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Right atrium: Wikis

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Right atrium
Diagram of the human heart (cropped).svg
Anterior (frontal) view of the opened heart. White arrows indicate normal blood flow.
Gray493.png
Interior of right side of heart.
Latin atrium dextrum
Gray's subject #138 528
Artery Right coronary artery
MeSH Right+Atrium

The right atrium (in older texts termed the "right auricle") is one of four chambers (two atria and two ventricles) in the human heart. It receives deoxygenated blood from the superior and inferior vena cava and the coronary sinus, and pumps it into the right ventricle through the tricuspid valve. Attached to the right atrium is the right auricular appendix.

Contents

Nodes

The sinoatrial node (SAN) is located within this chamber next to the vena cava. This is a group of pacemaker cells which spontaneously depolarize to create an action potential. The cardiac action potential then spreads across both atria causing them to contract forcing the blood they hold into their corresponding ventricles.

Embryology

In early life, when a fetus is in the womb, the right atrium has a hole within its septum through to the left atrium, this makes them continuous with each other which is essential for fetal circulation. This junction is called the “Foramen ovale." Once born (usually within 9 month's time) the foramen ovale seals over. This occurs when the first breath is taken; fetal blood flow is reversed and now travels through the lungs no longer requiring the foramen ovale. Therefore it closes and is renamed as the “Fossa ovalis.” The fossa ovalis is seen as an embryonic remnant.

In some cases, the foramen ovale fails to close and is present in 20% of the general population, however it does not cause problems in the vast majority. This is known as a patent foramen ovale.

Within the fetal right atrium, blood from the inferior vena cava and the superior vena flow in separate streams to different locations in the heart, and this has been reported to occur through the Coanda effect.[1]

Supply

The right atrium is supplied with oxygenated blood by the right coronary artery.

The opening of the vein that drains the myocardium itself is found on the right atrium. This is called the coronary sinus.

Additional images

References

  1. ^ Ashrafian H. The Coanda effect and preferential right atrial streaming. Chest. 2006 Jul;130(1):300.

External links

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