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| 9752175177 | neuron | A nerve cell; the fundamental unit of the nervous system, having structure and properties that allow it to conduct signals by taking advantage of the electrical charge across its plasma membrane. |  | 0 |
| 9752175178 | brain | Organ of the central nervous system where information is processed and integrated. | 1 | |
| 9752175179 | ganglion | A cluster (functional group) of nerve cell bodies in a centralized nervous system. |  | 2 |
| 9752175180 | cell body | The part of a neuron that houses the nucleus and most other organelles. |  | 3 |
| 9752175181 | dendrite | One of usually numerous, short, highly branched extensions of a neuron that receive signals from other neurons. |  | 4 |
| 9752175182 | axon | A typically long extension, or process, of a neuron that carries nerve impulses away from the cell body toward target cells. |  | 5 |
| 9752175183 | axon hillock | The cone-shaped base of an axon, where signals that travel down the axon are generated. |  | 6 |
| 9752175184 | synapse | The junction where a neuron communicates with another cell across a narrow gap via a neurotransmitter or an electrical coupling. |  | 7 |
| 9752175185 | synaptic terminal | The part of each axon branch that forms a synapse. |  | 8 |
| 9752175186 | neurotransmitter | A molecule that is released from the synaptic terminal of a neuron at a chemical synapse, diffuses across the synaptic cleft, and binds to the postsynaptic cell, triggering a response. | 9 | |
| 9752175187 | presynaptic neuron | The neuron that transmits a signal to another cell. |  | 10 |
| 9752175188 | postsynaptic cell | The neuron, muscle, or gland cell that receives a signal from a neuron. |  | 11 |
| 9752175189 | glia | Cells of the nervous system that support, regulate, and augment the functions of neurons. |  | 12 |
| 9752175190 | sensory neuron | A nerve cell that receives information from the internal or external environment and transmits signals to the central nervous system. | 13 | |
| 9752175191 | interneuron | An association neuron; a nerve cell within the central nervous system that forms synapses with sensory and/or motor neurons and integrates sensory input and motor output. |  | 14 |
| 9752175192 | motor neuron | A nerve cell that transmits signals from the brain or spinal cord to muscles or glands. | 15 | |
| 9752175193 | central nervous system | The portion of the nervous system where signal integration occurs, in vertebrate animals, the brain and spinal cord. | 16 | |
| 9752175194 | peripheral nervous system | The sensory and motor neurons that connect to the central nervous system. | 17 | |
| 9752175195 | nerve | A fiber composed primarily of the bundled axons of neurons. | 18 | |
| 9752175196 | membrane potential | The difference in electrical charge (voltage) across a cell's plasma membrane due to the differential distribution of ions. | 19 | |
| 9752175197 | resting potential | The membrane potential characteristic of a nonconducting excitable cell, with the inside of the cell more negative than the outside. | 20 | |
| 9752175198 | sodium-potassium pump | A transport protein in the plasma membrane of animal cells that actively transports sodium out of the cell and potassium into the cell. |  | 21 |
| 9752175199 | ion channel | A transmembrane protein channel that allows a specific ion to diffuse across the membrane down its concentration or electrochemical gradient. |  | 22 |
| 9752175200 | selective permeability | Property of ion channels that allows only certain ions to pass through to the other side of the membrane. |  | 23 |
| 9752175201 | equilibrium potential | The magnitude of a cell's membrane voltage at equilibrium, calculated using the Nernst equation. | 24 | |
| 9752175202 | gated ion channel | A gated channel for a specific ion. The opening or closing of such channels may alter a cell's membrane potential. | 25 | |
| 9752175203 | hyperpolarization | A change in a cell's membrane potential such that the inside of the membrane becomes more negative relative to the outside. Reduces the chance that a neuron will transmit a nerve impulse. | 26 | |
| 9752175204 | depolarization | A change in a cell's membrane potential such that the inside of the membrane is made less negative relative to the outside. | 27 | |
| 9752175205 | graded potential | In a neuron, a shift in the membrane potential that has an amplitude proportional to signal strength and that decays as it spreads. | 28 | |
| 9752175206 | action potential | An electrical signal that propagates (travels) along the membrane of a neuron or other excitable cell as a nongraded (all-or-none) depolarization. | 29 | |
| 9752175207 | voltage-gated ion channel | A specialized ion channel that opens or closes in response to changes in membrane potential. | 30 | |
