Pathology 🩺 Flashcards
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 are types of infarction?
Red (hemorrhagic) infarct
Pale (anemic) infarct
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 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 does a section in case of spleen infraction show?
- shows in one part normal splenic tissue formed of white and red pulps with splenic trabeculae.
- Other part shows an infarct area formed ghosts of the normal structures with nuclear post necrotic changes.
- An area of congestion and hyperemia lies between the two areas.
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 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 morphology of thrombus?
Grossly and microscopically apparent laminations called lines of Zahn.
What does a section in blood vessel with thrombus show?
- the lumen is occluded by a mass formed of blood elements:
- A pale mass of platelets is attached to the vessel wall (head of the thrombus).
- Pale lines of fused platelets are deposited perpendicular to the head of the thrombus (lines of Zhan).
- In-between lines of Zhan there fibrin network entangling other blood elements.
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 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.
- depends on the size of embolus
