Neurons

• Neurons carry electrical signals and messages called nerve impulses from one part of the body to another at very high speeds. The nerve impulses only travel in one direction.
• A neuron contains have five main parts: cell body, dendrites, an axon, an axon terminal and a myelin sheath.
• Cell body: contains nucleus (control centre of neuron) and sends information from dendrites to axon.
• Dendrites: branches out from cell body and receive information from other neurons. (More dendrites = more information)
• Axon: sends nerve impulses away from cell body and allows signals to be transferred over long distances.
• Axon terminal: passes the nerve impulse on
• Myelin Sheath: insulates the axon so that it can transmit faster.
• Motor neurons carry messages away from CNS. They carry messages from brain and spinal cord (CNS) to the muscles and glands.
• Schwann cell: A type of glial cell that forms myelin sheaths around axons.
• Node of ranvier: allow for ions to diffuse in and out of the neuron, propagating the electrical signal down the axon.
• Sensory neurons carry messages towards the central nervous system. All of the body's receptors are sensory neurons. A sensory neuron's cell body hangs off its axon and does not have any dendrites attached to it.
• Relay neurons link sensory neurons to motor neurons. They can also connect to other relay neurons. They only exist in the CNS. Looks like a motor neuron; however, they usually do not need a myelin sheath and are therefore shorter.