Chapter two vocab

2. The bushy, branching extensions of a neuron that receive messages and conduct impulses toward the cell body.
5. A neurotransmitter that, among its functions, triggers muscle contraction.
7. The level of stimulation required to trigger a neural impulse.
9. Chemical messengers that traverse the synaptic gaps between neurons. When released by the sending neuron, they travel across the synapse and bind to receptor sites on the receiving neuron, thereby influencing whether that neuron will generate a neural impulse.
13. The body's speedy, electrochemical communication system, consisting of all the nerve cells of the peripheral and central nervous systems.
14. The extension of a neuron, ending in branching terminal fibers, through which messages pass to other neurons or to muscles or glands.

1. "morphine within" -- natural, opiatelike neurotransmitters linked to pain control and to pleasure.
3. A neural impulse a brief electrical charge that travels down an axon. Generated by the movement of positively charged atoms in a nd out of channels in the axon's membrane.
4. Tissue destruction.
6. A technique that uses magnetic fields and radio waves to produce computer-generated images that distinguish among different types of soft tissue; allows us to see structures within the brain.
8. The junction between the axon tip of the sending neuron and dendrite or cell body of the the receiving neuron. The tiny gap at this junction is called the synaptic gap or cleft.
10. A simple, automatic, inborn response to a sensory stimulus, such as the knee-jerk response.
11. A nerve cell; the basic building block of the nervous system
12. A layer of fatty tissue segmentally encasing the fivers of many neurons; enables vastly greater transmission speed of neural impulses as the impulse hops from one node to the next.
13. 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.