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]]