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Encyclopedia > Left atrium
Anterior (frontal) view of the opened heart. White arrows indicate normal blood flow.
Gray's Fig. 496 - Interior of left side of heart.

The left atrium is one of the four chambers in the human heart. It receives oxygenated blood from the four pulmonary veins, and pumps it into the left ventricle. Image File history File links Diagram_of_the_human_heart_(cropped). ... Image File history File links Diagram_of_the_human_heart_(cropped). ... Image File history File links Gray496. ... Image File history File links Gray496. ... An illustration from the 1918 edition Henry Grays Anatomy of the Human Body, commonly known as Grays Anatomy after Henry Gray, is an anatomy textbook widely regarded as a classic work on human anatomy. ... In the heart, a ventricle is a chamber which collects blood from an atrium (another heart chamber) and pumps it out of the heart. ... Trinomial name Homo sapiens sapiens Linnaeus, 1758 Humans, or human beings, are bipedal primates belonging to the mammalian species Homo sapiens (Latin: wise man or knowing man) under the family Hominidae (the great apes). ... The heart and lungs, from an older edition of Grays Anatomy. ... General Name, Symbol, Number oxygen, O, 8 Chemical series Nonmetals, chalcogens Group, Period, Block 16, 2, p Appearance colorless (gas) very pale blue (liquid) Atomic mass 15. ... Human blood smear: a - erythrocytes; b - neutrophil; c - eosinophil; d - lymphocyte. ... The pulmonary veins carry blood from the lungs to the left atrium of the heart. ... In the heart, a ventricle is a chamber which collects blood from an atrium (another heart chamber) and pumps it out of the heart. ...


Blood is pumped through the left atrioventricular orifice, which contains the mitral valve. The left atrium is larger than the right. A normal left atrium may be up to 5.5cm in maximum diameter; any larger than this is a sign of cardiac failure. This may occur in cases of mitral regurgitation. The mitral valve, also known as the bicuspid valve, is a valve in the heart that lies between the left atrium (LA) and the left ventricle (LV). ... Congestive heart failure (CHF) (also called heart failure) is the inability of the heart to pump blood effectively to the body, or requiring elevated filling pressures in order to pump effectively. ... Mitral regurgitation (MR), also known as mitral insufficiency, is the abnormal leaking of blood through the mitral valve, from the left ventricle into the left atrium of the heart. ...


The left atrium of a human faces more or less posteriorly. It is named 'left' based on the chamber's embryological and (putative) evolutionary origin. The term 'base' of the heart sometimes refers to the left atrium, though 'base' is an ambiguous term.


There is a foramen ovale (oval hole) between the right and left atrium in the fetus. After birth, this should close over and become the fossa ovale. If it does not, this is an atrial septal defect (hole in the heart). In the fetus, the right atrium pumps blood into the left atrium, bypassing the pulmonary circulation (which is useless in a fetus). In an adult, a septal defect would result in flow in the reverse direction - from the left atrium to the right - which will reduce cardiac output, potentially cause cardiac failure and in severe or untreated cases, death. Atrial septal defects (ASD) are a group of congenital heart diseases that enables communication between atria of the heart and may involve the interatrial septum. ... Congestive heart failure (CHF) (also called heart failure) is the inability of the heart to pump blood effectively to the body, or requiring elevated filling pressures in order to pump effectively. ...


Attached to the left atrium is the left auricular appendix (auricle). This auricle is a common site for formation of thrombi, which may embolise causing stroke or ischemic gut. Atrial fibrillation makes this more likely. The left auricular appendix (left auricula, left auricle) of the heart is somewhat constricted at its junction with the principal cavity; it is longer, narrower, and more curved than that of the right side, and its margins are more deeply indented. ... A thrombus is the final product of blood coagulation, through the aggregation of platelets and the activation of the humoral coagulation system. ... Atrial fibrillation (AF or afib) is an abnormal heart rhythm (cardiac arrhythmia) which involves the two small, upper heart chambers (the atria). ...


The left atrium is supplied mainly by the left circumflex coronary artery, though the branches are too small to be identified in a cadaveric human heart and are not named. The oblique vein of the left atrium is partly responsible for venous drainage; it derives from the embryonic left superior vena cava. The left coronary artery, also abbreviated LCA, arises from the aorta above the left cusp of the aortic valve. ... Superior vena cava - Wikipedia, the free encyclopedia /**/ @import /skins-1. ...


Animals

Many other animals, including mammals, also have four-chambered hearts, and have a left atrium. The function in these animals is similar. Some animals (amphibians, reptiles) have a three-chambered heart, in which the blood from each atrium is mixed in the single ventricle before being pumped to the aorta. In these animals, the left atrium still serves the purpose of collecting blood from pulmonary veins.


Additional images

See also



 

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