يجان سابع ةلاه. م ةثلاثلا ةلحرملا

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1 المرحلة الثالثة م. هالة عباس ناجي فرط الدم واالحتقان Congestion: Hyperemia and Both terms hyperemia and congestion indicate an increased volume of blood in the vessels of particular tissue. Hyperemia: is an active process resulting from increased blood flow due to arteriolar dilation. Congestion: is a passive process resulting from defective venous return from a tissue. فرط الدم ** Hyperemia hyperemia is of two types: 1. Active hyperemia: indicates that the increased volume of blood is of arterial origin. 2. Passive hyperemia ( or passive congestion) or simply congestion: result from interference with venous drainage. - active hyperemia usually associated with inflammation. - All active hyperemia are acute. - It's a method employed by the body to supply additional nutrients and oxygen to the tissues when an increased rate of metabolism is required. - Active hyperemia may be general or local both are acute so this can be divided to: فرط الدم الفاعل العام الحاد Hyperemia: - A Acute General Active This is an increased amount of blood in the arterial system through out the entire individual. e.g. systemic diseases like: ( pasteurellosis and erysipelas) Macroscopically: The arteries are distended with blood. Microscopically: The arteries and capillaries are dilated and filled with blood. It's disappears as soon as the causative agent is removed. فرط الدم الفاعل الموضعي الحاد Hyperemia: B Acute Local Active This is an increased amount of blood in the arterial system within a local area ( leg, stomach, liver or lungs) of an individual. Causes: the causes are either physiological or pathological

2 1. Increase physiological activity which leads to marked increase of arterial blood e.g. : in muscular exercise the arterioles of the muscles become dilated and the capillary bed increases. 2. The stomach and intestines during digestion. 3. The mammary gland to the start of lactation. 4. The genital tract during estrus. 5. Blushing in human. 6. Pathological causes are first step of inflammation. Macroscopically: The part is enlarged, swollen and heavier than normal due to increased amount of blood, color is bright red. Blood vessels are larger and distended with blood. Microscopically: Active hyperemia is difficult to detect in dead animal. االحتقان المنفعل **Passive Congestion two varieties of venous congestion can be recognized: 1. General venous congestion: If the interference is central e.g in the heart or lungs. 2. Local venous congestion: If the interference with the venous flow is located in the vein of an organ or part of the body. األحتقان المنفعل العام الحاد - Acute general passive congestion This is an increase in the amount of blood in the venous side of the circulatory system due to a sudden obstruction to the flow of blood in the heart or lungs. Causes: 1. Degeneration and necrosis of the myocardium. 2. Myocardial infarction (result from thrombus or embolus) 3. Pneumonia. 4. Pulmonary thrombosis or embolism. التامور, pyopericardium التامور المدمى Haemopericardium,موه التامورHydropericardium.5.القيحي. الصدر القيحيpyothorax and الصدر المدمى, Haemothorax موه الصدر.6 Hydrothorax

3 Macroscopically: Organs inside the body have an intense bluish red (cyanotic color) ازرقاق due to the large amount of deoxygenated hemoglobin in the blood (cyanosis). the veins are distended with blood. Organs are enlarged and heavy. Microscopically: veins and capillaries are distended with blood. - Chronic general passive congestion This is an increase in the amount of blood in the venous side of the circulatory system that persist for long period of time and results in permanent alterations (atrophy and fibrosis) in various tissues and organs through out the body. Causes: the lesion have a central location in the heart or lungs. 1. Stenosis of valvular opening. 2. Valvular insufficiency. 3. Myocardial failure ( myocardial degeneration and necrosis) 4. Anomalies of the heart. 5. Constrictive lesions of the pericardium and epicardium such as ( Traumatic Reticulopericarditis TRP in cattle). In the Lung :- 1. Obliteration of the capillary bed. 2. Compression of the major pulmonary vessels by: trauma, cysts or abscess. MORPHOLOGY: Veins through out the body are engorged with blood. The blood has a bluish red cyanotic color due to large amount of poorly oxygenated blood. Prescence of edema in under surface and legs. In the lung: Affected lung in left sided heart failure, the alveolar capillaries are engorged with blood. The hemosiderin released from the disintegrating red cells in phagocytosed by alveolar macrophages (MǾ).

