4 Learning objectivesIdentify definition,types,causes and effect of both hyperemia & congestion.Understand definition,causes,composition,types,sites and fate of thrombosis.Discuss definition,causes,composition,types,sites and fate of emboli.Understand definition,causes,types and effect of ischemia.Discuss definition,causes,types of infarction.identify definition,causes and types of hemorrhage.Understand definition,causes,types of edema.Discuss definition and types of shock.
5 Hyperemia & Congestion The terms hyperemia & congestion both indicate:a local increase in volume of blood in a particular tissue.Hyperemia is an active process resulting from increased arterial blood inflow because of arteriolar dilatation.- The affected tissue is reddened because of engorgement of tissues with oxygenated blood.Congestion is a passive process resulting from impaired venous outflow from a tissue.- The tissue has a red-blue color due to accumulation of deoxygenated blood.
6 HYPEREMIA Definition: Increase in blood flow to an organ as a result of active dilatation of its arterioles.It is an active process, involving change in the muscle tone of the arterioles (active hyperemia).Types:1- Physiological:- hyperemia in skeletal muscles during exercise ,in the gut following a meal.2- Pathological: e.g. in acute inflammation.
8 VENOUS CONGESTION (Passive Hyperemia) Definition:Increase in venous blood in an organ as result of obstruction of venous outflow.- the veins, venules, & capillaries in the organ become passively dilated (passive hyperemia).- Types: → Localized acutechronicGeneralized acute
9 Acute localized venous congestion Causes: Sudden complete venous obstruction by: thrombosis, ligature.Effects:- Edema may occur in the tissues.- veins and capillaries can rupture → hemorrhage.
10 Chronic localized venous congestion • Causes: Gradual incomplete venous obstruction by:Venous compression by: a tumor, enlarged lymph node orpregnant uterus.• Effects: Chronic dilatation of the veins, venules and capillaries proximal to the obstruction resulting in:1- Edema.2- Stasis predisposes to thrombosis.3- Development of varicoses.
11 Acute generalized venous congestion Causes:- occurs in acute heart failureEffects:rapid generalized congestion in the all viscera.
12 Chronic generalized venous congestion Definition: Gradual congestion affecting the whole venous system in the body.Causes: Right sided heart failureEffects: Dyspnea (due to pulmonary Congestion) Chronic venous congestion in different organs.3- Generalized edema.
14 Definition of thrombosis Thrombosis is:- The formation of a solid mass (compact mass)- Composed of the blood elements.In a blood vessel or heart.In circulating blood.- During life.
15 There are 3 major factors which predispose to thrombosis Causes of thrombosisThere are 3 major factors which predispose to thrombosis(Virchow’s triad)1- Endothelial damage2- Slowing & turbulence of blood flow3- Changes in blood composition
17 Causes of thrombosis 1- Endothelial damage: - Endothelial damage may be:Mechanical, inflammatory, or degenerative The injured endothelium becomes swollen with rough surface.2- Staisis: There is slowing of blood flow in the heart as in mitral stenosis and in blood vessels as in varicose veins.
18 3- Changes in composition of blood: ↑ platelets e.g. after operations.↑ fibrinogen as in pregnancy.↑ R.B.Cs. (polycythemia) → ↑ viscosity of blood → stasis → thrombosis.↑ W.B.C. as in leukemia → ↑ viscosity of blood → stasis → thrombosis.
19 Pathogenesis (Mechanism) of thrombosis: - Platelets leave the blood stream, agglutinate and adhere to the damaged endothelium.They form laminae, which are arranged vertical to the blood stream and called lines of Zhan.- Soon, fibrin accumulates around them with red and white blood cells.
21 Classification of thrombi According to the color & composition of thrombiAccording to the site of thrombus:According to presence or absence of bacteria:
22 According to the color & composition of thrombi: 1- Pale thrombus: formed only of platelets and fibrin.2- Red thrombus: formed mainly of red cells and fibrin.3- Mixed thrombus: containing all blood elements.
23 According to the site of thrombus: 1- Venous thrombus (the most common): formed in veins as in varicose veins and after major abdominal operations Arterial thrombus: found in atherosclerosis and aneurysm.3- Cardiac thrombus: found in the heart, either in the heart chambers called muralthrombus or on the heart valves called vegetations.4- Capillary thrombi
24 According to presence or absence of bacteria: 1- Septic thrombus: containing pyogenic bacteria Aseptic thrombi: without bacteria.
25 1- Venous thrombosis Thrombosis in veins may be either: Thrombosis in veins is more common than other sites because of their slow blood, and thin wall.Thrombosis in veins may be either:ThrombophlebitisPhlebothrombosis
26 2- Arterial thrombosis● Less common than venous thrombosis because of the rapid blood flow in the arteries and the thick elastic arterial wall which resists injury.● Thrombosis occurs in arteries affected by:atherosclerosis, arteritis, & aneurysms(due to stasis, disordered blood flow & roughness of the intima).● Arterial thrombosis → ischemia → infarction.
