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Definition
| relatively stable conditions of the internal environment that result from compensating regulatory responses |
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Term
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Definition
| a system in which a particular variable is not changing but energy must be continuously added to maintain this constant |
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Term
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Definition
| a system in which an increase or decrease in a variable being regulated brings about responses that tend to move the variable in the direction opposite to the direction of a change |
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Term
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Definition
| a system in which an initial disturbance sets off a train of events that increase the disturbance even further |
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Definition
| regulation that anticipates changes in a regulated variable and improves the speed of the body's homeostatic responses and minimizes fluctuations |
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Term
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Definition
| a detectable change in the internal or external environment |
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Definition
| a detector of an environmental change |
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Definition
| pathway traveled by the signal between the receptor and the integrating center |
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Term
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Definition
| central point which receives signals from many receptors (through afferent pathways) |
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Term
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Definition
| a device whose change in activity constitutes the overall response of the system |
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Term
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Definition
| pathway traveled by the signal between the integrating center and the effector |
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Term
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Definition
| chemical messengers involved in local communication between cells |
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Term
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Definition
| chemical messengers that act upon the cell that secreted them |
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Term
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Definition
| ability of a receptor to bind to only one type or a limited number of structurally related types of chemical messengers |
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Term
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Definition
| the degree to which receptors are occupied by a messenger |
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Term
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Definition
| strength with which a chemical binds to its receptor |
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Term
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Definition
| ability of different molecules with similar structures to combine with the same receptor |
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Term
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Definition
| a molecule that competes for a receptor with a chemical messenger normally present in the body; binds without triggering a response |
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Term
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Definition
| a chemical messenger that binds to a receptor and triggers a cell's response |
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Term
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Definition
| a decrease in the total number of target-cell receptors for a given messenger in response to chronic high extracellular concentration of the messenger |
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Term
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Definition
| an increase in the total number of target-cell receptors for a given messenger in response to a chronic low extracellular concentration of the messenger |
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Term
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Definition
| basic unit of nervous tissue; serve as integrators |
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Term
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Definition
| chemical messengers that pass from neuron to targets |
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Term
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Definition
| highly branched outgrowths from cell body which receive information and input |
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Term
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Definition
| a single long process that extends from the cell body to its target cells |
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Term
| axon hillock (initial segment) |
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Definition
| portion of axon closest to the cell body where the axon is joined |
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Term
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Definition
| bulging areas along axons where some neurons release their chemical messengers |
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Term
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Definition
| convey information from tissues and organs into the central nervous system |
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Term
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Definition
| convey information from the central nervous system to tissues and organs |
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Term
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Definition
| specialized junction between two neurons where one neuron alters the activity of another |
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Term
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Definition
| non-neuron cells in the central nervous system; metabolically and physically support neurons |
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Term
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Definition
| regulate composition of extracellular fluid in the central nervous system by removing K+ ions and neurotransmitters around synapses |
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Term
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Definition
| serve as immune cells of the central nervous system |
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Term
| resting membrane potential |
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Definition
| a potential difference across the plasma membrane of cells and the extracellular fluid |
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Term
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Definition
| occurs when the potential is less negative than the resting level |
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Term
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Definition
| occurs when a depolarized membrane potential returns toward the resting level |
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Term
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Definition
| a potential change of variable amplitude and duration that is conducted decrementally; no threshold or refractory period |
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Term
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Definition
| a brief all-or-none depolarization of the membrane; has a threshold and refractory period and is conducted without decrement |
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Term
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Definition
| a graded potential change produced in the postsynaptic neuron in response to release of a neurotransmitter by a presynaptic terminal; may be depolarizing or hyperpolarizing |
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Term
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Definition
| a graded potential produced at the peripheral endings of afferent neurons in response to a stimulus |
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Term
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Definition
| a spontaneously occurring graded potential change that occurs in certain specialized cells |
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Term
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Definition
| weak depolarization in which an action potential does not occur |
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Term
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Definition
| using nodes of Ranvier, action potentials jump from one node to the next as they propagate along a myelinated fiber |
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Term
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Definition
| extracellular space between the axon of a presynaptic cell and the postsynaptic cell |
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Term
| excitatory post synaptic potential (EPSP) |
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Definition
| a graded potential that spreads decrementally away from the synapse by local current and brings the membrane potential of the post synaptic neuron closer to threshold |
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Term
| inhibitory post synaptic potential (IPSP) |
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Definition
| uses various mechanisms (such as graded positive potentials) to move the membrane potential away from depolarization |
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Term
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Definition
| multiple stimuli, one after another, that increase or decrease each other |
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Term
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Definition
| multiple stimuli from multiple sources that increase or decrease each other |
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Term
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Definition
| fibers that release acetylcholine (ACh) |
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Term
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Definition
| dopamine, norepinephrine, and epinephrine |
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Term
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Definition
| releasing epinephrine or norepinephrine |
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Term
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Definition
| molecule that is generally excitatory for muscle control pathways and inhibitory for sensing pathways |
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Term
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Definition
| widely used molecule in body for excitatory responses |
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Term
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Definition
| widely used molecule in body for inhibitory responses |
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Term
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Definition
| groups of neuron cell bodies in the PNS |
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Term
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Definition
| groups of neuron cell bodies in the CNS |
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