2. neuron: a nerve cell; the basic building block of the nervous system nerve cell tree ipod
3. dendrite: the brushy, branching extensions of a neuron that receive messages and conduct impulses toward the cell body tree receive
4. axon: the extensions of the neuron, ending in branching terminal fibers, through which messages pass to other neurons or to muscles or glands tree send
5. myelin: a layer of fatty tissue segmentally encasing the fibers of many neurons; enables vastly greater transmission speed of neural impulses as the impulse hops from one node to the next cord insulate speed_up
6. action potential: a neural impulse; a brief electrical charge that travels down an axon. the action potential is generated by the movement of positively charged atoms in and out of channels in the axon's membrane energy pulse electricity
7. threshold :the level of stimulation required to trigger a neural impulse all or nothing guns
8. synapse: the junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron. the tiny gap at this junction is called the synaptic gap or cleft. knee-cap kiss
9. neurotransmitters: chemical messengers that traverse the synaptic gaps between neurons. when released by the sending neuron, neurotransmitters travel across the synapse and bind to receptor sites on the receiving neuron, thereby influencing whether the neuron will generate a neural impulse endorphins acetylchlorine
10. acetylchlorine: a neurotransmitter that, among its functions, triggers muscle contraction muscles contraction
11. endorphins: "morphine within" -natural, opiatelike neurotransmitters linked to pain and control and to pleasure morphine pleasure
12. nervous system: the body's speedy, electrochemical communication system, consisting of all the nerve cells of the peripheral and central nervous system information system nerves
13. central nervous system: the brain and spinal cord highway understanding
14. peripheral nervous system: the sensory and motor neurons that connect the central nervous system to the rest of the body links connect
15. nerves: neural "cables" containing many axons. these bundled axons, which are part of the peripheral nervous system, connect the central nervous system with muscles, glands, and sense organs. cables connect
16. sensory neurons: neurons that carry incoming information from the sense receptors to the central nervous system send carry ingoing
17. interneurons: central nervous system neurons that internally communicate and intervene between the sensory inputs and motor outputs communicate process
18. motor neurons: neurons that carry outgoing information from the central nervous system to the muscles and glands outgoing carry instructions
19. somatic nervous system: the division of the peripheral nervous system that controls the body's skeletal muscles skeletal nervous system movement
20. autonomic nervous system: the part of the peripheral nervous system that controls the glands and the muscles of the internal organs. automatic heartbeat pupil dilation
21. sympathetic nervous system: the division of the autonomic nervous system that arouses the body, mobilizing its energy in stressful situations stress responses freak-out
22. parasympathetic nervous system: the division of the autonomic nervous system that calms the body, conserving its energy calm-down pupil contraction
23. reflex: response to a sensory stimulus, such as the knee-jerk response automatic inborn simple response
24. neural networks: interconnected neural cells. with experience, networks can learn, as feedback strengthens or inhibits connections that produce certain results use it or lose it learning feedback
25. lesion: tissue destruction defective cells tumor
26. electroencephalogram: an