Atrium (heart)

Front view of heart showing the atria
Right heart anatomy
left atrial appendage shown at upper right
CT scan of the chest showing a thrombus in the left atrial appendage (left: axial plane, right: coronal plane)

One of two upper chambers in the heart that receives blood from the circulatory system.

- Atrium (heart)

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Inferior vena cava

Anterior (frontal) view of the opened heart. White arrows indicate valid blood flow.
Branches of Inferior Vena Cava
Inferior vena cava
Inferior vena cava front view
Image of an inferior vena cava filter
Image showing an inferior vena cava filter in its position

The inferior vena cava is a large vein that carries the deoxygenated blood from the lower and middle body into the right atrium of the heart.

Mitral valve

One of the four heart valves.

Anterior (frontal) view of the opened heart. White arrows indicate normal blood flow. (Mitral valve labeled at center right.)
Operative view of the mitral valve with a chordal rupture "fail" of the anterior leaflet
3D Medical Animation still shot of Mitral Valve Prolapse
The left side of the heart. The mitral valve, as well as the chordae tendinae are visible as white strings. These connect to the papillary muscles visible attaching to the muscular ventricle.
Mitral annulus
The human heart, viewed from the front. The mitral valve is visible on the right as the "bicuspid valve"
The chest, showing surface relations of bones, lungs (purple), pleura (blue), and heart (red). Heart valves are labeled with "B", "T", "A", and "P".
Mitral valve, viewed in a cadaver specimen from within the left atrium.

It has two cusps or flaps and lies between the left atrium and the left ventricle of the heart.

Superior vena cava

The superior vena cava drains from the left and right brachiocephalic veins into the right atrium
The thorax, viewed from the front, showing the superior vena cava between the heart and lungs.
Heart seen from above, with the valve-less entry of the superior vena cava visible on the right.
Superior vena cava in a cadaveric specimen.
Cross-section of the thorax showing the formation of the superior vena cava.

The superior vena cava (SVC) is the superior of the two venae cavae, the great venous trunks that return deoxygenated blood from the systemic circulation to the right atrium of the heart.

Pulmonary circulation

Division of the circulatory system in all vertebrates.

Human pulmonary circulation. Oxygen-rich blood is shown in red; oxygen-depleted blood in blue
3D rendering of a high resolution computed tomography of the thorax. The anterior thoracic wall, the airways and the pulmonary vessels anterior to the root of the lung have been digitally removed in order to visualize the different levels of the pulmonary circulation.
Image showing main pulmonary artery coursing ventrally to the aortic root and trachea. The right pulmonary artery passes dorsally to the ascending aorta, while the left pulmonary artery passes ventrally to the descending aorta.
The opening page of one of Ibn al-Nafis's medical works

This blood then enters the left atrium, which pumps it through the mitral valve into the left ventricle.

Tricuspid valve

On the right dorsal side of the mammalian heart, at the superior portion of the right ventricle.

Anterior (frontal) view of the opened heart. White arrows indicate normal blood flow. (Tricuspid valve labeled at bottom left.)
Tricuspid valve. Deep dissection.
Tricuspid valve marked in yellow.
Diagram of tricuspid insufficiency/regurgitation. Marked in black arrow.

The function of the valve is to prevent back flow (regurgitation) of blood from the right ventricle into the right atrium during right ventricular contraction: systole.

Pulmonary vein

The pulmonary veins are the veins that transfer oxygenated blood from the lungs to the heart.

Anterior (frontal) view of the opened heart. White arrows indicate normal blood flow.
Computed tomography of a normal lung, with different levels of pulmonary veins.
Bronchial anatomy
Transverse section of thorax, showing relations of pulmonary artery.
Pulmonary vessels, seen in a dorsal view of the heart and lungs.

The largest pulmonary veins are the four main pulmonary veins, two from each lung that drain into the left atrium of the heart.

Atrial septal defect

Illustration of an atrial septal defect.
Patent foramen ovale
Ultrasound picture of the heart, seen in a subcostal view: The apex is towards the right, the atria are to the left. ASD secundum seen as a discontinuation of the white band of the atrial septum. The enlarged right atrium is below. The enlarged pulmonary veins are seen entering the left atrium above.
Abnormal chest X-ray as seen in a patient of atrial septal defect
The Amplatzer Septal Occluder is a device specifically designed to close an ASD
Amplatzer PFO Occluder in heart
Illustration depicting surgical patch closure of ASD
Illustration depicting surgical device closure of ASD
Heart of human embryo of about 35 days
Atrial septal defect with left-to-right shunt
Illustration depicting atrial septal defect

Atrial septal defect (ASD) is a congenital heart defect in which blood flows between the atria (upper chambers) of the heart.

Sinoatrial node

Sinoatrial node shown at 1. The rest of the conduction system of the heart is shown in blue.
Figure 2: Low magnification stained image of the SA node (center-right on image) and its surrounding tissue. The SA node surrounds the sinoatrial nodal artery, seen as the open lumen. Cardiac muscle cells of the right atrium can be seen to the left of the node, and fat tissue to the right.
Figure 3: Sinoatrial node action potential waveform, outlining major ion currents involved (downward deflection indicates ions moving into the cell, upwards deflection indicates ions flowing out of the cell).
Schematic representation of the atrioventricular bundle

The sinoatrial node (also known as the sinuatrial node, SA node or sinus node) is a group of cells known as pacemaker cells, located in the wall of the right atrium of the heart.

Ventricle (heart)

One of two large chambers toward the bottom of the heart that collect and expel blood towards the peripheral beds within the body and lungs.

Computer generated animation of cut section of the human heart showing both ventricles.
Heart section showing ventricles and ventricular septum
Wiggers diagram of various events of a cardiac cycle, showing left ventricular volume as a red trace.
Partial Wiggers diagram. Red = aortic pressure Blue = left ventricular pressure Yellow = left atrial pressure.

The blood pumped by a ventricle is supplied by an atrium, an adjacent chamber in the upper heart that is smaller than a ventricle.

Pulmonary artery

Artery in the pulmonary circulation that carries deoxygenated blood from the right side of the heart to the lungs.

Anterior (frontal) view of the opened heart. White arrows indicate normal blood flow. (Pulmonary artery labeled at upper right.)
Volume rendering of a high resolution CT scan of the thorax. The anterior thoracic wall, the airways and the pulmonary vessels anterior to the root of the lung have been digitally removed to visualize the different levels of the pulmonary circulation.
At the far end, pulmonary arteries (labelled at the bottom) become capillaries at the pulmonary alveoli.
Image showing main pulmonary artery coursing ventrally to the aortic root and trachea, and the right pulmonary artery passes dorsally to the ascending aorta, while the left pulmonary artery passes ventrally to the descending aorta.
Pulmonary circuit
Transverse section of thorax, showing relations of pulmonary artery.
Pulmonary artery
Pulmonary artery.Deep dissection.Anterior view.
CT scan of a normal lung, with different levels of pulmonary arteries.
Bronchial anatomy

The mean pressure is typically 9–18 mmHg, and the wedge pressure measured in the left atrium may be 6–12 mmHg.