Cough: Mechanisms, Causes + Pharmacological Therapy Flashcards
What is a chronic cough?
> 8 weeks
What does the cough reflex involve?
Central + peripheral mechanisms
What is the central mechanism for a cough reflex?
Cough centre in medulla oblongata receives stimuli
Initiates reflex response
What is the peripheral mechanism for a cough reflex?
Cough receptors in pharynx, larynx, trachea or lungs
Stimulated by air, dryness of mucous or excessive secretions
Describe what happens when you cough
Cough receptor stimulated
Vagus + glossopharyngeal nerves transmit impulse to cough centre
Impulse transmitted to larynx + intercostal + abdominal muscles
Deep inspiration followed by closure of glottis, relaxation of diaphragm + contraction of muscles
Increased pressure = open glottis releases forceful expiration, cough
What are the 3 types of cough receptors?
Rapidly adapting receptors (RARs)
Slowly adapting receptors (SARs)
Nociceptors on C-fibres
Describe RARs
Respond to mechanical stimuli = smoke, ammonia, acidic/alkaline solutions
Describe nociceptors on C-fibres
Respond to chemical stimuli = histamine, prostaglandins
What is an example of exogenous source?
Smoke, dust, fumes, foreign bodies
What is an example of endogenous origin?
Upper air secretions, gastric contents
What is most common cause of chronic cough for a non-smoker?
Postnasal drip
When should a cough be evaluated?
Chest pain
Fever
Weight loss
Blood-tinged sputum
When is a cough productive?
Secretions are expectorated
When is a cough non-productive?
Dry, no sputum
What conditions are associated with dry cough?
Laryngitis
Smoking cough
Pneumonia
TB
Lung cancer
