Session 2: Acute Inflammation Flashcards
When and why does acute inflammation occur?
- Response of living tissue to injury
- Initiated to limit the tissue damage
What are some characteristics of acute inflammation? (4)
- innate
- immediate
- stereotyped
- Short duration - mins/hrs/few days
What tissue changes are brought about by acute inflammation? (3)
- Vascular flow
- Formation of a fluid exudate
- Neutrophil emigration
What are the causes of acute inflammation? (5)
- Microbial infections
- Acute phase hypersensitivity reactions
- Physical agents
- Chemicals
- Tissue necrosis
What are the characteristic clinical signs of acute inflammation? (5)
- Rubor
- Tumour
- Calor
- Dolor
- Loss of function
What are the 3 stages of the vascular phase of acute inflammation?
- Changes in blood flow
- Exudation of fluid into tissues
- Infiltration of inflammatory cells
What changes to blood flow occur in the vascular phase? (4)
- Initial few secs vasoconstriction of arterioles
- Vasodilation of arterioles and then capillaries
- Increased permeability of blood vessels
- Stasis - Concentration of RBCs in small vessels and increased viscosity of blood
What is the effect of increased permeability of blood vessels? (2)
- Exudation of protein-rich fluid into interstitium
2. Slowing of circulation (swelling)
Which chemical mediator in vessels is involved in the immediate early response?
Histamine
Which cells release histamine? (3)
Mast cells
Basophils
Platelets
What stimulates the release of histamine? (5)
- Physical damage
- Immunologic reaction
- Complement factors C3a and C5a
- IL-1
- Factors from neutrophils and platelets
What effects does histamine bring about? (3)
- Vascular dilatation
- Transient increase in vascular permeability
- Pain
What chemical mediators are involved in the persistent response? (Incompletely understood) (2)
Leukotrienes
Bradykinin
What determines fluid loss from vessels? (2)
- Increased hydrostatic pressure
2. Increased colloid osmotic pressure of interstitium
What causes an increase in hydrostatic pressure resulting in fluid exudation?
Arteriolar dilatation
What are the consequences of vascular leakage?
Oedema
What are the 2 types of fluid that could accumulate in the interstitium in oedema?
Transudate or exudate
What is transudate?
What is exudate?
Transudate - low protein content (fluid loss due to hydrostatic pressure imbalance only)
Exudate - more protein content than plasma (inflammation)
How can fluid extracted from pleural effusion help in diagnosis?
High protein content (exudate) - inflammation
Low protein content - heart failure or venous outflow obstruction
What are the mechanisms of vascular leakage? (5)
- Endothelial contraction - gaps
- Cytoskeletal reorganisation - gaps
- Direct injury of vessel walls - toxic burns, chemicals
- Leukocyte-dependent injury
- Increased transcytosis - channels across endothelial cytoplasm
Which chemical mediators are involved in endothelial contraction?
Histamine
Leukotrienes
Which chemical mediators are involved in cytoskeletal reorganisation?
Cytokines
- IL-1
- TNF
How do leukocytes trigger leukocyte-dependent injury?
Toxic oxygen species and enzymes released
Which signal protein is responsible for transcytosis?
VEGF - vascular endothelial growth factor
