Pathology 🩺 Flashcards
What is the definition of thrombosis?
Formation of a compact mass composed of the circulating blood elements inside a vessel or a heart cavity during life.
What are the causes and pathogenesis of thrombosis?
(Virchow’s triad)
- Roughness of the intima (Endothelial injury).
- Slowing of blood flow (stasis). “Bed rest”
- Changes in the composition of blood (hypercoagulability). “Inherited or acquired (due to cancer)”
What is the morphology of thrombosis?
Grossly and microscopically apparent laminations called lines of Zahn, which are pale platelet and fibrin deposits alternating with darker red cell-rich “RBCs and WBCs” layers.
What are the types of thrombosis?
A) According to site:
1. Venous thrombosis (phlebothrombosis): deep vein thrombosis in the lower limb
- Arterial thrombi: As in coronary, cerebral, & femoral arteries
- Heart chambers or in the aortic lumen are mural thrombi
B) Presence or absence of organism (infection): Septic “due to infection at the site of thrombosis” or Aseptic
What are the fate and complications of thrombosis?
1) Septic thrombus: fragmented by proteolytic enzymes → septic emboli → pyaemic abscesses.
2) Aseptic thrombus: fate depends upon its size
a. if small in size: Dissolution: dissolved and absorbed.
b. if large in size: (PEOC)
1. Propagation: Thrombi accumulate additional platelets and Fibrin
2. Embolization: Aseptic emboli → ischemia.
3. Organization “Replaced by fibrous tissue” & Recanalization
4. Calcification.
What is the definition of embolism?
It is the circulation of insoluble material (solid, liquid, or gaseous) in the blood and its sudden impaction in a narrow vessel.
What are the types of emboli?
1- Thrombo-embolism. 2- Fat embolism. 3- Tumor emboli. 4- Parasitic emboli. 5- Air embolism. 6- Amniotic fluid embolism.
What is the origin of thromboembolism?
A detached thrombus may originate from:
- Systemic veins reach the right side of the heart, then lungs → pulmonary embolism
- Cardiac thrombi: Usually originate in the left side of the heart. They are carried by the systemic arterial circulation to impact any organ (spleen, kidney, brain…etc.)
- Portal vein or its branches passes to the liver (portal embolism).
What are common sites for fat embolism? “Injury in BV + Fat source”
Common in sites containing fat such as; Bone fractures & abdomen due to acute pancreatitis
What do fat globules enter through?
ruptured veins
What is the definition of tumor emboli?
Malignant “not just neoplastic” cells pass as emboli in the circulation and give metastases in the organs.
What forms parasitic emboli?
Bilharzial ova and worm
Is amniotic fluid “contains epithelium” embolism rare or common? And when does it occur?
Rare
Occurs during delivery→ fatal pulmonary embolism.
What is the definition of air embolism?
Sudden admission of 100 cc air in the bloodstream —->sudden death.
The air may block the right ventricle or pulmonary arteries —> acute heart failure.
What are the causes of air embolism?
- Injury of large neck veins → gaping (because they are embedded in the fascia that prevents their collapse) → air is sucked into the vessels then the heart.
- Faulty technique during blood transfusion.
- Criminal abortion (air passes into uterine veins). “Using a tool that damages the BV”
- Caisson’s disease
What is caisson’s disease?
A type of air embolism occurs when deep divers work under high atmospheric pressure, where their nitrogen gas is dissolved in the tissues and blood.
Sudden decompression i.e. sudden ascent produces nitrogen bubbles which act as gas emboli.
What is the effect of embolism?
emboli lodge in vessels too small to permit further passage —-> partial or complete vascular occlusion ——>ischemic necrosis (infarction) of the tissue supplied by this vessel.
What does the effect of embolism depend on?
1- Size of embolus.
2- Nature of the embolus: septic (pyemic abscess) or aseptic (infarction).
3- State of the collateral circulation in the affected organ.
What are the sources of pulmonary embolism?
- Mainly arises from recent thrombi of calf veins in lower limbs (Most common).
- Thrombi in the Rt. side of the heart e.g. in cases of Rt. sided heart failure.
What are the effects of pulmonary embolism?
Depends on the size of the embolus
What are the effects of pulmonary embolism in the case of large embolus?
Occludes the pulmonary trunk or one of its main branches produces sudden death (no time for infarction)
What are the effects of pulmonary embolism in the case of a medium-sized embolus?
If the lung is healthy, no effect will occur as the lung has a double blood supply (pulmonary and bronchial arteries).
If the lung suffers from chronic venous congestion, lung infarct occurs. “ And the patient needs observation as he has hypercoagulability”
What are the effects of pulmonary embolism in the case of recurrent small-sized embolus?
