Venasystemen
Venasystemen refers to the network of veins in the circulatory system responsible for returning deoxygenated blood from the body's tissues back to the heart. These vessels differ from arteries in their structure, generally having thinner walls and containing valves to prevent the backflow of blood, especially in areas against gravity. The venous system is broadly divided into the systemic and pulmonary circuits. The systemic venous system collects blood from organs and limbs, while the pulmonary venous system carries oxygenated blood from the lungs to the heart. Key components of the systemic venous system include the superior vena cava, which collects blood from the upper body, and the inferior vena cava, which collects blood from the lower body. Smaller veins merge into larger ones as they approach the heart. The pressure within veins is significantly lower than in arteries, and blood flow is aided by muscle contractions, breathing movements, and the aforementioned venous valves. Disruptions to the proper functioning of venasystemen can lead to various conditions, such as varicose veins or deep vein thrombosis.