57. Thromboembolism of the arteries of the pulmonary circulation: types, causes, significance for the body.

Thromboembolism is the most common type of embolism that occurs when a blood clot or part of it is detached. At the same time, the size of thromboembolism can be different — from emboli, determined only under a microscope, to emboli several centimeters long. Emboli close the lumen of the pulmonary arteries. Foreign particles enter the pulmonary arteries from the venous vessels of the large circulatory circle and the right half of the heart. The consequences depend on the composition, size of the emboli, and their total mass. Multiple embolism of small pulmonary arteries is especially dangerous. Blood flow is disrupted. Blood pressure in the vessels of the small circulatory circle increases, blood flow to the left atrium and ventricle is limited, the stroke and minute volumes of the heart decrease, and blood pressure decreases sharply. Hypotension is a characteristic sign of massive embolism of the vessels of the small circulatory circle. A decrease in blood pressure negatively affects the functional activity of the heart itself due to myocardial hypoxia. A drop in blood pressure is combined with a significant increase in systemic venous pressure with the development of acute right ventricular failure (acute pulmonary heart syndrome).

Pulmonary embolism is accompanied by changes in the gas composition of the blood. Shortness of breath occurs as a reflex reaction to irritation of the chemoreceptors of the reflexogenic zones of the large circulatory system and as a reaction from the receptor fields of the small circulatory system. Shortness of breath helps to enhance blood oxygenation and release it from CO2.

58. Thromboembolism of the arteries of the systemic circulation: causes, significance for the body

Emboli enter the vessels of the large circulatory system in various ways. One of them is the passage of air bubbles through the pulmonary capillary network. They stretch out, take the form of a vessel and flow from a small circle of blood circulation into a large one. In a similar way, drops of fat can penetrate into the bloodstream of a large circle of blood circulation. Lesions of the left half of the heart and its valvular apparatus can cause thromboembolism, tissue embolism. The formation of blood clots in the arteries of a large circle of blood circulation, which occur in animals after the introduction of parasite larvae, causes thromboembolism. The arteries of the large circulatory circle may be the location of tumor cells.

The mesenteric arteries, arteries of the kidneys, spleen, brain, and heart muscle are most often exposed to embolism.

59. Tissue and bacterial embolism: causes, significance for the body.

Tissue (cellular) embolism is possible when tissues are destroyed due to injury or a pathological process, which leads to the entry of pieces of tissue (cells) into the blood.

Emboli can be tumor tissue or complexes of tumor cells during its disintegration, pieces of heart valves in ulcerative endocarditis, brain tissue in head trauma. Embolism of the cerebral tissue of the vessels of the small and large circulatory circles is also possible in newborns with birth trauma. Embolism with amniotic fluid in maternity patients is also referred to as tissue embolism.

More often, tissue (cellular) embolism is observed in the vessels of the large circle, less often in the small circle of blood circulation. A special category of tissue embolism is embolism by malignant tumor cells, since it underlies the hematogenous metastasis of the tumor. Microbial embolism occurs when microbes circulating in the blood clog the capillaries. These can be lumps of glued bacteria or fungi, animal parasites, protozoa. Bacterial emboli are often formed by purulent melting of a blood clot. Bacterial embolism determines the metastasis of pus.

At the site of blockage of the vessel by bacterial emboli, metastatic ulcers are formed: with embolism of small circle vessels — in the lungs, under the pleura, with embolism of large circle vessels — in the kidneys, spleen, heart and other organs.