Produce pulmonary hypertension due to lung fibrosis “resists blood flow” and right-sided heart failure “higher work done to overcome resistance” (cor-pulmonale).
What is the definition of ischemia?
Decrease of blood supply to a part of tissue due to occlusion of its artery.
What are the types of ischemia?
- Sudden (acute) ischemia: Thrombosis Embolism Arterial spasm Surgical ligature Twisting of the organ’s pedicle
- Gradual (chronic) ischemia: Pressure on the artery by tumor or enlarged L.N.
What do the effects of vascular occlusion depend on?
The effects of vascular occlusion range from no or minimal effect to death of a tissue or person depending on:
•Nature of the vascular supply (end artery or dual blood supply).
- Rate of vascular occlusion. “Acute or chronic”
- Vulnerability of tissue to hypoxia: Neurons (3 to 4 minutes), Myocardial cells (20 to 30 minutes).
- Oxygen content of the blood.
What is the definition of infarction?
It is an area of coagulative necrosis (liquefactive in the brain) due to inadequate blood supply to the affected area.
What is an example of ischemic necrosis?
Infarct
What are types of infarction?
Red (hemorrhagic) infarct
Pale (anemic) infarct:
Where does red hemorrhagic infarct occur?
- loose tissues (allow the collection of blood in the infarcted area)
- Vascular organs such as lung and intestine (dual blood supply)
- Previously congested tissue. “Nutmeg liver”
- Reperfusion of previously ischemic tissue
- Occlusion of a vein
Where does pale anemic infarct occur?
- Occurs in solid and less vascular organs like the kidneys, spleen, and heart
- arterial occlusion
- end arterial supply
What type of infarct could occur in the brain and spleen?
Infarction of the brain and spleen may be pale or red.
What is N/E of infarction?
• Size of infarct area is related to
➢size of the obstructed artery
➢susceptibility of the tissue to ischemia.
• Wedge-shaped (pyramidal) the arteries have
a fan-like distribution, The base is directed towards the surface of the organ and the apex is deep.
• Subcapsular:
raised when recent (due to edema), depressed when healed (due to fibrosis)
- Surrounded by a red zone of hyperemia (inflammation)
- Firm (soft in the brain)
- Sero-fibrinous inflammation of overlying serosa.
What is M/E of infarction?
Area of coagulative necrosis (liquefactive in the brain) surrounded by a zone of acute inflammation (Hyperemia).
What is the fate of infarction?
• Small infarct:
Necrotic tissue is removed by macrophages, Granulation tissue fills the defect followed by fibrosis.
• Large infarct:
- surrounded by a fibrous capsule
- dystrophic calcification.
• In the brain (due to high lipid content): it leaves a cyst surrounded by glial tissue.
What is the definition of gangrene?
A type of necrosis most often affects the lower extremities or bowel and it is secondary to vascular occlusion. And it is associated with a saprophytic bacterial infection.
What are the types of gangrene?
Dry and wet
Where does dry gangrene start and what causes it?
Begins in the distal part of a limb due to ischemia.
What is the rate of spread of dry gangrene?
Slow until it reaches a point where the blood supply is adequate to keep the tissue viable.
In Which type of gangrene is the line of separation formed between the gangrenous part and the viable part?
Dry Gangrene
What is the rate of development of wet gangrene and what causes it?
Develops rapidly due to blockage of venous and arterial blood flow (from thrombosis or embolism).
What are the characteristics of the affected parts with wet gangrene?
The affected part is stuffed with blood which favors the rapid growth of putrefactive bacteria.
What is the characteristic thing for wet gangrene?
The toxic products formed by bacteria are absorbed causing profound systemic manifestations of septicemia, and finally death.
What are examples of wet gangrene?
- Diabetic foot: High sugar content in the necrotic tissue which favors the growth of bacteria.
- Bedsores: Bed-ridden patient due to pressure on sites like the sacrum, buttocks, and heels
Compare between dry and wet gangrene according to:
Sites Cause Progression Line of demarcation Gangrenous part Putrefaction and bad odor Toxemia
“SCG PP LT”
A- Extremities e.g. lower limb
A- Internal organs e.g. intestine, lung.
Extremities in crush injury and diabetes.
B- Gradual arterial obstruction
B- Sudden arterial and venous obstruction.
C- Slowly Present
C- Rapid Absent
D- Black, Dry, and mummified
D- Swollen, edematous with ulcerated skin.
E- Minimal due to lack of fluids Mild
E- Maximal
F- Mild
F- Severe and marked
What is the definition of gas gangrene?
A special form of wet gangrene is caused by gas-forming clostridia (gram-positive anaerobic bacteria).
