alternative complement pathway

pathway /path·way/ (path´wa)

1. a course usually followed.

2. the nerve structures through which an impulse passes between groups of nerve cells or between the central nervous system and an organ or muscle.

3. metabolic p..

---

accessory conducting pathway  myocardial fibers that propagate the atrial contraction impulse to the ventricles but are not a part of the normal atrioventricular conducting system.

afferent pathway  the nerve structures through which an impulse, especially a sensory impression, is conducted to the cerebral cortex.

alternative complement pathway  a pathway of complement activation initiated by a variety of factors other than those initiating the classical pathway, including IgA immune complexes, bacterial endotoxins, microbial polysaccharides, and cell walls. It does not include factors C1, C2, and C4 of the classical complement pathway but does include factors B and D and properdin.

amphibolic pathway  a group of metabolic reactions providing small metabolites for further metabolism to end products or for use as precursors in synthetic, anabolic reactions.

circus pathway  a ring or circuit traversed by an abnormal excitatory wavefront, as in reentry.

classical complement pathway  a pathway of complement activation, comprising nine components (C1 to C9), initiated by antigen-antibody complexes containing immunoglobulins IgG or IgM.

common pathway of coagulation  the steps in the mechanism of coagulation from the activation of factor X through the conversion of fibrinogen to fibrin.

Coagulation pathway overview.

efferent pathway  the nerve structures through which an impulse passes away from the brain, especially for the innervation of muscles, effector organs, or glands.

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).

Embden-Meyerhof pathway of glucose metabolism.

extrinsic pathway of coagulation  the mechanism that produces fibrin following tissue injury, beginning with formation of an activated complex between tissue factor and factor VII and leading to activation of factor X, inducing the reactions of the common pathway of coagulation.

final common pathway  a motor pathway consisting of the motor neurons by which nerve impulses from many central sources pass to a muscle or gland in the periphery.

intrinsic pathway of coagulation  a sequence of reactions leading to fibrin formation, beginning with the contact activation of factor XII, and resulting in the activation of factor X to initiate the common pathway of coagulation.

lipoxygenase pathway  a pathway for the formation of leukotrienes and hydroxyeicosatetraenoic acid from arachidonic acid.

Lipoxygenase pathway of leukotriene and hydroxyeicosatetraenoic acid synthesis. HPETE, hydroperoxyeicosatetraenoic acid; HETE, hydroxyeicosatetraenoic acid; LT, leukotriene.

metabolic pathway  a series of enzymatic reactions that converts one biological material to another.

motor pathway  an efferent pathway conducting impulses from the central nervous system to a muscle.

pentose phosphate pathway  a major branching of the Embden-Meyerhof pathway of carbohydrate metabolism, successively oxidizing hexoses to form pentose phosphates.

reentrant pathway  that over which the impulse is conducted in reentry.

---

alternative complement pathway

Properdin pathway Immunology A route of complement activation that occurs independently of complement-fixing antibodies; the ACP is more complex than the classic complement pathway; it requires a 'priming' C3 convertase–C3,Bb, and an 'amplification' C3 convertase–C3b,Bb; in the presence of properdin, C3 convertase is stabilized, activating later complement components, which leads to opsonization, leukocyte chemotaxis, ↑ vascular permeability, and cytolysis; ACP is activated by properdin, IgA, IgG, lipopolysaccharide, and snake venom; both pathways are stimulated by trypsin-like enzymes. Cf Complement.