Acute Inflammation Flashcards
List a few causes for acute inflammation
Microbial infections, hypersensitivity reactions, physical agents, chemicals and tissue necrosis. NB: reaction to all of these agents looks the same
What is acute inflammation?
Response of living tissues to injury. Its initiated to limit tissue damage and has a short duration
What are the five clinical features of acute inflammation?
Rubor (redness), tumour (swelling), calor (heat), dolor (pain) and loss of function
What are the main changes in tissues due to acute inflammation?
Vascular changes (changes in blood flow and exudation of fluid) and cellular changes (infiltration of inflammatory cells)
What changes in blood flow occur during acute inflammation?
Transient vasoconstriction –> vasodilation –> increase blood flow –> increased permeability of BV –> swelling –> increased viscosity leading to stasis –> release of histamine from mast cells, basophils and platelets
What is starlings law?
Increased hydrostatic pressure leads to increased fluid flow out of the vessel. Decreased colloid osmotic pressure leads to increased flow of fluid out of the vessel
What is exudate?
How does it differ from transudate?
Exudate is a fluid with a high content of protein and cellular debris which has escaped from the blood vessels and been deposited in tissues.
Transudate has a low protein content, high fluidity and low content of cells or solid materials
List the mechanisms of vascular leakage
Endothelial contraction Cytoskeletal reorganisation Direct injury Leukocyte dependent injury Increased transcytosis
What is the role of fibrin in acute inflammation?
Prevents blood leaking out of vessels because it is sticky, thus localising the inflammatory response
What is the primary type of white blood cell involved in acute inflammation?
Neutrophil leukocytes
Describe the process of infiltration by neutrophils
Margination - stasis causes neutrophils to line up at the edge of BV along the endothelium
Rolling - neutrophils roll along endothelium, sticking to it intermittently
Adhesion - neutrophils stick more avidly
Emigration of neutrophils through BV walls
How do neutrophils leave blood vessels?
Relaxation of inter-endothelial cell junctions.
Localised digestion of vascular basement membrane.
Movement from inside the cell to outside the cell.
How do neutrophils move?
Chemotaxis (e.g. C5a), receptor-ligand binding, rearrangement of cytoskeleton, production of pseudopod, bacterial peptides
What are the functions of neutrophils?
Contact, recognition and internalisation. Cytoskeletal changes. Phagosomes fuse with lysosomes to produce secondary lysosomes
Why does inflammation cause pain?
Chemicals that stimulate nerve endings are released, making the nerves much more sensitive.
How do anti-inflammatories work?
They block the effects of enzymes which play a key role in making prostaglandins (e.g. Cox-1 and Cox-2 enzymes).Thus production of prostaglandins is inhibited, resulting in reduced swelling and reduced pain.