4 The hemosiderin laden macrophages in the alveolar spaces are called ( heart failure cells), then the edematous septa become fibrotic and produce the condition known as ( brown induration of the lung) the brown color is due to hemosiderin. ** Hypostatic congestion:- It s a special form of hyperemia which occurs in the dependent parts of the body of recumbent, weak, sick patients and in animals short time before death. Probably it occurs due to a loss of vascular tone or cardiac weakness. It's also occurs after death in the lowerest parts of body due to the settling of the blood by gravity. النزف Haemorrhage Haemorrhage defined as: the escape of blood from any portion of the blood vascular system. Classification :- 1. According to the location: a. In the body cavities internal haemorrhage b. Outside the body external haemorrhage c. In the tissue spaces interstitial haemorrhage 2. According to the organ : Nose epistaxis Lung haemoptysis Stomach haematomesis Uterus metrorrhagion Intestines melaena Urinary tract haematuria Haemorrhage into the pericardium : haemopericardium. = = peritoneum : haemoperitonium. = = thorax : haemothorax. 3. According to the type of blood vessel: a. Arterial haemorrhage. b. Venous haemorrhage.

5 c. Capillary haemorrhage. 4. According to the size of haemorrhage: a. Petechial haemorrhage: it having a diameter not larger than one millimeter. b. Ecchymoses: are circumscribed, of only few millemeters in diameter. c. Haematoma: if it is big enough to cause a swelling. d. Suffusions: it diffuse, flat, often irregular areas of bleeding. 5. According to the pathogenesis: a. Rhexis: rapid flow of blood through a break or cut in the wall of a vessel. b. Diapedesis: slow oozing of fluid with the escape of blood cells one by one through minute imperfections in the vessel wall. Causes of haemorrhage: The haemorrhage can be results from: 1. Trauma. 2. Erosions or destructions of a vessel wall as in intestinal ulcer. 3. Rupture of a vessel weakened by an aneurysm or atheroma. 4. Increase intravascular tension e.g. : hypertension, chronic venous congestion and.البواسير haemorrhoids 5. Bacterial infections and toxins may destroy the walls of capillaries or venules e.g. : septicemia, anthrax, hog cholera and black leg. 6. Deficiency of oxygen in the blood as in case of asphyxia. Microscopically:- Hemorrhage is recognized by the presence of erythrocytes outside blood vessels. If hemorrhage is recent the erythrocyte are intact and stain sharply. Then due to the action of enzymes and also are degraded تتكسر and phagocytosed by MǾ. the released hemoglobin ( red blue color) is then enzymatically converted into bilirubin ( blue green color) then into hemosiderin appear as golden brown granules that are irregular in both size and they are phagocytosed and retain in macrophages. Hemosiderin contains iron and gives a Prussian blue reaction.

6 Blood Clot and Thrombosis Blood Clots: Blood clots are of two types: 1. Clots formed in the flowing blood stream " Anti mortem" and are called thrombi. 2. Clots not formed in the flowing blood. These include clots formed in the vessels after death, called " post mortem clots" and those formed outside the vessels are result of haemorrhage. Thrombosis: Definition:- Thrombosis means the clotting of circulatory blood in the cardiovascular system during life. Pathogenesis:- Three factors are involved in the process of thrombosis:- 1. Injury of the intima of the vessels:- this is a common cause of thrombosis and may occur by any of the flowing ways: a. Mechanical injury by section, rupture, or torsion of the vessel. b. Degeneration of the vascular endothelium at the site of an atheroma or aneurysm. c. Inflammatory process e.g: phlebitis. d. Parasites. 2. Slowing or stasis of the blood stream: Normally the leukocytes run in the central or axial stream while the red cells run around the leukocytes and are surrounded in turn by the blood platelets. A clear zone of blood plasma is kept in contact with endothelial lining of the vessels. Any change in the velocity of the blood stream disturbs the peripheral clear plasmatic zone and brings the platelets in contact with the vascular surfaces and thus initiates thrombosis. 3. Changes in the composition of blood: a. There is increase in the number of platelets after operations. They become also more fragile and thus under go lysis and release the thromboplastic factor more readily.

