Terms : Hide Images
| 1059564726 | neuron | specialized cell in the nervous system that accumulates and transmits information | |
| 1059564727 | dendrites | the branched part of a neuron that receives impulses and conducts them toward the cell body | |
| 1059564728 | cell body | the portion of the neuron containing the metabolic machinery that keeps the cell alive and functional (nucleus) | |
| 1059564729 | axon | the part of a neuron that transmits impulses to glands, muscles, or other neurons | |
| 1059564730 | efferent neurons | nerves that carry messages outward from the central nervous system | |
| 1059564731 | afferent neurons | nerves that carry messages inward toward the central nervous system | |
| 1059564732 | interneurons | neurons that are neither efferent nor afferent, but instead carry information from one neuron to another | |
| 1069727172 | glia | a type of cell in the nervous system long believed to provide a "support" function for neurons; recent research indicates that glia provide many other functions as well | |
| 1069727173 | myelin | a fatty substance that makes up some types of glial cells; these cells wrap around the axon of some neurons, providing an insulating "myelin sheath" around these neurons [myelinated axons = "white matter"] | |
| 1069727174 | action potential | a brief change in the electrical charge of a neuronal membrane; the physical basis of the signal that travels the length of the neuron (fundamental information carrier of the nervous system) | |
| 1069727175 | resting potential | the voltage difference between the inside and the outside of a neuronal membrane when the neuron is not firing (~-70 millivolts) | |
| 1069727176 | excitation threshold | the voltage difference between a neuron's interior and exterior that, if exceeded, causes the neuron to fire (~-55 millivolts). In this millisecond-long occurrence, the voltage difference collapses and reverses, so that the difference is closer to +40 | |
| 1069727177 | refractory period | the time after an action potential during which a neuron's cell membrane is unprepared for the next action potential (only a few milliseconds) | |
| 1069727178 | depolarize | in the nervous system, to lose the charge that normally exists across neuronal membrane. happens in a domino-like sequence along the axon | |
| 1069727179 | propagation | the spread of the action potential down an axon, caused by successive changes (domino-like) in electrical charge along the length of the axon's membrane | |
| 1069727180 | all-or-none law | the law that all action potentials have the same strength and speed regardless f the triggering stimulus | |
| 1070901457 | synapse | the small gap between two adjacent neurons, consisting of the presynaptic and postsynaptic neurons' membranes and the space between them | |
| 1070901458 | neurotransmitters | chemicals released by one neuron (usually the presynaptic neuron), which trigger a response in another neuron (usually the postsynaptic neuron); the chief means of communication among neurons | |
| 1070901459 | synaptic reuptake | the presynaptic neuron's process of reabsorbing its own neurotransmitters after signaling so that they can be released again the next time the neuron fires (prevents them from still exerting effects even after neuron fires) |
