MoD 2 (Acute Inflammation) Flashcards
Define acute inflammation:
Accumulation of fluid exudate and neutrophils in tissues, controlled by chemical mediators from plasma/cells for protection
Name the 5 major causes of acute inflammation:
1) Microbial infections
2) Physical agents
3) Chemical agents
4) Tissue necrosis
5) Immune hypersensitivity reactions
Name the 5 characteristic signs of acute inflammation:
1) Redness ‘rubor’
2) Swelling ‘tumor’
3) Heat ‘calor’
4) Pain ‘dolor’
5) Loss-of-function
What are the 3 main tissue changes that occur in acute inflammation?
1) Vascular changes
2) Fluid exudation into tissues
3) Neutrophil immigration into tissues
How do vascular changes during acute inflammation lead to production of heat, swelling and redness?
Vasodilation of arterioles and capillaries = heat + redness
Increased membrane permeability and slowing of circulation = Swelling
What is a transudate?
A fluid with a low-protein content, which has passed through a membrane from a tissue/blood vessel etc.
What is an exudate?
A fluid with a high-protein content, which has escaped from a blood vessel into tissue
What is the main difference between a transudate and an exudate?
Transudate = low protein content Exudate = high protein content
What causes fluid to move from a blood vessel into tissue space (transudate)?
Increased hydrostatic pressure, usually due to decreased protein levels within blood
What causes exudate to move from a blood vessel into tissue space?
Usually inflammation
Name 2 mediators which cause endothelial cell contraction, leading to exudation of fluid into tissues:
1) Histamine
2) Leukotriene
Name 2 cytokines which cause cytoskeletal reorganisation, leading to exudation of fluid into tissues:
1) TNF
2) IL-1
What is the primary type of WBC in acute inflammation?
Neutrophil (Polymorphonuclear leucocyte)
What is the approx. life span of a neutrophil?
~ 12-20 hrs
A neutrophil nucleus is lobular. How many lobes is it made up of?
~ 2-5 lobes
Approx. how many granules does a neutrophil contain?
~ 2000 granules
Where are neutrophils usually found?
Bone marrow and blood
Inflamed tissue
How quickly do neutrophils travel?
~ 30 um/min
Name the 6 stages a neutrophil goes through to capture and kill bacteria:
1) Chemotaxis
2) Activation
3) Margination, Rolling, Adhesion
4) Diapedesis
5) Recognition-Attachment
6) Phagocytosis + Killing
Define chemotaxis:
Directional movement towards a chemical attractant
Name the powerful chemotaxin released by leucocytes:
Leukotriene B4
What must happen to a neutrophil before it can marginate and roll along the endothelium of a blood vessel?
Activation (becomes ‘sticky’)
How do neutrophils move across blood vessel walls?
Diapedesis: they produce collagenase which degrades the basement membrane, allowing cellular movement
When neutrophils ‘roll’ along the endothelium, what are they transiently binding to?
Selectins
Neutrophils roll along the endothelium by binding to Selectins. What is the name of the receptor which traps neutrophils?
Integrins
What enzyme do neutrophils secrete to break down the basement membrane surrounding a blood vessel wall?
Collagenase
Define opsonin:
Any molecule which enhances phagocytosis
Name the complement element which is a potent opsonin:
C3b
What are the 2 ways a neutrophil can kill a bacterium after phagocytosis?
1) O2 dependent (via free radicals)
2) O2 independent (via enzymes)
Name the enzyme contained within neutrophils which produces superoxide to kill bacteria:
NADPH oxidase
How can a neutrophil kill a bacteria using its O2 dependent pathway?
NADPH oxidase forms superoxide from O2,
Superoxide/Hydrogen peroxide/OH- releases via respiratory burst
Damages DNA/proteins/lipids
Which enzymes do neutrophils contain for O2-independent killing of bacteria?
Proteases
Phospholipases
Nucleases
Lysozymes
Which chemotaxin is expressed on the membrane of gram -ve bacteria?
Endotoxin
How does exudation and vasodilation help a tissue after injury?
- Dilutes toxins
- Maintains temperature
- Delivers nutrients/oxygen/cells/plasma proteins
How does pain and loss-of-function help a tissue after injury?
Enforces rest, allowing repair and preventing further damage
What is a vasoactive amine?
A substance which contains amino groups, and acts on blood vessels
Name 2 vasoactive amines:
1) Histamine
2) Serotonin
Which cells contain and release histamine?
Basophils
Mast cells
Platelets
Which cells contain and release serotonin?
Platelets
How does Histamine and Serotonin increase vascular permeability?
Stimulate contraction of endothelial cells, causing them to pull apart from each other
Both histamine and serotonin produce pain, arteriolar dilation and increased vascular permeability. What else does ONLY serotonin cause?
Stimulates fibroblasts
Name a vasoactive peptide which causes vasodilation:
- Bradykinin
- Morphine
- Parathyroid Hormone
- Substance P
- Vasoactive Intestinal Peptide
Name a vasoactive peptide which causes vasoconstriction:
- Vasopressin
- Thyrotropin-Releasing-Hormone
- Angiotensin II
- Prolactin
How is Bradykinin produced?
Kallikrein cleaves Kininogen into Bradykinin
What effect does Bradykinin have on the body?
- Pain
- Increases vascular permeability
- Vasodilation