Structure and function of the airways

Question 1

Explain the cholinergic mechanism in the air ways

Answer 1

irritants can cause an impulse to pass up the sensory fibre which causes a cholinergic reflex which contracts smooth muscle and causes secretion of mucus
You may get vasodilation
contraction and secretion is under cholinergic control
There is smooth muscle around the airways which contracts in response to acetylcholine

Question 2

What is the neurotransmitter and receptor?

Answer 2

Acetylcholine and muscarinic reeptor

Question 3

What is airway remodelling?

Answer 3

airways changes in structure over a long period of time

airway inflammation leads to remodelling

Question 4

ASthma: pathophysiology ‘schema’

How does asthma cause a central cholinergic reflex?

Answer 4

PAF (platelet activating factor) causes plasma exudation
ATP causes goblet cell exocytosis
We have epithelial fragility which exposes the sensory nerves which can respond to different mediators produced by inflammatory cells
This sets up central cholinergic reflex
This cholinergic reflex causes smooth muscle contraction and shutting down of the airways
The cholinergic reflex will also cause mucus secretion
This repeated bronchocontriction and mucus hypersecretion is associated with hypertrophy of the smooth muscle and the glands
There is an increase in the number of goblet cells
Chemical mediators are produced and released by these cells
Mast cells produce mediators which cause bronchoconstriction, mucus secretion etc