Basic Pathology Flashcards
(203 cards)
Define inflammation
The local physiological response to to tissue injury, it is not itself a disease but a manifestation of disease
What beneficial effects might inflammation have?
Destruction of invading organisms and the walling off of an abscess cavity to prevent spread of infection
What harmful effects might inflammation have?
May produce disease e.g. abscess in the brain would act as a space occupying lesion; compressing vital surrounding structures
Define acute inflammation
the initial and often transient series of tissue reactions to injury
Define chronic inflammation
the subsequent and often prolonged tissue reactions following the initial response
How else can inflammation be categorised?
By differences in cell type involved
Outline the steps of acute inflammation
- Initial reaction of tissue to injury
- Vascular component: dilation of vessels
- Exudative component: vascular leakage of protein rich fluid
- Neutrophil polymorph is the characteristic cell recruited to the tissue
- Outcome may be resolution, suppuration (abscess), organisation, or progression to chronic inflammation
List some causes of inflammation
Microbial infections, hypersensitivity reactions, physical agents, chemicals, bacterial toxins, tissue necrosis
How might a bacteria cause inflammation?
Release specific exotoxins- chemicals synthesised by them that specifically initiate inflammation- or endotoxins, which are associated with their cells walls
When do hypersensitivity reactions occur?
When an altered state of immunological responsiveness causes an inappropriate or excessive immune reaction that damages the tissues
What are the macroscopic appearances of inflammation?
- Redness (Rubor)
- Heat (Calor)
- Swelling (Tumor)
- Pain (Dolor)
- (loss of function)
Why does redness occur in inflammation?
dilation of small blood vessels within the damaged area
Why does heat occur in inflammation?
(only in skin) due to increased blood flow (hyperaemia) through the region, resulting in vascular dilation and delivery of warm blood to the area
Why does swelling occur in inflammation?
- Swelling results from oedema- the accumulation of fluid in the extravascular space as part of the fluid exudate
- to a much lesser extent, the physical mass of cells migrating to the area
- as the inflammation process progresses, formation of new connective tissue also contributes to swelling
Outline why pain occurs in inflammation
- Stretching and distortion of tissue due to inflammatory oedema and pus under pressure in an abscess cavity
- Some chemical mediators of acute inflammation e.g. bradykinin, prostaglandins and serotonin, are known to induce pain
Why does loss of function occur in inflammation?
Movement is consciously and reflexively inhibited by pain, while severe swelling may physically immobilise the tissue
What is essential for the histological diagnosis of acute inflammation?
presence of neutrophil polymorphs
Name the 3 processes involved in acute inflammation
- Change in vessel calibre and, consequently, flow
- Increased vascular permeability and formation of the fluid exudate
- Formation of the cellular exudate- emigration of the neutrophil polymorphs into the extravascular space
List the time course mechanisms of increased vascular permeability
- Immediate transient chemical mediators
- Immediate sustained severe direct vascular injury
- Delayed prolonged endothelial cell injury
Give some examples of immediate transient chemical mediators that increase vascular permeability
histamine, bradykinin, nitric oxide, C5a, leucotriene B4, platelet activating factor
Give an example of immediate sustained severe direct vascular injury
trauma
Give examples of delayed prolonged endothelial cell injury
X-rays, bacterial toxins
List the stages in neutrophil polymorph emigration
- Margination of neutrophils
- Pavementing of neutrophils
- Pass between endothelial cells
- Pass through basal lamina and migrate into adventitia
What do endogenous chemical mediators cause?
- Vasodilation
- Emigration of neutrophils
- Chemotaxis
- Increased vascular permeability
- Itching and pain