Allergy $ Circulation Flashcards
Outline myogenic flow autoregulation
degree of stretch of arteriolar muscle triggers vasoconstriction/dilation
What is the Basophil Activation Test (BAT) used for?
Measure the effects of subcutaneous immunotherapy
Outline 3 mechanisms that can decrease venous capacity
Skeletal muscle pump
Respiratory pump
Changes in venomotor tone
Define allergy
hypersensitivity reaction produced by immunological response
Outline the mechanism of tolerance induction by IT?
Blocking antibodies - serum allergen specific IgG / IgA
Alteration of T cell response - decreased allergen stimulated T cell proliferation
- increase regulatory T cells which produce immune tolerant cytokines
Outline 2 humoural response systems that change blood vessel diameter
RAAS response - angiotensin II
Bradykinin - endothelial damage causes vasodilation
Outline basic molecular mechanism of an IgE mediated allergic response
Allergen specific IgE binds to mast cell + allergen = degranulation of mast cell
Vasoactive amines e.g. histamine produces response
Context for active hyperemia
Local increase CO2 or decrease O2 e.g. increased metabolic activity
Other cells involved in allergic response?
Basophils
Eosinophils
Define compliance/capacitance
amount of blood stored in a vessel per unit increase in pressure
What is a provocation test?
For challenge with foodstuff
Elimination diet (double blind placebo challenge)
What is tryptase?
Mediator released by mast cells
What is the main in vivo test used to diagnose an allergic reaction?
Skin Prick Test - wheal and flare reaction
What are 2 neural reflexes that control blood vessel diameter
Baroreceptor reflex (causes vasodilation)
Chemoreflexes (causes vasoconstriction in response to drop in O2 or rise in CO2)
What test is used to diagnose anaphylaxis
Serum tryptase
What are the 2 main vitro tests for diagnosing allergies?
Total serum IgE
Radioallergsorbent test (RAST)
What differentiates early phase vs late phase allergic reactions?
Early: mast cells and basophils activation
Late: eosinophil, neutrophil and TH2 migration
Define hypersensitivity:
Type I
Type II
Type III
Type IV
Immune based adversed reactions
1 - IgE mediated
2 - antibody mediated
3 - immune complex mediated
4 - cell mediated
Response to brain ischaemia (in terms of vessel diameter)
Increased vasomotor and cardio-acceleratory activity
Vasoconstriction and increased CO
Rise in MAP
Context for reactive hyperemia
Local increase CO2 or decrease in O2 as a result of blood supply cut off
4 outcomes of histamine
Arteriole dilation
Increased vascular permeability
Increased bronchial and GIT smooth muscle contraction
Increased mucus production
Outline tigger and result of NO release for vessel wall diameter
Triggers: sheer stress and sympathetic signals
Causes vasodilation - NO induces smooth muscle cell relaxation
What are the categories of treatment for allergies?
Avoidance
Pharmacological
Immunotherapy (desensitization)
Define atopy
tendency to produce IgE antibodies in response to low doses of allergen
What is Western/immunoblotting used for?
Research tool - to identify IgE reactive proteins i.e. allergens
What is the positive and negative control in the skin prick test?
+ histamine
- saline
What is the Serum eosinophil cationic protein (SECP) used for?
Monitor inflammation in asthma
