Session 2 (1) - Acute inflammation Flashcards
Define acute inflammation
Response of living tissue to injury initiated to limit tissue damage
In general, what occurs in acute inflammation?
Vascular and cellular reactions controlled by a variety of chemical mediators derived from plasma or cells. Protective function, but can lead to complications and systemic effects
What are five causes of acute inflammation?
- Microbial infections e.g. pyogenic organisms
- Hypersensitivity reactions
- Physical agents e.g. heat and trauma
- Chemicals
- Tissue necrosis – elicits inflammatory reaction
What are the five macroscopic features of acute inflammation?
- Rubor – redness
- Tumor – swelling
- Calor – heat
- Dolor – pain
- Loss of sensation
What are the three main tissue changes in acute inflammation?
Changes in blood flow (vasodilation)
Exudation of fluid into tissues (oedema)
Infiltration of inflammatory cells
What are the four microscopic features of acute inflammation?
Oedema
Vasodilation
Neutrophil margination and migration
What is the purpose of oedema in acute inflammation?
Delivers plasma proteins to point of inflammation (immunoglobulin, inflammatory mediators, fibrinogen (localizes inflammation due to sticky nature)
Dilutes toxins
Increases lymphatic drainage (delivers MO’s to phagocytes and antigens)
What is the purpose of vasodilation in acute inflmamation?
Increases delivery of antibodies, nutrients, oxygen and cells AND increases temperature
What is the purpose of neutrophil margination and emigration in acute inflammation?
Removes pathogenic organismsand necrotic debris
What is rubor a result of?
Vasodilation
What is tumour a result of?
Oedema/infiltration of neutrophils
What is calor due to?
Vasodilation
What is dolor caused by and why is it useul?
Chemical mediators such as bradykinin involved in pain mechanism.
Dolor is useful as it enforces rest and reduces chance of further traumatic damage.
What causes loss of sensation in actute inflammation?
Neurologic response to pain
What is oedema?
Excess fluid in intersitium, can be transudate or exudate.
What is exudate oedema?
Fluid loss in inflammation, high in protein
What are three chemical mediators involved in oedema formation in acute inflammation?
Histamine (transient), bradykinin (maintains permeability) and leukotrienes
What is histamine produced by and why?
Mast cells, basophils and platelets, in response to
- physical damage
- immunologic reactions
- C3a, C5a and IL-1 factors from neutrophils and platelets
What does histamine do?
Causes vascular dilation, a transient increase in vascular permeability and pain
What response are histamines a part of?
The immediate early response