6.5 Neurons and Synapses

3. the long thread-like extension of a nerve cell that conducts nerve impulses from the cell body.
5. an electronic instrument used to observe and measure changing electrical signals.
7. the junction between two nerve cells, consisting of a minute gap across which impulses pass by neurotransmitters.
9. the critical level to which the membrane potential must be depolarized in order to initiate an action potential.
11. the change in membrane potential that returns the membrane potential to a negative value after the depolarization phase of an action potential.
12. a neuron from which an electrical impulse is transmitted across a synaptic cleft to a postsynaptic neuron by the release of a chemical neurotransmitter.
13. a localized change in electrical potential, from about -70 mV to +30 mV and back again, that occurs across a nerve fibre during transmission of a nerve impulse.
15. a molecule released by neurons at the neuromuscular junction that causes muscle contraction.
16. a specialized, impulse-conducting cell that is the functional unit of the nervous system, consisting of the cell body and its processes, the axon, and dendrites.

1. a junction between two cells that employs acetylcholine as its transmitter substance.
2. the delay after repolarization where the resting potential is restored.
4. a substance that transmits nerve impulses across a synapse.
6. the propagation of action potentials along myelinated axons from one node of Ranvier to the next node, increasing the conduction velocity of action potentials.
8. a positive-going change in the membrane potential of neurons making it more positive, or less negative. It may result in an action potential.
10. the potential difference between the two sides of the membrane of a nerve cell when the cell is not conducting an impulse.
14. the process of development or formation of a myelin sheath around a nerve fibre.