Nervous system

Abstract

The human nervous system weighs “only” about 4.5 pounds, which accounts for approximately 3% of the entire body. It is a small and complex body system that consists of an intricate network of nervous cells (or neurons) and even more glial cells. How many nervous cells does a human have? Billions, is the simple answer. However, from a medical point of view, the more important questions are: how does the nervous system work, and what does its structure look like?