The human brain is the most complex part of our body. All the movements of human body are initiated by human brain. The human behaviour is controlled by brain. The human senses are interpreted by brain.
The human brain consists of three basic parts, having different properties: hind-brain, mid-brain, fore-brain. The fore-brain is the largest and the most developed part of the human brain. The fore-brain consists of two basic structures: cerebrum, inner brain. The cerebrum is responsible for memories and all intellectual activities. The cerebrum is divided into two hemispheres, each having different properties. The left hemisphere is responsible for words forming and the right hemisphere is responsible for abstract reasoning. Each hemisphere is responsible for the opposite part of the body. Therefore, if the left hemisphere is damaged, then the right part of the body is affected.
The hind-brain consists of cerebellum, the upper part of spinal cord, the brain stem. The movements of the body are controlled by hind-brain. The mid-brain controls reflex actions and voluntary movements.
The layer of tissue that covers the cerebrum and cerebellum is called cerebral cortex, or gray matter. The amount of information that can be processed depends on the quantity of the gray matter. Therefore, the more larger the surface area of gray matter is, the more information can be processed.
The inner brain is responsible for reflex movements, emotional states and responses to these emotional states.
The basic functional unit of the brain is the cell called neuron. The results of signals passing through neurons are feelings, sensations, movements, memories, thoughts. The neuron consists of three units: neuron body, dendrites, axon. The cell body contains the nucleus. Dendrites receive messages from other nerve cells. The signals pass through dendrites and axon to another neuron or other type of cell in other organ from human body.
The key excitatory or inhibitory neurotransmitters are acetylcholine, GABA, serotonin and dopamine.