27 Fate of thrombiIt depends upon its size & whether it is septic or aseptic.● Septic thrombi:Fragments by proteolytic enzymes into septic emboli → payaemic abscesses.● Aseptic Thrombi: may undergo:- Small thrombi is dissolved and absorbed.- Large thrombus undergoes:1- Organization ,canalization .2-Calcification.3- Fragmentation and embolism.
29 Blood ClotA mass of blood elements formed by transformation of fibrinogen to fibrin, in stagnant blood.The clot is dark red with a glistening smooth surface, and is not adherent to the vessel wall.Clotting of blood may be: → Outside the CVSInside the CVS:During life after death(e.g. in stagnant blood) (postmortem clots)red yellow
30 Difference between thrombus and clot: 1- Occurs in stagnant blood during life or after death2- Loosely attached3- Soft and moist4- Red and yellow5- No lines of Zhan1- Occurs in circulating blood during life2- Firmly attached3- Friable and dry4- Pale, pale red or red5- May show lines of Zhan
32 Embolism● DefinitionEmbolus: An insoluble (solid, liquid or gaseous) mass circulating in the blood stream.Embolism: Is the process of impaction of the embolus in a narrow vessel.
33 Embolism ● Causes & Types: 1- Detached thrombi (thrombo-embolism) 2- Fat embolism: The fat of the bone marrow reaches the circulation after fracture of bones.3- Air embolism: due to injury of neck & chest veins.4- Parasitic emboli: e.g. bilharzial worms and ova.5- Tumor emboli: groups of tumour cells penetrate the wall of blood vessels especially veins.6- Amniotic fluid embolism during labour.
34 1- Detached thrombi (thromboembolism) Sites of impaction:1- Pulmonary embolism :the embolus get impacted in pulmonary blood vesseles.2- Portal embolism : the embolus coming from gastrointestinal organs get impacted in the portal veins .3- Systemic embolism : here the embolus get impacted in any blood vessel in systemic circulation.
35 Effects of thromboemboli Effects depends upon:1- Size of the embolus.2- Nature of the embolus (septic or aseptic).3- State of the collateral circulation in the affected site.Effects of pulmonary embolism:Big embolus Medium sized embolus Small embolus
36 Effects of thromboemboli Effects depends upon:1- Size of the embolus.2- Nature of the embolus (septic or aseptic).3- State of the collateral circulation in the affected site.Effects of pulmonary embolism:Big embolus Medium sized embolus Small embolusAcute Rt sidedHeart failureSudden death
37 Effects of thromboemboli Effects depends upon:1- Size of the embolus.2- Nature of the embolus (septic or aseptic).3- State of the collateral circulation in the affected site.Effects of pulmonary embolism:Big embolus Medium sized embolus Small embolusAcute Rt sided healthy lungHeart failureno effectSudden death
38 Effects of thromboemboli Effects depends upon:1- Size of the embolus.2- Nature of the embolus (septic or aseptic).3- State of the collateral circulation in the affected site.Effects of pulmonary embolism:Big embolus Medium sized embolus Small embolusAcute Rt sided healthy lung congested lungHeart failureno effect lung infarctionSudden death
39 Effects of thromboemboli Effects depends upon:1- Size of the embolus.2- Nature of the embolus (septic or aseptic).Effects of pulmonary embolism:Big embolus Medium sized embolus Small embolusAcute Rt sided healthy lung congested lung no effectHeart failureno effect lung infarctionSudden death
40 Fat embolism Rare condition Causes include: (1) Bone fractures and crush limb injuries.(2) Trauma to adipose tissue (infl. or burns).(3) Trauma to a grossly fatty liver.(4) Major surgery.
41 Ischemia Definition: Types: Ischemia may be either: Deficient arterial blood supply to an organ or tissue due to partial or complete occlusion of its artery.Types: Ischemia may be either:1- Acute ischemia(complete or sudden ischemia)2- Chronic ischemia(partial or gradual ischemia)
42 Acute ischemia Causes: Sudden complete arterial occlusion by: 1- Thrombosis or embolism. (most common)2- Surgical ligature of the artery.Effects: :● Sudden occlusion of arteries→ infarction .
43 Chronic Ischemia Causes: Incomplete arterial occlusion by: 1- Atherosclerosis.2- Pressure on the artery by enlarged lymph node, tumor ... etc.Effects:pain on exercise: angina pectoris, intermittent claudication.cellular degeneration, atrophy followed by fibrosis.
45 Infarction Definition An infarct is an area of coagulative necrosis (liquefactive in the brain) caused by sudden ischemia.
46 InfarctionCauses1- Thrombosis that may occur inside diseased arteries.2- Embolism.
47 Types of infarcts: 1- Red infarcts (hemorrhagic): - Occur in vascular organs as the lung, liver and intestine.- The red color is due to hemorrhage in the substance of the infarct.2- Pale infarcts:- Are more common and occur in firm and less vascular organs as the kidney, heart and spleen.3- Liquefactive infarcts:- Occur in the brain and spinal cord.
