The nervous system is a complex communication network in which signals are received, integrated and transmitted via neurons.

The endocrine system is another communication system within the body whereby hormones are secreted into the blood stream via glands.

The nervous system is made up of living tissue, composed mainly of cells. There are two types of cells, glia and the neurons. The glia make up the support system and the neurons permit communication through out the nervous system.

The nervous system is divided into the central nervous system, which is composed of the brain and the spinal cord, and the peripheral nervous system, which contains all of the nerves exterior to the brain and the spinal cord. The brain is divided into three categories the forebrain, midbrain and the hindbrain.

The peripheral nervous system is further divided into the somatic nervous system, which controls voluntary reflexes and the autonomic nervous system, which controls involuntary muscles of the internal organs and the glands. E.g. The heart. The autonomic ner

Due to the fact that neurons communicate through electrical impulses, the speed of transmission of a message is very fast (usually in milliseconds). The endocrine system has a much slower speed of transmission of messages (usually minutes) because hormones rely on the circulatory system to reach target cells.

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