general pathology Flashcards
hospital autopsies
<10% of autopsies in the UK
Requires Medical Certificate cause of Death (MCCD)
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medico-legal autopsies
> 90% of autopsies in the UK
Coronial
forensic
presumed natural death
Cause of death not known
not seen by doctor within days of death
presumed iatrogenic deaths
peri/post operative deaths
anaesthetic deaths
abortion
complications of therapy
presumed unnatural deaths
accidents
custody deaths
war/industrial pensions
doctor referral for autopsy
No statutory duty to refer
common law duty
GMC guidance
registrar of BDM referral for autopsy
statutory duty to refer
other referrals for autopsy
Relatives
the police
anatomical pathology technicians
histopathologists
Hospital autopsies
coronial autopsies (Natural deaths, drowning, suicide, accidents, road traffic deaths, fire deaths, industrial deaths, peri/post operative deaths)
forensic pathologists
Coronial autopsies (homicide, death in custody, neglect and any done by histopathologists due to the action of a third party)
inflammation
local and physiological response to tissue injury
not a disease but a manifestation of disease
outcomes and harmful effects of inflammation
Benefits=
resolution
suppuration
organisation
Diseases= Digestion of normal tissue Swelling Compressing brain tissue Fibrosis from chronic inflammation Autoimmunity Over reaction to stimulus
acute inflammation
initial and often transient series of tissue reactions to injury
sudden onset
short duration
usually resolves
cell type= neutrophil polymorphs
chronic inflammation
Subsequent of often prolonged tissue reactions following the initial response
slow onset or sequel to acute
long duration
may never resolve
cell type= macrophages
cells involved in inflammation
neutrophil polymorphs macrophages lymphocytes endothelial cells fibroblasts
neutrophil polymorphs (inflammation)
short lived
first on the scene of acute
cytoplasmic granules full of enzymes that kill bacteria
usually die at the scene of inflammation
release chemicals that attract other inflammatory cells such as macrophages
macrophages (inflammation)
long lived cells- weeks to months
phagocytic properties
ingest bacteria and debris
carry debris away
present antigens to lymphocytes
lymphocytes (inflammation)
long lived cells- years
produce chemicals that attract other inflammatory cells
immunological memory
endothelial cells (inflammation)
line capillaries
become sticky in areas of inflammation so inflammatory cells adhere to them
become porous to allow inflammatory cells to pass into tissues
fibroblasts (inflammation)
long lived cells
form collagen in areas of chronic inflammation
causes of acute inflammation
microbial infections (bacterial, viruses)
hypersensitivity (parasites, allergic reactions)
physical agents (trauma, ionising radiation, heat)
chemicals (corrosives, acids, alkalis)
bacterial toxins
tissue necrosis
microbial infections (inflammation)
most common cause of acute inflammation
viruses lead to death of cells by intracellular multiplication
bacteria release exotoxins
parasitic infections and TB inflammation are examples of where hypersensitivity is important
hypersensitivity inflammation
altered state of immunological responsiveness causes inappropriate or excessive immune reaction
damages tissues
has cellular or chemical mediators
physical agents in inflammation
tissue damage leading to inflammation may occur through physical trauma, UV or other ionising radiation, burns or frostbite
chemicals in inflammation
corrosive chemicals provoke inflammation through gross tissue damage
infecting agents may release specific chemical irritants that lead directly to inflammation
tissue necrosis (inflammation)
death of tissues to due lack of oxygen or nutrients
usually from inadequate blood flow
acute inflammatory response due to peptides released from dead tissue
macroscopic appearance of inflammation
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Swelling, Heat, Red, Pain, Loss of function
Rubor
Redness
acutely inflamed tissue appears red
caused by dilation of small blood vessels in damaged area
Calor
Heat
only in peripheral parts of the body- skin
caused by increased blood flow- hyperaemia
vascular dilation to deliver blood to area
systemic fever from chemical mediators, contributes
tumor
Swelling
oedema- accumulation of fluid in extravascular space as part of fluid exudate
physical mass of inflammatory cells migrating into the area
formation of connective tissue
dolor
Pain
partly stretching of tissues due to oedema and pus under pressure in abscess cavity
chemical mediators- bradykinin and prostaglandins and serotonin- induce pain
loss of function
movement of inflamed area is consciously and reflexly inhibited by pain
severe swelling may immobilise tissues
Acute inflammation response has 3 processes
changes in vessel diameter and flow
increased vascular permeability and formation of the fluid exudate
formation of the cellular exudate- emigration of neutrophil polymorphs into extravascular space
stages in neutrophil polymorph emigration (inflammation)
margination of neutrophils
pavementing of neutrophils
pass between endothelial cells
pass through basal lamina and migrate into adventitia
endogenous chemical mediators cause:
inflammation
vasodilation
emigration of neutrophils
chemotaxis
increased vascular permeability
itching and pain
chemical mediators released from cells
inflammation
