what it´s the brain?

The brain is the center of the nervous system in all in all types of vertebras and almost all invertebrate animals; sponges, jellyfish, adult sea squirts and starfish such as these invertebrates do not have one, even if  neural tissue is present doesn’t mean that will have, this the neural tissue is located in the head, almost always it is really close to the primary sensory organs such sense as the vision, the hearing, the balance, the taste, and for last the smell.

In a typically human body the is the cerebral cortex that is the largest part and this part is estimated that will contain 15-33 billion neurons all these neurons connected to other thousands of neurons in the brain all each connected. All these neurons communicate one to each other’s by long protoplasmic fibers called axons by witch these carry signals pulses and this pulses are called action potential and this action potential arrive to different types of the brain .

In an evolutionary – biological point of view the function of the brain is to take control over others organs in the body , and in the rest of the body the brain act as generating patterns with all muscles activities or by secretion on chemicals called hormones. And this control let rapid and coordinated changes of  the environment, some just basic types of responsive reaction such as the reflect mediate the spinal cord .