Pathology 2 Flashcards
Define Acute Inflammation
Initial, transient series of tissue reactions to injury
Lasts hours to days
Example of acute inflammation
Appendicitis
State 2 benefits of inflammation
Destroys invading microorganisms
Walls off abscess cavity ∴ prevents spread of infection
State 2 disadvantages of inflammation
Fibrosis can distort tissue and alter function
Abscess (e.g. in brain) can act as space-occupying lesion ∴ compressing surrounding structures
List some examples of acute inflammation
Microbial infections (e.g. bacteria, viruses)
Hypersensitivity reactions (e.g. parasites)
Physical agents (e.g. trauma)
Chemicals (e.g. corrosives)
Bacterial toxins
Tissue necrosis (e.g. ischaemic infarction)
Describe the steps of acute inflammation
- Vascular changes - vasodilation! ∴ ↑ vessel flow
- ↑ Vessel permeability ∴ formation of fluid exudate
- Formation of cellular exudate - neutrophil polymorphs emigrate into extravascular space
What are the potential outcomes of acute inflammation?
- Resolution
- Suppuration - pus formation
- Organisation - healing via fibrosis
- Progression to chronic inflammation
5 Cardinal signs of inflammation
- Rubor (redness)
- Calor (heat)
- Tumor (swelling)
- Dolor (pain)
- Functio laesa (loss of function)
Rubor is due to
dilation of capillaries within damaged area
Calor is due to
Increased blood flow to damaged region
Results in vascular dilation
∴ more warm blood to region
Also, maybe systemic fever
Tumor is due to
Oedema!
(fluid accumulates in extravascular space)
+ formation of new connective tissue
Also, maybe mass of inflammatory cells migrating into region
Dolor is due to
Stretching of tissue due to inflammatory odema
+ pus under pressure in abscess cavity
Also, chemical mediators of acute inflammation are known to cause pain
e.g. bradykinin, prostaglandins, serotonin
Functio laesa (loss of function) due to
Conscious and reflexly inhibited by pain
+ severe swelling may immobilise tissue
What cellular component is essential for a histological diagnosis of acute inflammation?
ACCUMULATION of neutrophil polymorphs
How does organisation (healing by fibrosis) work in acute inflammation?
Dead tissue and inflammatory exudate first removed from damaged areas BY MACROPHAGES
Defect is then filled by specialised vascular connective tissue (aka GRANULATION TISSUE) - this is organisation
Then granulation tissue gradually produces collagen to form fibrous scar
How do microbial infections cause acute inflammation?
VIRUSES - cause death of cells via intracellular multiplication
BACTERIA - release specific eXotoxins, these make chemicals that initiate inflammation
+ release specific enDotoxins, associated w cell walls
How do hypersensitivity reactions cause acute inflammation?
Altered immunological response cause inappropriate/excess immune response - damages tissues
Cellular or chemical mediators
How do physical agents cause acute inflammation?
Tissue damage through -
e.g. physical trauma, burns,, radiation (UV), frostbite
How do irritant and corrosive chemicals cause acute inflammation?
Gross tissue damage (from acids, alkalis etc)
Infecting agents may release specific chemical irritants that cause inflammation directly
How does tissue necrosis result in acute inflammation?
Tissue death from lack of O2/nutrients
∴ infarction
^ potential inflammatory stimulus due to peptides released from dead tissue
What accumulates in the extracellular space of damaged tissue in the early stages of acute inflammation?
Oedema fluid
Fibrin
Neutrophil polymorphs
Smooth muscle of arteriolar walls form __________ to regulate blood flow through the capillary bed
Pre-capillary sphincters
What happens to the pre-capillary sphincters in arteriolar walls in acute inflammation?
Relax
∴ ↑ Blood flow through capillaries
How is capillary hydrostatic pressure and therefore, osmosis into the extravascular space changed during acute inflammation?
What happens to the vascular permeability?
Pressure increased
∴ increasing osmotic pressure
∴ more fluid leaving vessels than returned
∴ ↑ Vascular permeability