| postsynaptic membrane | That part of the plasma membrane of a neuron or muscle fibre with which an axon terminal forms a synaptic junction; in many instances, at least part of such a small postsynaptic membrane patch shows characteristic morphological modifications such as greater thickness and higher electron-density, believed to correspond to the transmitter-sensitive receptor site of such synapses. (05 Mar 2000) |
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| postsynaptic | Pertaining to the area on the distal side of a synaptic cleft. (05 Mar 2000) |
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| postsynaptic cell | In a chemical synapse, the cell that receives a signal (binds neurotransmitter) from the presynaptic cell and responds with depolarisation In an electrical synapse, the postsynaptic cell would just be downstream, but since many electrical synapses are rectifying, one of the two cells involved will always be postsynaptic. (18 Nov 1997) |
| postsynaptic potential | In a synapse, a change in the resting potential of a postsynaptic cell following stimulation of the presynaptic cell. For example: in a cholinergic synapse, the release of acetylcholine from the presynaptic cell causes channels to open in the postsynaptic cell. Each channel opening causes a small depolarisation, known as a miniature end plate potential (mepp), these sum to produce an excitatory postsynaptic potential. (18 Nov 1997) |
| inhibitory postsynaptic potential | The change in potential produced in the membrane of the next neuron when an impulse which has an inhibitory influence arrives at the synapse; it is a local change in the direction of hyperpolarization; the frequency of discharge of a given neuron is determined by the extent to which impulses that lead to excitatory postsynaptic potential's predominate over those that cause inhibitory postsynaptic potential's. (05 Mar 2000) |
| excitatory postsynaptic potential | The change in potential which is produced in the membrane of the next neuron when an impulse which has an excitatory influence arrives at the synapse; it is a local change in the direction of depolarisation; summation of these potential's can lead to discharge of an impulse by the neuron. (05 Mar 2000) |
| excitatory postsynaptic potentials | The change in potential produced in the membrane of the next neuron when an impulse which has an excitatory influence arrives at the synapse; it is a local change in the direction of depolarisation; summation of these potentials can lead to discharge of an impulse by the neuron. (12 Dec 1998) |
| adamantine membrane | The primary enamel cuticle, consisting of two extremely thin layers (the inner one clear and structureless, the outer one cellular), covering the entire crown of newly erupted teeth and subsequently abraded by mastication; it is evident microscopically as an amorphous material between the attachment epithelium and the tooth. Synonym: cuticula dentis, adamantine membrane, dental cuticle, membrana adamantina, Nasmyth's cuticle, Nasmyth's membrane, skin of teeth. (05 Mar 2000) |
| allantoid membrane | An embryonic diverticulum of the hindgut of reptiles, birds, and mammals; in man its blood vessels give rise to those of the umbilical cord. (12 Dec 1998) |
| alveolocapillary membrane | The pulmonary diffusion barrier. (05 Mar 2000) |
| alveolodental membrane | <anatomy> Fibrous connective tissue surrounding the root of a tooth that separates it from and attaches it to the alveolar bone. (12 Dec 1998) |
| anal membrane | The dorsal portion of the embryonic cloacal membrane after its division by the urorectal septum. Anterior atlanto-occipital membrane, the fibrous layer that extends from the anterior arch of the atlas to the anterior margin of the foramen magnum. Synonym: membrana atlanto-occipitalis anterior. (05 Mar 2000) |
| anisotropic membrane | This type of synthetic membrane has an asymmetric pore structure: a thinfilm with tight pores backed by a thicker film with wider pores. Thistype of membrane is used for ultrafiltration andreverse osmosis, the porous side faces the feed stream and the tight-pored side faces the product stream. (09 Oct 1997) |
| anterior recess of tympanic membrane | A slitlike space on the tympanic wall between the anterior malleolar fold and the tympanic membrane. Synonym: recessus membranae tympani anterior, Troltsch's pockets, Troltsch's recesses. (05 Mar 2000) |
| anti-basement membrane antibody | Autoantibodies to renal glomerular basement membrane antigens. (05 Mar 2000) |
| anti-basement membrane glomerulonephritis | Glomerulonephritis resulting from anti-basement membrane antibodies, characterised by smooth linear deposits of IgG and C3 along glomerular capillary walls; includes rapidly progressive glomerulonephritis and glomerulonephritis in Goodpasture's syndrome. (05 Mar 2000) |