- ergometer (ûr-gòm¹î-ter) noun An instrument for
measuring the amount of work done by a muscle or group of muscles.
- [Greek ergon, work + -METER.] er´go·met¹ric
(ûr´ge-mèt¹rîk) adjective 2
- Electron Transport
- electron transport noun Biochemistry. The successive
passage of electrons from one cytochrome or flavoprotein to another by a series of
oxidation-reduction reactions during the aerobic production of ATP, with the electrons
originating from an oxidizable substrate and ultimately being passed to molecular oxygen.
The oxidation-reduction reactions generate the energy required for the production of ATP.
- en·ceph·a·lop·a·thy (èn-sèf´e-lòp¹e-thê) noun --
plural en·ceph·a·lop·a·thies Any of various diseases of the brain.
- en·ceph´a·lo·path¹ic (-le-pàth¹îk) adjective 2
- endorphin (èn-dôr¹fîn), any of a group of NEUROTRANSMITTERS,
affecting mood, perception of pain, memory retention, and learning. Chemically similar to
opium-derived NARCOTICS, endorphins were searched for and found in the 1970s after the
discovery that MORPHINE works by attaching itself to specific receptor sites in the brain.
Endorphins also attach to these receptors and appear to be the brains own natural
painkillers. Besides behaving as pain regulators, endorphins are believed to contribute to
euphoric feelings such as the "runners high" experienced after prolonged
- enzyme (èn¹zìm´), protein functioning as a biological
CATALYST. Enzymes accelerate (often by several orders of magnitude) chemical reactions in
the cell that would proceed imperceptibly or not at all in their absence. The enzyme is
not permanently modified by its participation. Most enzymes demonstrate great specificity,
reacting with only one or a small group of closely related chemical compounds; several
enzymes are sometimes required for efficient catalytic function. Some enzymes depend on
the presence of COENZYMES for their function. For the enzyme to continue to be effective,
its three-dimensional molecular structure must be maintained. Over 1,500 different enzymes
have been identified, and the exact sequence of AMINO ACIDS (subunits of a protein) has
been determined for many through the technique of X-RAY CRYSTALLOGRAPHY. It is believed
that an enzyme functions by attaching the molecule it acts on to a specific molecular
site, so that the electrostatic forces of nearby atoms sharply reduce the energy needed to
cleave and re-form the appropriate chemical bonds. 1
- ex·og·e·nous (èk-sòj¹e-nes) adjective
- 1. Biology. Derived or developed from outside the body;
- 2. Medicine. Having a cause external to the body. Used of
diseases. [French exogène : Greek exo-, outside. EXO- + French -gène,
-gen.] ex·og¹e·nous·ly adverb