| exit block | Inability of an impulse to leave its point of origin, the mechanism for which is conceived as an encircling zone of refractory tissue denying passage to the emerging impulse. (05 Mar 2000) |
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| exit domain | <molecular biology> One of the two main binding sites on the ribosome molecule. The finished portion of the polypeptide being translated is attached to this site and leaves the ribosome from this site when the entire polypeptide is finished. (09 Oct 1997) |
| exit dose | The exposure dose of radiation leaving a body opposite the portal of entry. (05 Mar 2000) |
| exit pupil | <microscopy> The exit pupil of a lens system is an image of the entrance pupil (hence conjugate to it) and normally should be the image of the limiting diaphragm. In both the microscope and the telescope it is the eyepoint where the beam has its smallest cross-section. It is also called the Ramsden circle or eyepoint. (05 Aug 1998) |
| exitus | An exit or outlet; death. Origin: L. Fr. Ex-eo, pp. -itus, to go out (05 Mar 2000) |