Purkinje fibers 396964 225554573 2008-07-14T08:08:21Z Emilyrader 4922346 /* Histology */ {{Infobox Anatomy | Name = Purkinje fibres | Latin = | GraySubject = | GrayPage = | Image = Gray498.png | Caption = Section of the heart showing the [[ventricular septum]]. | Image2 = ECG_Principle_fast.gif | Caption2 = The [[QRS complex]] is the large peak in the diagram at the bottom. | System = | MeshName = | MeshNumber = | DorlandsPre = f_05 | DorlandsSuf = 12361434 | }} ''For the nervous cells, see [[Purkinje cell]]'' '''Purkinje fibers''' (or Purkyne tissue) are located in the inner [[Ventricle (heart)|ventricular]] walls of the [[heart]], just beneath the [[endocardium]]. These fibers are specialized [[myocardium|myocardial]] fibers that conduct an electrical [[stimulus (physiology)|stimulus]] or impulse that enables the heart to contract in a coordinated fashion. ==Histology== [[Image:Purkinje_fibers.jpg|160px|left|thumb|The larger round cells on the right are purkinje fibers.]] Because of their specializations to rapidly conduct impulses (numerous [[sodium ion channel]]s and [[mitochondria]], fewer [[myofibril]]s than the surrounding muscle tissue), Purkinje fibers take up stain differently than the surrounding muscle cells, and on a slide, they often appear lighter and larger than their neighbors. ==Function== Purkinje fibers work with the [[sinoatrial node]] (SA node) and the [[atrioventricular node]] (AV node) to control the [[heart rate]]. During the ventricular contraction portion of the cardiac cycle, the Purkinje fibers carry the contraction impulse from the left and right '''bundle branches''' to the [[myocardium]] of the ventricles. This causes the muscle tissue of the ventricles to contract and force [[blood]] out of the heart — either to the [[Circulatory system#Pulmonary circulation|pulmonary]] circulation (from the right ventricle) or to the [[Circulatory system#Systemic circut |systemic]] circut (from the left ventricle). The impulse through the Purkinje fibers is associated with the [[QRS complex]]. Purkinje fibers also have the ability of automaticity - they generate [[action potential]]s, but at a slower rate than [[sinoatrial node]] and other atrial [[ectopic pacemakers]]. Thus they serve as the last resort when other pacemakers fail. ==Etymology== They were discovered in [[1839]] by [[Jan Evangelista Purkinje]], who gave them his name. ==See also== *[[Electrical conduction system of the heart]] ==External links== *{{eMedicineDictionary|subendocardial+branches+of+atrioventricular+bundles}} * {{UCDavisOrganology|Circulatory/heart/purkinje/purkinje1}} - "Mammal heart, purkinje fibers (LM, Medium)" * {{AnatomyAtlasesMicroscopic|05|78}} * {{LoyolaMedEd|Histo/practical/cardio/hp8-21.html}} *[http://meded.ucsd.edu/hist-img-bank/chapter_3/Slides_43_44_45_cardiac/pages/d.2.44.1.2.htm Histology at ucsd.edu] *[http://science.nhmccd.edu/Biol/cardio/purkinje.htm Histology at nhmccd.edu] {{Heart}} [[Category:Cardiac anatomy]] [[Category:Cardiac electrophysiology]] [[es:Fibras de Purkinje]] [[fr:Fibre de Purkinje]] [[pl:Włókna Purkiniego]] [[zh:浦金氏纖維]]