Itches, scratches and Sneezes Flashcards
Allergic response
Outline the allergic response
- Allergen
- white blood cells respond to allergen with antibodies
- memory cells remember antigen
- when re-exposure occurs, allergen is engulfed and digested
- mast cells then release inflammatory mediators
functions of mast cells
what 3 things do mast cells release when allergens or pathogens bind to them
they release:
- histamine
- prostaglandins and leukotrienes
- cytokines
functions of mast cells
what is does histamine, LTC4 and PGD2 do to epithelial permeability?
increases epithelial permeability and secretion
functions of mast cells
what can histamine and LTC4 also affect other than epithelial permeability
can effect:
- blood flow
- vascular permeability
- coagulation
functions of mast cells
what can histamine, proteases and PGD2 do in the nervous system, gastrointestinal tract and bronchi
can:
- have neuroimmune interactions
- aid peristalsis
- cause bronchoconstriction
- can cause pain
pharmacological strategy
what are 4 phamacological strategies to decrease immune mediator action
- immunotherapy
- prevent release of mediators from mast cells
- block action of mediators using a receptor antagonist
- inhibit synthesis of mediators
Preventing Release
what does cromoglicate do and what can it be used in
cromoglicate stabilises mast cells, inhibiting degranulation (stopping release of inflammatory mediators)
used in:
- eye drops
- nasal spray
- some times asthma
histamine
what 3 things does H1 histamine receptor subtype cause
causes:
- contraction of smooth muscle (ileum, bronchi, uterus)
- vasodilation
- plasma exudation
antihistaminnes: 1st Gen
why do diphenhydramine, dimenhydrinate, chlorpheniramine and promethazine cause drowsiness?
because they cross they cross the blood brain barrier
antihistamines: 2nd and 3rd Gen
what Generation antihistamine is terfenadine, why is it non-sedating and why was it withdrawn infavour of newer generation antihistamines?
- 2nd generation
- non-sedating as does not cross BBB
- withdrawn as it can cause arrhytmias (irregular heartbeat)
antihistamines: 2nd and 3rd gen
name 3 third generation antihistamine drugs
- fexodenadine
- cetirizine
- loratadine
Synthesis of Prostagladins and leukotrienes
how are prostagladins and leukotrienes synthesised?
from membrane phospholipids that are broken down to form arachidonic acid
synthesis of prostaglandins and leukotrienes
outline how prostaglandins and leukotrienes are synthesised
- membrane phospholipids are cleaved using phospholipase A2.
- this releases arachidonic acid, which is acted upon by cyclooxygenase (COX), leading to to production of protaglandins
- arachidonic acid are also acted by lipoxygenase, leading to production of leukotrienes
Prostaglandins
what receptors do PGI2 act on and what are the effects of activation of this receptor
- acts on IP receptors
- effects include:
vasodilator
production of pain
inhibits platelet aggregation
Prostaglandins
what receptors does PGF2a act on and what are the effects of activation of this receptor?
- acts on FP receptors
- effects include:
bronchoconstrictor
myometrial contraction
coughs
prostaglandins
what receptors does PGD2 act on and what are the effects of activation of this receptor
- acts on DP
- effects of activation:
vasodilator
broncho-constriction
chemotaxis
inhibits platelet aggregation
Prostaglandins
what receptors does PGE2 act on and what are the effects of activation of this receptor
- acts on EP receptors
effects:
- vasodilation
- pain
- cough
- mucus secretion
prostaglandins
what receptors does TXA2 (thromboxane) act on and what are the effects of activation of this receptor
- acts on TP receptors
effects:
- vaso-constriction
- increases platelet aggregation
prostaglandins
what prostaglandins do these cells produce:
- platelets
- endothelium
- mast cells
- many other cells
NSAIDs
what do NSAIDs inhibit?
NSAIDs are COX inhibitors
NSAIDs
How can NSAIDs be antipyretic
they can be antipyretic due to inhibition of prostaglandin production in the hypothalamus (eg paracetamol)
paracetamol is NOT anti-inflammatory
Leukotrienes
what 2 things do LTC4, LTD4 and LTE4 do?
- bronchoconstriction
- increased microvascular permeability
leukotrienes
what 2 things does LTB4 do?
- Chemoattractant for neutrophils
- Stimulates release of lysosomal enzymes from macrophages
leukotrienes
what can zileuton do?
can inhibit lipoxygenase, stopping production of leukotrienes
