Skip to Main Content

We have a new app!

Take the Access library with you wherever you go—easy access to books, videos, images, podcasts, personalized features, and more.

Download the Access App here: iOS and Android. Learn more here!

International System of Units

ABBR: SI. An internationally standardized system of units. The basic quantity measured and the names of the units are meter (length), kilogram (mass), second (time), ampere (electric current), kelvin (temperature), candela (luminous intensity), and mole (amount of a substance). All other units of measurement are derived from these seven basic units.

International Union of Pure and Applied Chemistry

ABBR: IUPAC. An organization composed of experts from many countries whose charter is to standardize aspects of the basic science of chemistry, including nomenclature, structural formulae, and so forth.

international unit

ABBR: I.U. An internationally accepted amount of a substance. Usually this form of expressing quantity is used for fat-soluble vitamins and some hormones, enzymes, and biologicals such as vaccines. These units are defined by the International Conference for Unification of Formulae.

image The abbreviation “I.U.” should not be used in the medical record. It is easily mistaken for other symbols or abbreviations; e.g., for the abbreviation for intravenous, “IV.”


(int″ĕr-noor′on″) [interi + neuron] A neuron that is within the central nervous system but not directly connected to the periphery and is neither sensory nor motor. There are two principal types: 1) those that convey information over short distances and are called local interneurons, internuncial neurons, local circuit neurons, or Golgi type II neurons, and 2) those that convey information from region to region and are called relay, principal, projection, or Golgi type I neurons.


(ĭn′tĕr″nĭst) A physician who specializes in internal medicine.


(int′ĕr-nōd″) [inter- + node] The space between adjacent nodes. internodal (int″ĕr-nōd′ăl), adj.


(int″ĕr-noo′klē-ăr) [inter- + nuclear] 1. Between atomic nuclei. 2. Between the outer and inner nuclear layers of the retina.


(int″ĕr-nŭn′shăl) [inter- + L. nuncius, nuntius + +, messenger] Acting as a connecting medium.


(int″ĕr-ŏ-kloo′zăl) [inter- + occlusal] Between the occlusal surfaces or cusps of opposing teeth of the maxillary and mandibular arches. SEE: interdental; interproximal.


(int″ĕ-rō-sep′tiv) [interoceptor] In nerve physiology, pert. to sensations arising from the internal organs, esp. the viscera.


A sensory receptor. SEE: sensory receptor.


(ĭn″tĕr-ŏp″ĕr-ŭ-bĭl′ĭ-tē) [″ + ″] The ability of different software programs, e.g., the ones that drive electronic medical records, to share information with each other.


(int″ĕr-or′bĭt-ăl) [inter- + orbit] Between the orbits of the eyes.

Pop-up div Successfully Displayed

This div only appears when the trigger link is hovered over. Otherwise it is hidden from view.