Pitvarok

Pitvarok, in the context of heart anatomy, refer to the two atria: the right atrium and the left atrium. They are the receiving chambers that collect blood returning to the heart and transfer it to the ventricles through the atrioventricular valves. The right atrium collects deoxygenated blood from the systemic circuit via the superior and inferior vena cavae and the coronary sinus; the left atrium receives oxygenated blood from the lungs via the pulmonary veins. The atria function as reservoirs and contribute to ventricular filling, particularly during diastole.

Anatomy and structure: the right atrium consists of a smooth-walled sinus venarum and a trabeculated inlet with the right atrial appendage containing pectinate muscles; the left atrium is mainly smooth-walled with pectinate muscles in the left atrial appendage. The interatrial septum separates the chambers and bears the fossa ovalis, a remnant of the fetal foramen ovale. The sinoatrial node lies at the high wall of the right atrium near the entry of the superior vena cava; the atrioventricular node is located near the septal tricuspid annulus.

Clinical relevance and development: common issues include atrial septal defects that permit interatrial shunting, atrial enlargement, and atrial fibrillation, which can affect rhythm and hemodynamics. Echocardiography and other imaging modalities are used to assess the atria. Embryology: the atria originate from the primitive atrium; atrial septation involves the septum primum and septum secundum, forming the foramen ovale in fetal life, which closes after birth.