PATHOLOGY- Essentials of general pathology - Review of inflammation and repair Flashcards
What is inflammation
Response of vascularised tissue to injury
What is the purpose of inflammation
- Get necessary components to site of injury
- To isolate / contain injury
- To destroy microbes / inactivate toxins
- To remove debris / prepare injury site for & intitiate repair
Inflammation is critical for what
Normal tissue maintenance
When can inflammation be harmful
Poorly controlled/regulated
Mis-detected -> harmless allergens, self-antigens
Stimulus persistent/ unable to irradicate
What are the 2 forms of inflammation
Acute
Chronic
Definition of acute inflammation
Rapid host response that delivers leukocytes and plasma proteins (e.g. antibodies / fibrinogen) to sites of infection or tissue injury e.g. necrosis
Characteristics of chronic inflammation
Later onset
Longer duration
Lymphocytes/macrophages predominate
What does acute inflammation result from
Infection
Necrosis
Immune reactions
FBs
Characteristics of acute inflammation
Early onset
Short duration
Oedema
Neutrophils predominate
2 components in acute inflammation
Vascular reactions
Cellular reactions
Major features of acute inflammation
- Changes in vascular flow / vessel calibre (RUBOR / CALOR)
- Increased vascular permeability (vascular leakage) -> fluid exudate (TUMOR)
- Recruitment of leukocytes to site of injury / infection -> cellular exudate (DOLOR)
What effect do the vascular changes have in acute inflammation.
Vascular changes maximise the movement of plasma proteins and inflammatory cells from the circulation in to the site of injury
List the vascular changes that occur in acute inflammation
- VASODILATION
- Initial brief vasoconstriction
- ^Blood flow -> erythema (rubor) - ^ VASCULAR PERMEABILITY
- Retraction of endothelial cells
- Endothelial injury
- Leukocyte mediated vascular injury
What is the result of the vascular changes that occur in acute inflammation
Escape of protein rich fluid (exudate) into extra vascular tissues -> fluid exudate -> oedema
Proteins in the fluid exudate as a result of vascular changes in AI include what
Immunoglobulins and coagulation factors (including fibrinogen)
What effect does an increase in fluid/protein loss lead to
Increased viscosity of the blood/rbc concentration
This decreases blood flow
Allows stasis to occur
What is the role of stasis
Stasis facilitates leukocyte accumulation on vessel wall -> “extravasation”
List the cellular changes that occur in acute inflammation
- Extravasation/emigration
- movement of leukocytes from vessels to the site of injury
- mainly neutrophils
What are the 5 steps in extravasation
- Margination
- Rolling
- Adhesion
- Migration (diapedesis)
- Chemotaxis
What is margination, rolling and adhesion mediated by
CAMs (Cellular adhesion molecules)
Where are CAMs expressed
Endothelium or leukocytes
What happens in margination
Vascular stasis causes neutrophils to move out from central axis towards vessel wall
What happens in rolling
- Cytokines (e.g. TF/IL-1) from damaged tissue -> activate endothelial CAMS
- Neutrophil surface ligands interact with endothelial selectins -> ‘slowly roll’
What happens in adhesion
High affinity integrins on neutrophils bind to integrin ligands on endothelium -> stop neutrophil on vessel wall
What happens in migration (diapedesis)
- Neutrophils move through intracellular junctions medicated by PCAM-1 / CD31
Characteristics of chronic inflammation
Later onset
Longer duration
Lymphocytes/macrophages predominate