7 b. There is increase in the fibrinogen during pregnancy. Formation of a thrombus: 1. The process begins at the point where the intima is injured. 2. Platelets collect and conglutinate at this roughened spot. 3. The agglutinated platelets undergo lysis and release an enzyme called thromboplastin. 4. Thromboplastin + prothrombin + calcium ion Thrombin. 5. Thrombin + fibrinogen Fibrin. 6. Thus a fine network of fibrin forms between the laminae and agglutinated platelets. 7. The newly formed mass or thrombus enlarges gradually in size. Classification of Thombi :- 1. According to the presence or absence of pyogenic bacteria: a. A septic thrombi: are free from pyogenic or other pathogenic microorganisms. b. Septic thrombi: contain pyogenic organisms. c. Parasitic thrombi: are those which contain parasites. 2. According to the mode of it's formation, thrombi can be classified into: a. White thrombus: which consists of masses of platelets and a small amount of fibrin it's observed in the heart and blood vessels (aorta, carotid and femoral arteries). b. Red thrombus: consist of blood platelets, fine network of fibrin in which the blood cells ( erythrocytes and leukocytes) it's usually observed in veins. c. Mixed thrombus: are partly white and partly red, the white portions from the rapid blood flow, and the red portion forms when slow. 3. According to the location within the blood vascular system: a. Cardiac thrombi: located in the heart, valves, walls due to invading by streptococcus and corynebacterium. b. Arterial thrombi: located within the arteries, it's firmly attached to the damaged arterial wall like strongylus(parasite) in horses. c. Venous thrombi: found in veins rarely in animal, common in human.

8 d. Capillary thrombi: located within the capillaries, mostly associated with inflammation. e. Lymphatic thrombi: found in blood vessels and sinuses of lymph nodes and are composed of fibrin. 4. According to location within the heart or blood vessels: a. Mural thrombi: attached to the wall of heart or blood vessels. b. Valvular thrombi: attached to the heart valves. c. Lateral thrombi: attached to one side of vessel wall. d. Occluding thrombi: attached to the entire circumference of the vessel. e. Saddle thrombi: sit on the bifurcation of blood vessels just as saddle straddles the back of a horse. f. Canalized thrombi: in which new blood channels have been formed through the clot, allow a partial restoration of the blood circulation. FATE OF A THROMBUS: 1.In case of an aseptic thrombus, the red cells undergo haemolysis, the white cells disintegrate and all elements fuse together into a hyaline structurless mass (hyaline thrombus). 2.A small thrombus may be then absorbed. 3.A large thrombus undergoes organization. The organization occur by fibroblasts and angioblasts sprout from the underlying intimal tissues, proliferate and push it away to replace the degenerated hyaline material of the thrombus. Later the new formed, very vascular connective tissue (granulated tissue), the granulation tissue penetrates the thrombus at many points at it's periphery. As the newly formed capillaries of this granulation tissue anastemose, blood is forced through them. This is new as a canalized thrombus). Occasionally a venous thrombus may become impregnated with calcium salts (dystrophic calcification).

9 Differences between a thrombus and post mortem clot: Thrombus Post mortem clot 1.pale, red, friable, granular and dry 1.red, soft and moist or yellow and firm, chicken fat clot, formed slowly 2.adherent to the underlying surface. 2. not adherent. 3.when removed leaves a roughened spot at the 3.when removed the underlying vascular place of attachment. surface is smooth and glistening. 4.laminated 4.not laminated 5.it occurs during life. 5.it occurs after death. Emboli and Embolism Definition: an embolus is an insoluble material which circulates in the blood stream until it gets impacted in a vessel which too small to permit their passage. This process of impaction is called embolism. It's intravascular, solid, liquid or gaseous mass that is carried by the blood to a site away from it's point of origin. Emboli may occur within either the arterial or the venous system, and it's almost always lodges in an artery or a capillary since the diameter of these vessels decreases. in domestic animals: embolism almost always occurs in arteries and not in veins, while in human venous embolism is very common. Etiology: 1.Thrombi 2. bacteria 3. parasites 4. neoplasms 5.fibrin. 6. fat emboli. 7. clumps of normal body cells. 8. Air or gas emboli.