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Raksha Goswami
Chapter 19
| Term | Definition |
|---|---|
| Resting membrane potential (RMP) | Membrane voltage when the neuron is not excited and not conducting an impulse, Polarized |
| Local potential | Temporary fluctuation in a local region of the membrane in response to a sensory or nerve stimulus; may be an upward or downward fluctuation in voltage; loses amplitude as it spreads along membrane |
| Threshold potential | Minimum local depolarization needed to trigger voltage-gated channels that produce the action potential |
| Saltatory conduction | the insulating nature of the myelin sheath prevents ion movement everywhere but at the nodes of Ranvier. The action potential at one node triggers current flow (arrows) across the myelin sheath to the next node—producing an action potential there. The act |
| Electrical Synapse | Electrical synapses occur where two cells are joined end to end by gap junctions. Because the plasma membranes and cytoplasm are functionally continuous in this type of junction, an action potential can simply continue |
| Chemical Synapese | Three structures make up a chemical synapse: 1. A synaptic knob 2. A synaptic cleft 3. The plasma membrane of a postsynaptic neuron A synaptic knob is a tiny bulge at the end of a terminal branch of a presynaptic neuron’s axon . Each synaptic knob, or s |
| Amine neurotransmitters | are synthesized from amino acid mole-cules, such as tyrosine, tryptophan, or histidine. Amines include the neurotransmitters of the monoamine subclass: serotonin and hista-mine. Monoamines have a single amine (NH2) group, as their name implies. |
| Acetylcholine | The neurotransmitter acetylcholine (ACh) is in a class of its own because it has a chemical structure unique among neurotransmit-ters. It is synthesized in neurons by combining an acetate (acetyl coenzyme A) with choline (sometimes listed as a B vitamin) |
| Neurotransmitters | the means by which neurons talk to one an-other. At billions, or more likely, trillions, of synapses throughout the body, presynaptic neurons release neurotransmitters that act to facili-tate, stimulate, or inhibit postsynaptic neurons and effector cells |
| depolarization | The opening of stimulus-gated Na⫹channels in response to a stimulus permits more Nato enter the cell. As the excess of positive ions outside the plasma membrane decreases, the magnitude of the membrane potential is reduced. Such movement of the membrane |
| hyperpolarization. | Movement of the membrane potential away from zero (thus be-low the usual RMP) . |
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Raksha Goswami
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