Define the term Synapse. How are Cytons and Axons of neurons placed in the Cerebrum?

A SYNAPSE is the junction between the axon endings of one neuron and the dendrites or cell body of the next, across which a nerve impulse is transmitted. The two neurons do not touch; they are separated by a minute gap, the synaptic cleft.

In the CEREBRUM the CYTONS lie on the OUTSIDE, forming the outer GREY matter, while the AXONS lie INSIDE, forming the inner WHITE matter.

Two separate questions in one part, so answer both distinctly.

FOR THE SYNAPSE, the essential point is that the neurons DO NOT TOUCH. The impulse travels electrically along a neuron but cannot jump the gap, so at the synapse it is converted into a CHEMICAL signal carried by a neurotransmitter (ACETYLCHOLINE) and turned back into an electrical impulse in the next neuron. Because transmission across the gap works one way only, the synapse ensures impulses travel in a single direction.

FOR THE CEREBRUM: grey matter is made of CYTONS, white matter of AXONS (white because of their myelin sheaths). In the BRAIN grey is OUTSIDE; in the SPINAL CORD the arrangement is REVERSED.

WHY the cerebrum is built this way: putting the cell bodies on the surface allows it to be deeply folded, which greatly increases the area available for them — and more cell bodies means greater capacity for thought and memory.