[Significance of functional and nutritive pulmonary circulation for vital reactions in the form of embolisms]

The functional and nutritive circulation in the lungs is connected by anastomoses between the pulmonary and bronchial arteries. The anastomoses have the structure of blocked arteries from which arteriovenous anastomoses proceed to the peribronchial plexus. The pulmonary artery is provided with a flow impulse by the anastomoses, and oxygen-containing blood is admixed with the venous blood, thus forming an "aortalization" in the lungs. By diverting the bloodstream, venous blood can reach the bronchial artery. The peculiarities of the lung circulation are important for vital reactions in the form of macro- and microembolisms. Macroembolisms prove the functionality of the system if branches of the pulmonary artery are closed before the arteries are blocked. A hemorrhagic infarction either arises or does not arise, and the hemorrhagic infarction cannot exceed a certain limit. A microembolism is over and above the anastomoses. If the microembolism is greater, pressure in the arteria pulmonaris can cause blood from the pulmonary artery to overflow into the bronchial artery. Because arteriovenous anastomoses arise from the blocked arteries, microemboli can now reach the systemic circulation. Thus, the system described can explain the passage of microemboli into the systemic circulation, avoiding the capillaries of the lungs; on the other hand, larger microembolisms can prove the functionality of the system.