pathway
[path´wa] a course usually followed. In neurology, the nerve structures through which a sensory impression is conducted to the cerebral cortex (afferent pathway), or through which an impulse passes from the brain to the skeletal musculature (efferent pathway). Also used alone to indicate a sequence of reactions that convert one biological material to another (metabolic pathway).
accessory pathway (
accessory conduction pathway) extra muscle tissue between the atrium and ventricle that bypasses all or part of the normal
conduction system. When the ventricles are activated prematurely via this pathway, initial forces are slow, producing the delta wave of
wolff-parkinson-white syndrome, and
preexcitation is said to exist; the delta wave causes the PR interval to shorten and the QRS interval to broaden.
amphibolic pathway a group of metabolic reactions with a dual function, providing small metabolites for further catabolism to end products or for use as precursors in synthetic, anabolic reactions. The
tricarboxylic acid cycle is an example. See also
anabolism and
catabolism.
biosynthetic pathway the sequence of enzymatic steps in the synthesis of a specific end-product in a living organism.
Embden-Meyerhof pathway the series of enzymatic reactions in the anaerobic conversion of glucose to lactic acid, resulting in energy in the form of adenosine triphosphate (ATP).
final common pathway 1. the motor neurons by which nerve impulses from many central sources pass to a muscle or gland in the periphery.
2. any mechanism by which several independent effects exert a common influence.
pentose phosphate pathway a pathway of hexose oxidation in which glucose-6-phosphate undergoes two successive oxidations by NADP, the final forming a pentose phosphate.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.