Acute Inflammation Flashcards
Define Acute inflammation
Response of living tissue to damage. Usually innate, immediate and short duration e.g. minutes/hours/days
List 5 causes of acute inflammation
Microbial infection Hypersensitivity reaction Physical agents Chemicals Tissue necrosis
What are the 5 features of acute inflammation?
R-rubor- redness T-tumor- swelling C-calor- heat D-dolor- pain \+ Loss of function
What causes the main changes in tissue during A.I?
Changes in blood flow
Exudation of fluid into tissues
Infiltration of inflammatory cells.
How does blood flow change?
Transient vasoconstriction of arterioles
Vasodilatation of arteroiles to increase blood flow
Increased permeability of the vessels
Exudation of protein rish fluid into the tissue
Slowing of circulation - oedema
STASIS- increased viscosity of blood and conc of RBC in vessels
What is the role of histamine?
Is released from mast cells in response to stimuli.
e.g. physical damage, immuological response, factors released from neutrophils and platelets.
It causes: vascular dilatation, increase in vascular permeability, pain.
What is Starlings law?
Fluid flowing across capillary walls is determined by balance of hydrostatic and colloid osmotic pressure.
Comparing plasma an interstitial fluid.
What happens when you increase hydrostatic pressure?
Increased fluid out of the vessel
What happens when you increase the colloid osmotic pressure of interstitium?
increase fluid flow out of the vessel
Why does oedema occur?
Arteroilar dilatation leads to increase hydrostatic pressure
Increased permeability of vessel walls leads to loss of proteins into interstium.
Results in net flow of fluid out of the vessel into interstitial fluid.
What is the difference between transudate and exudate?
Exudate is high protein content- seen in inflammation
Transudate is low protein content. Due to low hydrostatic pressure- e.g. cardiac failure or venous outflow obstruction.
Explain the role of neutrophils
Granulocyte WBCs that are polymorphs.
they line up at the edge of the endothelium - Margination.
They then roll along and stick to the endothelium - Adhesion
Finally Emigration though the blood vessel wall
MR.AE
How do neutrophils escape from vessels?
Relaxation of interepithelial junctions
Digestion of vascular basement membrane
Chemotaxsis- movement along the concentration gradient of chemoattractants
What is diapedesis?
passage of blod cells through the endothelium
How do neutrophils kill?
O2 dependent- produces superoxide and hydrogen peroxide
O2 independent- lysozyme and hydrolases, BPI- bacterial permeability increasing protein.
c5a, LTB4, C3b
