Protective Receptors Flashcards
What are nasal receptors sensitive to?
Irritating stimuli mechanical and chemical
What does nasal receptor stimulation cause?
Sneezing/apnoea
Bradycardia
Selective vasoconstriction
What does laryngeal receptor stimulation cause?
Coughing
slow deep breathing/apnoea
laryngospasm
bradycardia
vasoconstriction
What does tracheal receptor stimulation cause?
coughing
slow deep breathing/apnoea
bradycardia
selective vasoconstriction
What are the medical importance of these responses?
Prevention of aspiration
intubation and endoscopic procedures
diving reflex
drowning
treatment of supra-ventricular tachycardia
What are the 3 intrapulmonary receptors?
Irritant receptors
J receptors
Pulmonary stretch receptors
Where are irritant receptors located?
Airway epithelium, myelinated vagal afferents
What are irritant receptors sensitive to?
Mechanical and chemical simulation
histamine
what does irritant receptor stimulation cause?
Hyperpnoea
Increased tidal volume
bronchoconstriction
Where are J receptors located?
Beside pulmonary capillaries
nonmyelinated vagal afferents
What are J receptors sensitive to?
Irritant chemicals in pulmonary arterial blood
What does J receptor stimulation cause?
Rapid shallow breathing
apnoea
hypotension
bradycardia
Where are pulmonary stretch receptors located?
In airway smooth muscle, myelinated vagal afferents
What are pulmonary stretch receptors sensitive to?
Lung distension
What does stimulation of pulmonary stretch receptors cause?
Inhibition of inspiration
dilation of airways
tachycardia
vasoconstriction
What happens to these receptors in a vagotomy?
Low frequency, high tidal volume patterne of ventilation
What do cholinergic nerves travel via?
Via vagus to parasympathetic ganglia within airway walls
What do postganglionic fibres run to?
airway smooth muscle, epithelium and submucosal glands
Where are vagal fibres most dense?
Large airways reduce peripherally
What does electrical stimulation of vagus cause?
Bronchoconstriction
Mucus secretion
What drug can prevent bronchoconstriction ?
muscarinic antagonist (M3 subtype bronchoconstriction)
What do muscarinic receptor antagonists cause in low normal vagal tone?
Minor bronchodilation
What do anti-muscarinic agents cause?
Beta2 and M2 receptors on pre-junctional efferent vagal fibres inhibit ACh release
What sympathetic receptor is expressed on airway?
Beta2 adrenergic receptors
What does adrenaline and noradrenaline cause?
Bronchodilation
What is the only neural bronchodilator pathways in humans?
Inhibitory NANC (NO mediated)
What does excitatory NANC cause?
Bronchoconstriction (neuropeptide mediated)
How is astham treated?
Beta2 agonists - bronchodilation
How is COPD treated?
Anti-muscarinics antagonists - bronchodilation
What does increased drive to vagal motor tone from airway irritant receptors cause?
Inflammatory mediators
epithelial damage
