Respiration III Flashcards
What is involved in control of airway diameter
airway smooth muscle, parasympathetic control, sympathetic control, NANC signalling
What is NANC signalling
non adrenergic, non cholinergic signalling
What is needed to initiate smooth muscle contraction
increased cytoplasmic calcium levels
What activates myosin light chain kinase
calcium carmodulin complex
What allows smooth muscle contraction to take place
phosphorylated myosin light chain
What inhibits myosin light chain kinase
cyclic AMP
What inhibits light chain phosphatase
Gq pathways
What happens when light chain phosphatase is inhibited
muscle contraction
What does the Gq pathway increase
calcium
What is the importance of G proteins in smooth muscle contraction
activation of contraction
What G pathways are involved in the control of airway smooth muscle
Gq, Gs, Gi
What does the binding of agonists to the receptor in airway smooth muscle activate
activated form of Gq alpha subunit
What does activated form of Gq stimulate
phospholipase C
What does phospholipase C act on
PIP2
what does IP3 stimulate
release of calcium from stores
What does calcium bind to in the cytoplasmic space
carmodulin
What is the function of calcium carmodulin
activate myosin light chain kinase
what receptors act through the Gq pathway
M3 muscarinic receptors, H1 histamine receptors, BK bradykinin receptors
What is the effect of Gq activation on smooth muscles
contraction
What is the effect of Gs activation on smooth muscles
muscle relaxation
What is the effect of hyper polarised membrane on calcium movement
reduces influx of calcium
What receptors act in the Gs pathway
B2 adrenergic receptors and VIP receptors
Which pathway inhibits the Gs pathway
Gi pathway
What is the effect of the Gi pathway
opposes the relaxation of smooth muscle, inhibits BK potassium channel
Which receptors are active in the Gi pathway
M2 muscarinic receptors
Where are M2 receptors located
postganglionic terminal
What are M2 receptors involved in
negative feedback system for Ach
What neurotransmitter stimulates M3
Ach
Where are M3 located
airway smooth muscle
Where are M1 and M3 receptors also located
epithelial cells
What is the effect of stimulating M1 and M3 cells in the submucousa gland
mucous production
What does smooth muscle contraction in the airways cause
decreased air flow and increased resistance
What is the importance of the M2 receptors on the nerve fibre
binding of Ach to M2 prevents over release of Ach
What can disruption of the M2 negative feedback loop lead to
hypersensitivity of the airways
What do B2 adreno receptors respond to
noradrenaline or adrenaline
What nervous system uses B2 adrenoreceptors
sympathetic
What is the final effect when an agonist binds to B2 adrenoreceptors
muscle relaxation
What pathway does salbutamol stimulate
B2 adrenoreceptors
What are the two NANC pathways
excitatory and inhibitory
What does the excitatory NANC pathway cause
broncho constriction
What are the transmitters involved in the NANC excitatory pathway
neuropeptide Y, nitric oxide and VIP
what does the inhibitory NANC pathway cause
broncho relaxation
What transmitters are involved in the NANC inhibitory pathway
substance P/neurokinin
What are the two classes of asthma
Atopic and Non-Atopic
Which type of asthma is linked to allergies
Atopic
What is asthma
chronic airway disorder with variable and recurring symptoms
What are the symptoms of asthma
airflow obstruction, bronchial hyper responsiveness, inflammation
what is more likely in hyper responsiveness
airways will restrict
What is the biology behind atopic asthma
elevated serum IgE levels, positive prick test to allergen
What activates inflammatory cells in atopic asthma
hyper sensitivity of M2 receptor
What is the biology behind non atopic asthma
non-positive skin prick test and normal IgE levels
When is non atopic asthma most common
elderly, cold air, exercise induced asthma
True or false - Ach can bind to different white blood cells and trigger inflammatory responses
true
What was the effect of treatment for airway hyper sensitivity
decreased neuronal M2 function
What clusters around nerve fibres
eosinophils
What do eosinophils release
major basic protein
What is the effect of major basic protein on M2 receptors
inhibits M2
What is the effect of inhibiting M2
increases release of Ach
What is the effect of increasing Ach levels
airway constriction
What drugs can treat asthma
anti cholinergic drugs
What is the advantage of anti cholinergic drugs
reverse broncho constriction and prevent mucous secretion
What do anti cholinergic drugs inhibit
M1, M2, M3 receptors
Which receptors do anti cholinergic drugs bind to the longest
M3
Name a short lasting anti cholinergic
ipratropium
Name a long lasting anti cholinergic
titropium
What are anti cholinergics used alongside of
B2 adrenoreceptor agonists