histamine
lysosomal compounds
chemokines
plasma factors
inflammation
enzymatic cascade systems, which are unrelated and produce various inflammatory mediators
systemic effects of inflammation
pyrexia
constitutional symptoms
weight loss
amyloidosis
causes of chronic inflammation
transplant rejection
progression from acute
primary chronic
recurrent episodes of acute
macroscopic appearance of chronic inflammation
chronic ulcer
chronic abscess cavity
thickening of the wall of a hollow viscus
granulomatous inflammation
fibrosis
microscopic features of chronic inflammation
The cellular infiltrate consists characteristically of lymphocytes plasma cells and
macrophages
A few eosinophil polymorphs may be present, but neutrophil polymorphs are scarce
Some of the macrophages may form multinucleate giant cells
There may be evidence of continuing destruction of tissue at the same time as tissue
regeneration and repair
Tissue necrosis may be a prominent feature, especially in granulomatous conditions such as tuberculosis
granulomas
aggregate of epitheliod histiocytes (activated macrophages)
may contain other cells such as lymphocytes and histiocytic giant cells
granulomatous inflammation is a specific type- such as tuberculosis and leprosy
epitheliod histiocytes
resemble epithelial cells
activated macrophages
arranged in clusters
little phagocytic activity but adapted to secretory function
appearance of granulomas
may be augmented by presence of caseous necrosis or by conversion of some of the histiocytes into multinucleate giant cells
histiocytic giant cells
form where particulate matter, that is indigestible by macrophages, accumulates
form when foreign particles are too large to be ingested by just one macrophage
multinucleate giant cells w/ 100+ nuclei
little phagocytic activity
types of histiocytic multinucleate cells
langhans giant cells- horse shoe arrangement of peripheral nuclei at one pole
foreign body giant cells- large with nuclei randomly scattered throughout
touton giant cells- central ring of nuclei, peripheral to which there is lipid material
treating inflammation
aspirin
ibuprofen- inhibit prostaglandin synthase
steroids- bind to DNA up regulate inhibitors of inflammation and down regulate chemical mediators of inflammation
regeneration/resolution
initiating factor is removed
tissue is undamaged or able to regenerate
examples of regeneration
liver after surgery to remove a lobe
lobar pneumonia- pneumocytes can regenerate
skin abrasions
skin wounds- healing by first intention
repair
initiating factor is still present
tissue is damaged and unable to regenerate
replacement of damaged tissue by fibrous tissue
collagen produced by fibroblasts
brain fibrosis= gliosis
examples of repair
heart after myocardial infarction
brain after cerebral infarction
liver cirrhosis
skin wounds- healing by second intention
cells that regenerate
hepatocytes pneumocytes blood cells gut epithelium skin epithelium osteocytes
cells that dont regenerate
myocardial cells
neurones
regeneration example
healing by first intention-
sutured edge to edge two edges fill gap with blood and fibrin epidermis regrows fibroblasts form collagen scar forms, stronger than normal skin
repair example
healing by seconds intention
large amount of tissue loss- normally trauma
can’t be sutured together
gap present so no epithelial cells to regenerate
gap filled by capillaries and collaged until two edges can grow
large scar formed
Ways our healthy body prevents thrombosis occurring spontaneously
Laminar flow- cells travel in the centre of arterial vessels and don’t touch the side
endothelial are not sticky when they are healthy
thrombosis definition
the formation of a solid mass from blood constituents in an intact vessel of a living person
formation of a thrombus
platelet aggregation
platelets release chemicals when they aggregate causing them to start the cascade of clotting proteins in the blood
both of these reactions involve positive feedback loops; therefore difficult to stop
once clotting cascade has started there is a formation of insoluble fibrin
causes of thrombosis
change in vessel wall
change in blood flow
change in blood constituents
usually a combination of two or three
drugs preventing thrombosis
aspirin
heparin
warfarin
embolus definition
mass of material in the vascular system able to become lodged within a vessel and block it
formed when a solid mass in the blood is carried through the circulatory system to a place where it gets stuck and blocks it
cause of embolism
thrombus
air
other- cholesterol crystals, tumours, amniotic fluid, fat
embolism location
in venous system then- vena cava -> right side of heart -> lodge in pulmonary arteries (location depends on size) -> can lodge as lungs split into capillaries (lungs act as a filter for venous emboli
in arterial system it can travel anywhere downstream
ischaemia
reduction in blood blow to a tissue without any other implications
inadequate blood supply
infarction
reduction in blood flow to a tissue with subsequent local cell death
macroscopic event usually caused by thrombus blockage
atheroma
aka atherosclerosis
pathology of arteries when there is deposition of lipids in the arterial wall with surrounding fibrosis and chronic inflammation
the plaques can enlarge to occlude the lumen of vessels
endothelium overlying a plaque may rupture and initiate thrombosis within the vessel
plaques are predominant cause of myocardial or cerebral infarction