Flashcards in MOD S3 Deck (36)
What is acute inflammation?
The response of living tissue to injury, initiated to limit tissue damage
What are some causes of acute inflammation?
Hypersensitivity reactions (aka allergies)
What are the macroscopic signs of inflammation?
Calor - heat
Rubor - redness
Tumor - swelling
Dolor - pain
+ loss of function
What are the microscopic features of acute inflammation?
Gaps form in endothelium
Margination and emigration
Macrophages and lymphocytes
Describe the changes in blood flow in acute inflammation
Transient vasoconstriction of arterioles (a few secs)
Vasodilation of arterioles and then capillaries
Increased blood vessel permeability
Stasis- increased concentration of RBCs in small vessels and blood viscosity
What are some chemical mediators of vasodilation?
-Released ~30 mins into acute inflammation
-Released by mast cells, basophils and platelets
>Transient increase in vascular permeability
What are some chemical mediators of increased vascular permeability?
What determines fluid flow across blood vessel walls?
The balance of hydrostatic and colloid osmotic pressure
An increase in either will increase fluid movement out of blood vessel
What is a build up of tissue fluid called?
What does oedema lead to?
Increased lymphatic drainage
What is a transudate?
Fluid loss from blood vessels due to hydrostatic pressure only
Has a low protein content
Caused by cardiac failure or venous outflow obstruction
What is exudate?
Fluid loss from blood vessels
Seen in inflammation
Has a high protein content
What are some chemical mediators of leukocyte emigration?
What is another name for a neutrophil?
What do neutrophils do?
Move to the site of cell injury by chemotaxis
Phagocytose microorganisms by making contact, recognising and internalising them
Phagosomes then fuse with lysosomes to destroy contents
Activated neutrophils may release toxic metabolites and enzymes with damage host tissue
What is the difference between transudate and exudate?
Transudate has a low protein content
Exudate has a high protein content
What are some signs of the acute phase response of inflammation?
Altered sleep patterns
Changes in plasma concentrations of acute phase proteins eg CRP, Fibrinogen and α1-anti trypsin
What causes fever?
Production of endogenous pyrogens eg IL-1 TNFα and prostoglandin
What is leukocytosis
The process by which white blood cell production is accelerated
By IL-1, TNFα
Colony simulating factors released by macrophages and t-lymphocytes
What are the possible end results of acute inflammation?
Continued acute inflammation and chronic inflammation (eg abscess)
Chronic inflammation with fibrous repair
How may the mediators of acute inflammation be inactivated?
(Most have short half lives so degrade normally anyway)
Name the stages of neutrophil invasion in acute inflammation
Describe margination (in acute inflammation)
Stasis causes neutrophils to line up along the edges of blood vessels
Describe rolling (in acute inflammation)
Neutrophils roll along endothelium, intermittently sticking to it
Describe adhesion (in acute inflammation)
The neutrophils stick more firmly to the endothelial walls of blood vessels
Describe emigration (in acute inflammation)
Neutrophils move through blood vessel walls into tissues
When is complete resolution impossible?
When cell architecture of damaged cells is destroyed
How is complete resolution achieved?
All the changes of acute inflammation reverse
Mediators are inactivated
Neutrophils present die
Exudate drains via lymphatics
Fibrin is degraded by plasmin ect
Vascular changes stop:
>Neutrophils no longer marginate
>Vessel calibre and permeability returns to normal