Pathology Flashcards
what can inflammation be caused by?
injury, infection, trauma, foreign bodies, immune reaction, necrosis
what are the responses to injury?
vascular change, cellular change, chemical mediators, morphological patters
what happens during vascular change?
change in flow and vessel caliber, vasodilation, blood flow slows, arterioles then capillary beds, mediated by histamine and nitric oxide, white cell margination - rolling - pavementing - migrating, increased calor and rubor, cell adhesion molecules expressed on white and endothelial cells mediate pavementing
what are some cellular changes?
stasis, white cell margination (cells drift out), rolling, adhesion, migration
what are some adhesion molecules?
integrins (over 30 types, bind to ICAM), selectins (expressed on various cells), VCAM (vascular cell adhesion molecule), ICAM (intercellular adhesion molecule)
what is the intergrin/selectin interaction with their ligand like?
of low affinity and binding on is fast as well as binding off
what are the inflammatory cells?
histamine and thrombin from inflammatory cells increase selectin expression, tumour necrosis factor (TNFY and interleukin-1 (IL-1) increase endothelial cell expression of VCAM and ICAM
what is avidity?
the strength of the total binding
what happens during increased avidity?
chemokine from the site of the injury bind to proteoglycans on endothelial cell surfaces, these proteoglycans then increase the affinity of VCAMs and ICAMs for integrins
what happens due to vascular permeability?
leaky vessels - loss of proteins, change in osmotic pressure, water flows protein - swelling (tumour)
why are the vessels so leaky?
endothelial contraction - histamine, bradykinin substance P, leukotrienes, if its direct injury, toxins and burns. VEGF makes new vessels but also increase leakiness
what is chemotaxis?
when cells follow a chemical gradient and move along it , bacterial components, complement to help find the injury, leukotrienes, cytokines (interleukins)
what are the three stages of phagocytosis?
recognition and attachment, engulfment, killing and degradation
what happens during recognition and attachment?
mannose receptors, bacterial surface glycoproteins and glycolipids contain terminator mannose residues, scavenger receptors, similar to mechanism that phagocytes recognise low density lipoprotein, opsonins (peptides that attach to antigens) include components of the complement cascade as well as IgG
what happens during engulfment?
pseudopods, vesicle formation (phagosome) joins with lysosome (phagolysosome)
what happens during killing and degradation?
reactive oxygen species (ROS), NADPH oxidase (oxygen gains an electron from NAGPH and become superoxide), reactive nitrogen species, nitric oxide synthase (combines NO with superoxide and produces ONOO) many other cytotoxic granules
what does rubor mean?
redness - increased perfusion, slow flow, increased permeability of vessels
what does calor mean?
heat, increased perfusion, slow flow rate, increased vascular permeability
what does tumour mean?
swelling, due to vascular changes
what does dolar mean?
pain, mediated by prostaglandins and bradykinin
what does function lease?
loss of function
what’s the microscopic appearance of an acute infection?
the cell that characterises acute inflammation is the neutrophil, polymorph, many lobes to the nucleus, granulocyte, phagocytic and cytotoxic abilities
how long to neutrophils survive for?
only a couple of hours one outside of the blood vessel
what does inflammation repair depend on?
site if injury, type of injury and duration of injury (can it be removed)
what does resolution mean?
complete restoration of the tissue to normal after removal of inflammatory components , minimal cell death, tissue has capacity to repair. good vascular supply, injurious agent easily removed
what is suppuration?
formation of pus (pis contains living, dying and dead cells, neutrophils, bacteria, inflammatory debris), may be termed abscess, when a space is filled by puss and walled off it may be called empyema
what is organisation and repair?
essentially scarring, the the injury produces lots of necrosis, and lots of fibrin that isn’t easily cleared, poor blood supply and tissue type. mucosa where damage goes beyond the basement membrane favours healing by organisation and repair
what do erosions and abrasions describe?
injury with basement membrane intact, heal rapidly with complete resolution
what is a common healing response in all tissues?
granulation tissue formation:
defect is slowly infiltrated by capillaries and then by myofibroblasts, deposit collagen and smooth muscle cells, given constituents it looks very red
how does the liver heal after infection?
has some regenerative capacity, undergoes scarring and fibrosis, known as cirrhosis in the liver, results in liver failure, can’t remove toxins and can’t make proteins, large volume of blood flows through liver - vascular disturbance
what happens during chronic inflammation?
favoured if: suppuration, walled off pus and scarring, persistence of injury, infectious agents and if the injury is autoimmune or a transplant rejection, characterised by lymphocytes and macrocytes/monocyte
what are macrophages?
they are specific immune cells, granulomas, aggregate of epithelioid histiocytes
what are the TB granulomas?
caseous necrosis
what are granulomas?
a structure formed during infection found in many diseases, a collection of immune cells (macrophages)
what is a myocardial infarction?
a heart attack
what is a hypoxic injury to the heart?
no oxygen resulting in no ATP resulting in cell injury and acute inflammation
what happens in there is no ATP?
Na/K ATPase fails, increased K, giving swelling, calcium pump fails, increased intracellular calcium which stimulates:
ATPase, phospholipase, proteases, endonuclease, mitochondrial permeability
what happens during a heat attack after the first 20 minutes?
cell death, die via apoptosis or necrosis, cells shrink and become red, nucleus shrinks and becomes darker and marginal contraction band appears
what happens during the first 24 hours of a heart attack?
cell contents leaked, compliment cascade initiated, acute inflammation, necrosis and neutrophils may be all that is holding it together - risk of cardiac rupture, soon neutrophils fade and are replaced by macrophages
what happens after necrosis?
the cells are dead and neutrophils mop them up
what are the three types of necrosis?
caseous (TB), liquefactive, coagulative - cell death with some structure of cells left as ghost outline before complete phagocytosis of material
is resolution likely after necrosis of the heart?
no more likely restitution which is a gradual process, progressive scarring macrophages fade away and are replaced by fibroblasts
what do fibroblasts do?
gradually lay down collagen complete after 6 weeks