. During intense neuronal activity, it is likely that potassium ion concentration in the extracellular fluid might rise so high as to impair neuronal function. Neuroglia might supplement the meagre interstitial fluid in the brain.