Neural or brain tissue is specialized for communication through the transmission of electrical signals. The majority (approximately 98%) of neural tissue is found within the brain and the spinal cord. It is composed of two basic classes of cells: nerve cells (or neurons), which transmit communication signals, and glial cells, which act to support both the structure and function of neurons. The basic functional unit of the brain is the neuron. Its functional role is to send and receive the electrical impulses that communicate messages about sensory, motor, and cognitive events throughout the brain. The average brain contains roughly 100 billion neurons. Although there are upwards of 1,000 different types of neurons, they all have the same basic structure and function. Each neuron has a soma, or cell body, that performs all the basic metabolic functions required to keep the cell alive and functioning. The brain is largest and complex organs in the human body. It is made up of more than billions of nerves that communicate in trillions of connections with body systems for organized function. The human brain is larger when compared to the other mammals. The human brain is made up of cerebral cortex, brain stem, cerebrum and cerebellum. The brain also divided into four lobes frontal, parietal, temporal and occipital lobes.