Arterial blood Arterial blood Arterial blood is the oxygenated blood in the circulatory system found in the pulmonary vein, the left chambers of the heart, and in the arteries. It is bright red in color, while venous blood is dark red in color (but looks purple through the translucent skin). It is the contralateral term to "venous blood". Framed in the cardiac cycle, often historically accredited to the Wiggers diagram, arterial blood has just passed through the lungs and is ready to boost oxygen to sustain the peripheral organs. The essential difference between venous and arterial blood is the curve of the
Azygos vein displaced laterally, thereby creating a pleural septum separating an azygos lobe from the upper lobe of the right lung. The anatomy of this blood vessel can be quite variable. In some rare variations for example, it also drains thoracic veins, bronchial veins and even gonadal veins. The vein is so named because it has no symmetrically equivalent vein on the left side of the body. The azygos system is considered to be the azygos vein located from rib number 2 to rib number 4 while the left part of the body has the hemiazygos vein and the accessory hemiazygos vein