How do gas-forming Clostridia enter the tissues?
through open contaminated wounds, especially in the muscles, or as a complication of operation on the colon which normally contains clostridia.
What do Gas forming Clostridia produce?
- It produces various toxins which produce necrosis and edema locally.
- Also absorbed producing profound systemic manifestations.
What do both hyperemia and congestion indicate?
Both indicate a local increased volume of blood in a particular tissue.
What is the definition of hyperemia?
it is an active process that result from increased blood flow due to arteriolar dilation.
What are the causes of hyperemia?
- Physiological e.g. Muscular Exercise, emotion& exposure to heat
- Pathological e.g. Acute inflammation& fever. “VD to allow the Flow of immune cells”
- The affected tissue is red because of engorgement with oxygenated blood.
What is the definition of congestion?
Is a passive type of hyperemia due to obstructed venous flow of the tissue.
What are the causes of congestion?
( pathologic only )
- Acute congestion - Sudden right sided heart failure. “Leads to stopping of Venus outflow” - Shock.
- Chronic congestion
- Localized….pulmonary congestion in left sided heart failure.
- Generalized….all organs (including liver) in right sided heart failure.
-Affected organ is blue red “lung congestion” in color due to increased non-oxygenated blood.
What is the causes of CVC of the liver? “Generalized”
right-sided heart failure.
What are the pathogenesis of CVC of the liver?
During the early stages:
- The central part of hepatic lobule is affected with dilated central vein “due to blood” “from hepatic artery” and adjacent blood sinusoids “from central vein” and appear deep red in color.
- The mid zone of the lobule suffer hypoxia “as the blood is deoxygenated” and shows fatty change and appear yellow in color.
- The alternating red and yellow color resemble the nutmeg seed (nut meg liver).
“Periphery isn’t affected”
During late stages of the disease,
- The central cells become necrotic with destruction of the reticular framework. This area of necrosis will be replaced by fibrosis.
- This is called cardiac cirrhosis.
What are the causes of CVC of the lung? “Localized”
1- Left sided heart failure..
2- Mitral stenosis
What is the pathogenesis of CVC of the lung?
In early stage:
- Congestion and distention “increased hydrostatic pressure” of alveolar capillaries leads to transudation of fluid into alveolar spaces
- Rupture of capillaries leads to passage of RBCs into the alveoli.
- Phagocytosis and degradation of red cells result in intra-alveolar hemosidrin-laden macrophages “due to HB” called Heart failure cells.
- At this stage the lungs are “EHBO”
- Enlarged
- Heavy “Due to transudate and blood”
- Bluish-red in color “deoxygenated”
- C/S oozes bloody froth. “Bubbles of air”
In late stage:
-Fibrosis of interstitium & hemosidrin deposition results in Brown induration “fibrosis” of the lung.
- At this stage the lung appears *dark brown
- firm consistency (indurated) due to associated fibrosis.
What is the definition of edema?
- Pathological accumulation of excess fluids in the interstitial tissue spaces or body cavities “pleura, peritonitis and pericardium”
where does fluid accumulates in case of edema?
Fluid is outside cells and outside vascular structures
What is the pathogenesis of edema? “Inc filtration or dec Absorbtion or problem in lymphatics”
- Increased intravascular hydrostatic pressure: due to venous obstruction “congestion”
- Decreased plasma oncotic pressure:
A)Decrease protein synthesis as in liver disease
b) Protein loss as in renal disease - Lymphatic obstruction: due “to SC 4I”
a) Congenital absence of the lymphatics.
b) Surgical removal of LNs. “Edema at that place”
c) Infection: Filariasis.
d) Tumor infiltration. “Obstruction”
e) Irradiation.
f) Inflammation (lymphangitis) - Increased vascular permeability as in acute inflammation
- Sodium retention as in impaired renal function.
What is edema classified according to?
1- According to the site of edema
2- According to consistency of edema
3- According to edema fluid
What are the types of edema according to the site?
1- Localized edema
2- Generalized edema (anasarca) “central affection”
What are types of local edema?
Inflammatory “exudate”
obstructive (Venous “transudate” or lymphatic “lymph” ) (lymphedema)
What are the types of generalized edema?
Cardiac, renal, hepatic and nutritional (hypoproteinemia) “low protein which decreases oncotic pressure”
What are the types of edema according to consistency?
1- Pitting edema: When pressure is applied to an area of edema a depression or dent results as excessive interstitial fluid is forced to adjacent areas.
2- Non-Pitting edema .
What are the causes of non-pitting edema?
1) Inflammatory edema (exudate)
2) Lymphatic edema (Lymph)
“Contain fibers”
What are pitting edemas?
Generalized and venous localized