| 9752175208 | threshold | The potential that an excitable cell membrane must reach for an action potential to be initiated. | 31 | |
| 9752175209 | refractory period | The short time immediately after an action potential in which the neuron cannot respond to another stimulus, owing to the inactivation of voltage-gated sodium channels. | 32 | |
| 9752175210 | myelin sheath | Wrapped around the axon of a neuron, an insulating coat of cell membranes from Schwann cells or oligodendrocytes. It is interrupted by nodes of Ranvier, where action potentials are generated. |  | 33 |
| 9752175211 | oligodendrocyte | A type of glial cell that forms insulating myelin sheaths around the axons of neurons in the central nervous system. |  | 34 |
| 9752175212 | Schwann cell | A type of glial cell that forms insulating myelin sheaths around the axons of neurons in the peripheral nervous system. | 35 | |
| 9752175213 | node of Ranvier | Gap in the myelin sheath of certain axons where an action potential may be generated. |  | 36 |
| 9752175214 | saltatory conduction | Rapid transmission of a nerve impulse along an axon, resulting from the action potential jumping from one node of Ranvier to another, skipping the myelin-sheathed regions of membrane. | 37 | |
| 9752175215 | synaptic vesicle | Membrane-enclosed compartment at the terminal of a presynaptic neuron that contains neurotransmitter. |  | 38 |
| 9752175216 | synaptic cleft | The gap that separates the presynaptic neuron from the postsynaptic cell. |  | 39 |
| 9752175217 | ligand-gated ion channel | A transmembrane protein containing a pore that opens or closes as it changes shape in response to a signaling molecule (ligand), allowing or blocking the flow of specific ions. | 40 | |
| 9752175218 | ionotropic receptor | A ligand-gated ion channel.. | 41 | |
| 9752175219 | postsynaptic potential | A graded potential in a postsynaptic cell. | 42 | |
| 9752175220 | excitatory postsynaptic potential | An electrical change (depolarization) in the membrane of a postsynaptic cell caused by the binding of an excitatory neurotransmitter from a presynaptic cell to a postsynaptic receptor; makes it more likely for a postsynaptic cell to generate an action potential. | 43 | |
| 9752175221 | inhibitory postsynaptic potential | An electrical change (usually hyperpolarization) in the membrane of a postsynaptic neuron caused by the binding of an inhibitory neurotransmitter from a presynaptic cell to a postsynaptic receptor; makes it more difficult for a postsynaptic neuron to generate an action potential. | 44 | |
| 9752175222 | temporal summation | A phenomenon of neural integration in which the membrane potential of the postsynaptic cell in a chemical synapse is determined by the combined effect of EPSPs or IPSPs produced in rapid succession. | 45 | |
| 9752175223 | spatial summation | A phenomenon of neural integration in which the membrane potential of the postsynaptic cell is determined by the combined effect of EPSPs or IPSPs produced nearly simultaneously by different synapses. | 46 | |
| 9752175224 | metabotropic receptor | Binds a neurotransmitter and activates a signal transduction pathway that opens or closes an ion channel after one or more metabolic steps. | 47 | |
| 9752175225 | acetylcholine | One of the most common neurotransmitters; functions by binding to receptors and altering the permeability of the postsynaptic membrane to specific ions, either depolarizing or hyperpolarizing the membrane. |  | 48 |
| 9752175226 | neuromuscular junction | The site where a motor neuron forms a synapse with a skeletal muscle cell. | 49 | |
| 9752175227 | glutamate | An amino acid that functions as a neurotransmitter in the central nervous system and has a role in long term memory. |  | 50 |
| 9752175228 | GABA | An amino acid that functions as a neurotransmitter in the central nervous system of vertebrates where it is found at most inhibitory synapses in the brain. |  | 51 |
| 9752175229 | biogenic amines | A neurotransmitter derived from an amino acid. |  | 52 |
| 9752175230 | norepinephrine | A catecholamine that is chemically and functionally similar to epinephrine and that acts as a hormone or neurotransmitter; also known as noradrenaline. |  | 53 |
| 9752175231 | dopamine | A neurotransmitter that is a catecholamine, like epinephrine and norepinephrine. |  | 54 |
| 9752175232 | serotonin | A neurotransmitter, synthesized from the amino acid tryptophan, that functions in the central nervous system. |  | 55 |
| 9752175233 | neuropeptide | A relatively short chain of amino acids that serves as a neurotransmitter. | 56 | |
| 9752175234 | endorphin | Any of several hormones produced in the brain and anterior pituitary that inhibit pain perception. | 57 |