54 Fate of the infarct Small infarct: Large infarct: Necrotic tissues are removed by macrophages, granulation tissue fills the defect followed by fibrosis.Large infarct:Gets surrounded by a fibrous capsule and its substance may show dystrophic calcification.
56 HAEMORRHAGE Definition: Escape of blood outside the blood vessels or cardiac chambers.(loss of blood from circulation)
57 Causes of haemorrhage1- Trauma: involving the heart and blood vessels.2- Diseases of blood vessels:a) Hypertension.b) Varicose veins: as piles.c) Degeneration: as atheroma and aneurysm.d) Infection: as tuberculosis.e) Malignant cells invading blood vessels.3- Hemorrhagic blood diseases: as haemophilia, leukemia and scurvy.
58 Types of haemorrhage External haemorrhage Internal haemorrhage Interstitial haemorrhage
59 1- External haemorrhage Escape of blood outside the body.1- Epistaxis: Bleeding from the nose.2- Hemoptysis: Coughing of blood.3- Hematemesis: Vomiting of blood.4- Melena: Presence of dark digested blood in stools.5- Bleeding per rectum: passage of red blood with stool6- Hematuria: Blood in urine.7- Menorrhagia: Excessive or prolonged menstrual bleeding.8- Metrorrhagia: Irregular uterine bleeding unrelated to menses9- Bleeding from skin
60 2- Internal haemorrhage Bleeding into body cavities.1- Hemothorax: Hge into the pleural sac.2- Hemopericardium: Hge. into pericardial sac.3- Hemoperitoneum: Hge. into peritoneal sac.4- Hematocele: Hge. into tunica vaginalis sac.5- Hemoarthrosis: Hge. into a joint cavity.
61 3- Interstitial haemorrhage Bleeding into interstitial tissue spaces.1- Petechial haemorrhage:escape of small amount of blood of capillary origin → small spots of haemorrhage.2- Ecchymosis:escape of moderate amount of blood → a bigger patch of haemorrhage.3- Hematoma:escape of large amount of blood causing a swelling.
62 - Interstitial haemorrhage is at first dark red (arterial blood) or bluish (venous blood). - Then, hemoglobin breaks down into biliverdin and hemosiderin.- BiIiverdin gives the area a green color but is soon absorbed in the blood.- The hemosiderin left gives the area a brown color and is gradually removed by macrophages, so the color changes to yellow and gradually fades away.
63 Effects of haemorrhage ● Small amount: No effect.● Repeated small amounts (chronic hge):- Causes microcytic hypochromic anemia.- e.g. in piles and peptic ulcers.● Massive amount: → hemorrhagic shock.
64 EdemaDefinitionCausesClassificationPathological features
65 Edema Definition: - Edema fluid may be either transudate or exudate. - Pathological accumulation of excess fluids in the interstitial tissue spaces and serous sacs.- Edema fluid may be either transudate or exudate.
66 Transudate Exudate Caused by conditions other than inflammation Occurs in cases of inflammation.Low protein content(below 3 gm%).High protein content(4-8 gm%).Specific gravity below 1015.Specific gravity above 1018.Does not clot on standing. (no fibrinogen)Clots on standing(presence of fibrinogen)No inflammatory cells.Contains inflammatory cells.
67 Causes of edema 1- Increased capillary hydrostatic pressure: occurs in cases of : - venous congestion (generalized or localized)- sodium & water retention → ↑ blood volume2- Decreased plasma colloid osmotic pressure:occurs in cases of hypoproteinemia (fall of total plasma proteins below 2.5 gm% or fall of serum albumin below 1.5 gm%)3- Increased capillary permeability:- Caused by toxins, hypoxia, & chemicals (e.g. histamine in acute infl.).- Escape of proteins into Interstitial fluid → ↓ plasma osmotic pressure & ↑ tissue osmotic pressure → further edema.
68 4- Lymphatic obstruction - Lymphatic obstruction causes lymphatic edema (lymphedema).- It is caused by:1- Lymphangitis and lymphadenitis as in Filariasis→ elephantiasis.3- Mechanical compression of lymphatics e.g. by tumors.4- Lymphatic permeation by malignant cells.5- Post-irradiation fibrosis in lymphatics & LNs.6- Surgical removal of the lymph nodes.
69 Classification of edema According to the site of edema:1- Localized edema: e.g inflamatory edema,lymphatic edema.2- Generalized edema (anasarca) e.g in heart failure, renal failure,neutritional edema due to hypoproteinemia.According to consistency of edema:1- Pitting edema (Soft edema):2- Non-Pitting edema (Hard edema)e.g lymphatic edema..
70 Pitting edema The accumulated fluid can be easily moved on pressing the affected part, leaving a pit at site of pressure(it pits on pressure).This is because the edema fluid has low protein content → it is present free in the tissue spaces.Occurs when edema fluid is transutade:1- All types of generalized edema(cardiac, renal and nutritional edema).2- Localized edema due to venous obstruction
71 Non-Pitting edema The edematous part does not pit on pressure. This is because the edema fluid is united with the tissue elements.Occurs in cases oflymphatic edema.