Psychology Section 1 “The Nervous System” The human nervous system is involved in thinking, dreaming, feeling, moving and much more. It is working when we are active or still, awake or asleep. The nervous system regulates our internal functions and how we react to the external world. The nervous system has 2 main parts: The Central Nervous System, which consists of: The brain The Spinal Chord The Peripheral Nervous System The Peripheral Nervous System Is made up of the nerve cells that send messages between the central nervous system and all the parts of the body. Neurons Neurons are nerve cells; they run through our entire body and communicate with each other. Neurons send and receive messages from other structures. Each of us has more than 100 billion neurons, most of which are found in the brain. Components of a Neuron Neurons are somewhat like trees in structure. Parts of neurons resemble the branches, trunk and roots of a tree. Every neuron consists of a cell body, dendrites, and an axon. Cell body: The cell body produces energy that fuels the activity of the cell. Dendrites: They receive information from other neurons and pass messages through the cell body. They carry information to the cell body. Axon: Axons carry information away; a neuron has many dendrites but usually only one axon. Axons vary in length, some are just a tiny fraction of an inch and others stretch to several feet. Myelin: A white fatty substance that insulates and protects the axon. It also speeds up the transmission of the message. Axon Terminals: Small fibers that branch out. Section Review 1. Name the two parts of the nervous system. 2. What are neurons? 3. Name and describe the parts of a neuron. 4. Homework: Draw color and label 5 different kinds of neurons, turn them in next class Friday Dec. 7, in a folder with your name.