Brain

The brain is a pinkish-grey, wrinkled organ that fills the skull — looking, for all the world, like a huge walnut. It is hard to believe, from its appearance, that this ugly lump of jelly contains the mechanisms of thought, perception, will, and consciousness, that it is the seat of our personality. Its 100,000 million nerve cells, each with an average of 100,00 connections from other neurons, makes the human brain the most complicated and least understood object in the known universe. The vertebrate brain is the large anterior portion of the central nervous system . The "cranial vault" of the skull encases the brain in most vertebrates. In invertebrates, the enlarged and specialized anterior ganglion of the central nervous system is often referred to as a brain, although not all scientists regard it as a true brain.

Psychiatric disorders

The term psychiatric disorder means a mental disorder or illness that interferes with the way a person behaves, interacts with others, and functions in daily life. Psychiatric disorders are also sometimes known as mental health disorders or mental health illnesses. Symptoms of psychiatric disorders rarely occur suddenly. In most cases, symptoms develop over time. Close friends and family members of people with psychiatric disorders may realize that something is wrong or not quite right before the disorder itself is recognized.