Inflammation Flashcards
avascular tissue
cartilage or cornea
five cardinal signs of inflammation
redness, swelling, heat, pain/tenderness, loss of function
stresses that can cause inflammation
- Genetic mutations
- Hypoxia (lack of oxygen)
- Infection
- Physical agents (pressure and trauma)
- Immune reactions eg. hypersensitivities and autoimmunity
outcomes of mild transient injury
reversible, cell can recover and return to homeostasis as long as cell membranes remain intact eg. steatosis in liver
apoptosis general mechanism
- Membrane blebs (bubbles form)
- Chromatin condenses
- Blebs bud off to break cell up into apoptotic bodies
- Fragments digested by phagocyte
apoptosis energy dependant?
yes
Intrinsic (mitochondrial pathway) of apoptosis
removal of growth factors/hormones leads to cascade through mitochondrion, eventually producing caspases (protease enzymes) that disintegrate DNA and cytoskeleton to cause blebbing
Extrinsic (death receptor mediated) pathway of apoptosis
Fas death ligand binds to surface receptor to initiate protein cascade that produces caspases
when is apoptosis used?
in physiological development and homeostasis: if cells ordinarily divide, old ones may need to be destroyed
necrosis energy
passive process
general necrosis mechanism
Membrane blebs but then breaks down Cell bursts (lysis) and spills contents → mass inflammation Activated by toxins released/macrophages
types of necrosis
coagulative, liquefactive, caseous, gangrenous, fat
coagulative necrosis
nuclei stain darker and ‘jelly’ appearance as proteins denature eg. ischaemia in heart attack
Liquefactive necrosis
protein digested in lipid rich tissue so tissue structure lost; pus eg. stroke in brain
caseous necrosis
‘cheese’ appearance of granulomatous inflammation eg. tuberculosis
gangreous (dry) necrosis
coagulative necrosis in extremity due to slow vascular blockage eg. toe gangrene in diabetes. Wet gangrene= infection
fat necrosis
chalky deposits from degraded fat tissue eg. acute pancreatitis
types of inflammation
- Acute inflammation
- Chronic inflammation
- Subacute inflammation- inflammatory response that isn’t a rapid, immediate response to a new injury
- Acute on chronic inflammation- where a chronic condition rapidly worsen
- Fulminant inflammation- severe, acute inflammation with chronic damage that has become irremediable
what diseases can inflammation cause or worsen?
cancers, atherosclerosis, neurodegenerative disease
exudate
Delivered cells, proteins, fluid
types of danger signals
- Missing self-recognition- activation of NK cells and the complement system when certain signals usually present on host cells are absent
- Effector-triggered immunity (system surveillance)- detects disturbances in cellular processes (like ion fluctuations due to bacterial pore forming proteins)
- Structural pattern-triggered immunity- molecular patterns that indicate danger that are picked up by the immune system
DAMPs
damage associated, molecules that trigger the inflammatory response when cells are damaged- these include DNA, RNA and histones
PAMPs
pathogen associated, molecules on the surface of microbes trigger inflammation when infection occurs- can be foreign wall cell components (like lipopolysaccharide) or nucleic acid
how are danger signals recognised?
‘sentinel’ leukocytes that surveillance body- can be resident in tissues or circulaiting in tissue, have pattern recognition receptors (PRRs) which allow the release of cytokines that activated inflammatory response
examples of surface PPRs
C-type lectin receptors, TLRs (toll like receptors)
Examples of cytoplasmic PPRs:
endosomal TLRs and nod like receptors
effects of PPR activation
- Activation of pro-inflammatory cytokines eg. IL-1, IL-6, TNF-α
- Programmed lytic death
- Inflammatory mediators: histamine, prostaglandins, leukotrienes, bradykinin, cytokines and chemokines
cytokines
activate resident, endothelial or circulating immune cells to maintain vasodilation and cause lysis in infected cells so that the pathogen is exposed to the immune system
opsonins
mark out cells for phagocytosis, phagocytosis may be oxygen deprived or oxygen-independent