The Nervous System
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Created by:
ranaranarana on September 20, 2011
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14 terms
Terms | Definitions |
|---|---|
 central nervous system | consists of the brain and the spinal cord |
| peripheral nervous system | is made up of nerve cells that send messages between the CNS and other parts of the body |
| nervous system | 2 parts: central and peripheral |
| neurons | are nerve cells that run through our entire bodies and communicate with each other; each of us has 100 billion of these, most of which are in the brain |
| cell body | produces energy that fuels the neuron's activity |
| dendrites | thin fibers branching out from the cell body; they receive info from other neurons and pass the message through the cell body; carries info to the cell body |
| axon | transmits messages away from the cell body; a neuron usually has only one axon; they vary greatly in length. |
| myelin | many axons are covered with this white fatty substance that insulates and protects the axon; this casing also helps to speed up the transmission of the messages sent by neurons |
| axon terminals | at the end of the axon, these small fibers branch out |
| synapse | is a junction between the axon terminals of one neuron and the dendrites of another; messages only travel in one direction |
| neurotransmitters | neurons send messages across synapses through the release of this; these are the chemicals that are stored in sacs in the axon terminals |
| spinal cord | is a column of nerves about as thick as a thumb that extends from the brain down the back. It's protected by the bones of the spine and transmits messages between the brain and the muscles and glans in the body |
| somatic nervous system | transmits sensory messages to the central nervous system. Its function is to carry messages from voluntary muscles and sense organs |
| autonomic nervous system | regulates the body's vital functions, such as heartbeat, breathing, digestion, and blood pressure; we generally do not think of these activities |
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