A typical nerve consists three basic parts. The body or soma is bounded by a thin and very fine membrane that is comprised chiefly of lipids. The interior is filled with liquid and contains a nucleus, organelles such as mitochondria, and other specialized protein structures. Extending from the body is an elongated appendage that conducts messages away from the cell body termed an axon. The soma also projects dendrites, which are short branching terminals that receive information from other nerves. Neurons are designed to quickly transmit information by employing electrical as well as chemical signals. Chemical signaling alone, such as used by plants, is much too slow for life forms that move about freely and are not anchored to the earth. Additionally, to further enhance speed, many of the transmitting appendages or axons are wrapped in a sheath of myelin that can insulate electrical signals. The nerve also coordinates with the endocrine system and receives chemical messengers such as hormones by forming specialized protein structures referred to as receptor sites.