Purkinje fibers

Source: Wikipedia, the free encyclopedia.
For the nervous cells, see Purkinje cell.

Purkinje fibers
Isolated heart conduction system showing Purkinje fibers
The QRS complex is the large peak.
Details
Identifiers
Latinrami subendocardiales
MeSHD011690
TA98A12.1.06.008
TA23961
FMA9492
Anatomical terminology

The Purkinje fibers, named for

heart rhythm.[5]

Histology

Purkinje fiber just beneath the endocardium.

Purkinje fibers are a unique

cardiac end-organ. Further histologic examination reveals that these fibers are split in ventricles walls. The electrical origin of atrial Purkinje fibers arrives from the sinoatrial node
.

Given no aberrant channels, the Purkinje fibers are distinctly shielded from each other by collagen or the cardiac skeleton.

The Purkinje fibers are further specialized to rapidly conduct impulses (having numerous fast

mitochondria, and fewer myofibrils, than the surrounding muscle tissue). Purkinje fibers take up stain differently from the surrounding muscle cells because of having relatively fewer myofibrils than other cardiac cells. The presence of glycogen around the nucleus causes Purkinje fibers to appear, on a slide, lighter and larger than their neighbors, being arranged along the longitudinal direction (parallel to the cardiac vector). They are often binucleated cells.[6]

Function

Heart rate is governed by many influences from the

autonomic nervous system. The Purkinje fibers do not have any known role in setting heart rate unless the SA node is compromised (when they can act as pacemaker cells).[7] They are influenced by electrical discharge
from the sinoatrial node.

Impulse carrying

During the

systemic circulation from the left ventricle.[8]

Replacement pacemaker

Purkinje fibers also have the ability of firing at a rate of 20–40 beats per minute if upstream conduction or pacemaking ability is compromised.[9] In contrast, the SA node in normal state can fire at 60-100 beats per minute.[9] In short, they generate action potentials, but at a slower rate than the sinoatrial node.[9] This capability is normally suppressed. Thus, they serve as the last resort when other pacemakers fail. When a Purkinje fiber does fire, it is called a premature ventricular contraction or PVC, or in other situations can be a ventricular escape.

Etymology

Purkinje fibers are named after the Czech scientist Jan Evangelista Purkyně, who discovered them in 1839.[10]

See also

References

  1. ISBN 978-0-521-15255-6
    .
  2. ISBN 978-0-12-382163-8
    , retrieved November 13, 2020
  3. ISBN 978-0-12-384860-4
    , retrieved November 13, 2020
  4. ^ "Purkinje fiber." The American Heritage® Medical Dictionary. 2007. Houghton Mifflin Company 23 Oct. 2016 http://medical-dictionary.thefreedictionary.com/Purkinje+fiber
  5. ^
    S2CID 239396730
    , retrieved November 13, 2020
  6. ^ Paxton, Steve; Peckham, Michelle; Knibbs, Adele (2003). "histology of purkinje fibres".
  7. S2CID 117312416
    , retrieved November 13, 2020
  8. ^ Podrid, Philip J.; Kowey, Peter R. (2010). Cardiac Arrhythmia, Mechanism, Diagnosis and Management.
  9. ^
    ISBN 978-0-12-374976-5
    , retrieved November 13, 2020
  10. ^ "Jan Evangelista Purkinje | Czech physiologist | Britannica". Britannica.com. Retrieved January 16, 2021.

External links

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