Haroons notes Flashcards
(126 cards)
What is inflammation?
Acute/chronic tissue injury response
What is the difference between acute and chronic inflammation?
Acute - infections, hypersensitivity (neutrophils)
Chronic - think autoimmunity, recurrent infections (macrophages, lymphocytes)
What are neutrophils like?
‘Polymorphs’ - have many lobes (varying number)
May see Barr bodies in female neutrophils (visible silenced X chromosome - lyonisation)
What are the 5 cardinal signs of inflammation?
Rubor, dolor, calor, tumor, loss of function
Redness, pain, heat, swelling
What are the stages of inflammation?m
- Increased vessel calibre - inflamm. cytokines - bradykinin, prostacyclin, NO. Mediate vasodilation
- Fluid exudate - vessel becomes leaky - fluid is forced out of vessel
- Cellular exudate - neutrophils become abundant in this exudate
What is neutrophils action in acute inflammation?
Margination - migrate to edge of BV
Adhesion - (selectins bind neutrophil, cause rolling along BV margin)
Emigration + diapedesis (movement out of BV - through or in between endothelium)
Chemotaxis -> site of inflammation
What occurs at the site of inflammation?
(Neutrophil action)
1. Phagocytosis
2. Phagolysosome + bacterial killing
3. Macrophages clear debris
What are the outcomes of acute inflammation?
Resolution (normal)
Supporation (purforration)
Organisation (granulation tissue + fibrosis) (cardiac tissue + neurons never resolve; most become this)
Progression (excessive recurrent inflammation -> becomes chronic + fibrotic tissue)
What are granulomas?
Aggregates of epitheloid histology (essentially macrophages)
From granulomatous ‘horseshoe’ shape
Central necrosis () -> classically TB
No central necrosis -> sacrolosis, leprosy, vasculitis (GCA,GPA,EGPA), crohns
Granuloma + eosinophil + parasite
Granulomas secrete ACE -> blood marker (increase in Pxw, granulomatous disease)
What are thrombi + emboli?
Thrombosis -> mass of blood constituents (mostly platelets) forming in vessels
- Vasospasm
- Primary platelet plug - vWF binds to exposed collagen and platelets bind to this (gp1b - activation -> discoid -> pseudopoid) - watch other - gp2a/3b - aggregation
- Coagulation cascade
What influences thrombosis?
Virchows triad
Endothelial injury
Decrease in blood flow
Hypercoagulability
What are the types of thrombosis?
Arterial- atherogenesis - other conditions etc
Venous - venous stasis - etc
What are the fates of thrombi?
Resolution - degrades, normal
Organisation - leaves scar tissue behind
Embolism - fragments of thrombi break off + log in distal circulation
What are emboli?
Thrombi fragments
Can be:
- arterial - lodges in systemic circulation (from left heart)
- venous - lodges in pulmonary circulation (from right heart)
Further conditions etc
What is atherosclerosis?
Plaques forming in intima + media of high pressure vessels (arteries)
What’s in a plaque?
Lipid, smooth muscle, macrophages (+foam cells) platelets, fibroblasts
What are foam cells?
Macrophages that phagocyte LDLs
What is the formation of atherosclerosis?
- Fatty streak - precursor to plaque ~ 10 years old
- Lipid accumulation - increase in LDL, macrophages recruited to phagocyte this; foam cells
- Platelet aggregation - plaque protrudes into artery lumen, disrupts laminar flow, so platelets accumulate here. Thinning of media occurs
- Fibrin mesh + RBC trapping - platelet plug forms fibrin mesh over itself (stable 2 clot) + RBCs trapped within this
- Fibrous cap - fibroblasts form smooth muscle cap over the 2 platelet plug -> this is a stable atheroma
What occurs in unstable Atheromas?
-> in unstable atheromas (angina -> ACS); fibrous cap damaged + continuous platelet plug formation over this, lumen narrowed
What occurs in unstable Atheromas?
-> in unstable atheromas (angina -> ACS); fibrous cap damaged + continuous platelet plug formation over this, lumen narrowed
What are risk factors for atherosclerosis?
DM, hypertension, smoking, obesity, increased age, male (all RF for MI!)
What is apoptosis?
Non-inflammatory controlled cell death
Cell shrink organelles retained + csm intact. Chromatin unaltered; fragmented for easy phagocytosis.
What are the mechanisms for apoptosis?
- Intrinsic
- Bax (protein inhibited by Bcl2) acts on mitochondrial membrane to promote cytochrome C release
- activates caspases -> apoptosis - Extrinsic
- Fas-L or TNF-L binds to csm receptors which activate caspases -> apoptosis - Cytotoxic
- CD8+ binding releases granzyme B from CD8+ cell; granzyme B -> perforin -> caspases -> apoptosis
What is necrosis?
Inflammatory traumatic cell death
- cells burst, organelles splurge, csm damaged, chromatin altered - cell is fd
Coagulation (mc, due to organ ischaemia), liquefaction (brain becomes soup), caseous (TB; soft cheese!), gangrene (black due to deposited FeS from Hb)