The right atrium is one of four chambers in the hearts of mammals. 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.

The Pulmonary circulation is the portion of the cardiovascular system which transports oxygen-depleted blood away from the heart, to the lungs, and returns oxygenated blood back to the heart.

Hypoplasia can affect the heart, typically resulting in the under development of the right ventricle or the left ventricle. This results in only one side of the heart capable of pumping blood to the body and lungs effectively.

A serous membrane that surrounds the heart allowing it to contract.

Cyanotic heart defects are called such because they result in cyanosis, a bluish-grey discolouration of the skin due to a lack of oxygen in the body. Such defects include persistent truncus arteriosus, total anomalous pulmonary venous connection, tetralogy of Fallot, and tricuspid atresia.

Leghemoglobin is both a nitrogen or oxygen carrier, because naturally occurring oxygen and nitrogen look the same to this protein and a hemoprotein found in the nitrogen-fixing root nodules of leguminous plants.

The endothelium is the thin layer of cells that lines the interior surface of blood vessels, forming an interface between circulating blood in the lumen and the rest of the vessel wall. These cells are called endothelial cells.

Cardiac fibrosis refers to an abnormal thickening of the heart valves due to inappropriate proliferation of cardiac fibroblasts.

Atria of the heart are separated from the ventricles by the coronary sulcus, this contains the trunks of the nutrient vessels of the heart, and is deficient in front, where it is crossed by the root of the pulmonary artery.

These are located at the base of both the pulmonary trunk (pulmonary artery) and the aorta, the two arteries taking blood out of the ventricles. These valves permit blood to be forced into the arteries, but prevent backflow of blood from the arteries into the ventricles. These valves do not have chordae tendineae.

Total anomalous pulmonary venous connection (TAPVC), is a rare cyanotic congenital heart defect (CHD) in which all four pulmonary veins are malpositioned and make anomalous connections to the systemic venous circulation.

Dextrocardia is a congenital defect in which the heart is situated on the right side of the body.

The pulmonary valve is the semilunar valve of the heart that lies between the right ventricle and the pulmonary artery and has three cusps.

Scimitar syndrome, or pulmonary venolobar syndrome, is a rare congenital heart defect characterized by anomalous venous return from the right lung. This anomalous pulmonary venous return can be either partial (PAPVR) or total (TAPVR).

Ebstein anomaly is a congenital heart defect in which the opening of the tricuspid valve is displaced towards the apex of the right ventricle of the heart.

Pulmonary atresia is a congenital malformation of the pulmonary valve in which the valve orifice fails to develop. The valve is completely closed thereby obstructing the outflow of blood from the heart to the lungs.

Transposition of the great vessels (TGV) is a group of congenital heart defects (CHDs) involving an abnormal spatial arrangement of any of the primary blood vessels: superior and/or inferior vena cavae (SVC, IVC), pulmonary artery, pulmonary veins, and aorta.

Persistent truncus arteriosus is a rare form of congenital heart disease that presents at birth. In this condition, the embryological structure known as the truncus arteriosus never properly divides into the pulmonary artery and aorta.

The Brugada syndrome is a genetic disease that is characterised by abnormal electrocardiogram (ECG) findings and an increased risk of sudden cardiac death.

The rare fourth heart sound when audible in an adult is called a presystolic gallop or atrial gallop. This gallop is produced by the sound of blood being forced into a stiff/hypertrophic ventricle.

Capillaries are the smallest of a body's blood vessels and are parts of the microcirculation. They are only 1 cell thick. These microvessels, measuring 5-10 μm in diameter, connect arterioles and venules, and enable the exchange of water, oxygen, carbon dioxide, and many other nutrient and waste chemical substances between blood and surrounding tissues.

The common carotid artery is an artery that supplies the  oxygenated blood to head and neck .It divides in the neck to form the external and internal carotid arteries.

The jugular veins are veins that trasnport deoxygenated blood from the head back to the heart via the superior vena cava.

The tunica externa, also known as the tunica adventitia (or adventitia), is the outermost layer of a blood vessel, surrounding the tunica media. It is mainly composed of collagen and is supported by external elastic lamina.

The middle coat is composed of a thick layer of connective tissue with elastic fibres, intermixed, in some veins, with a transverse layer of muscular tissue.