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21 Cards in this Set
- Front
- Back
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cough reflex has three different components? |
afferent sensory limb central processing centre efferent limb |
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three main groups of nerve fibres? |
rapidly adapting stretch receptors c-fibres slowly adapting stretch receptors |
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RARs... |
terminate slightly beneath the epithelium throughout the intrapulmonary airways, responding to changes in airway mechanics to regulate normal breathing these fibres fire in response to most tussive stimuli |
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c-fibres... |
have a higher threshold than RARs respond to chemical and mechanical stimuli c-fibres dont incite cough but might be involved in the sensitization of the cough reflex |
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SARs... |
not altered by stimuli that evoke cough not directly involved in the cough reflex however they might facilitate the cough reflex via interneurons |
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afferent and efferent nerves in the vagus nerve... |
afferent sends the stimulus to the brain efferent sends the response from the brain to the muscle cells |
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categories of cough... |
acute - less than three weeks subacute - 3-8 weeks chronic - more than 8 weeks |
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acute cough... |
max of three weeks commonly cause by URT infections, bronchitis or bacterial or viral infections |
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subacute cough... |
lasting 3-8 weeks following a specific infection, an increase in bronchial hyper-responsiveness may persist causing a sub acute cough that can remain bothersome for a number of weeks even after the original infection has been resolved |
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chronic cough... |
associated with asthma and COPD etc in some cases drugs can be used to inhibit the underlying inflammatory process however there are some patients whose cough doesnt respond to treatments directed at the cause of the cough |
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GORD |
Gastro-oesophageal reflux disease possibility that refluxed acid is inhaled unlikely most evidence points to activation of sensory receptors in distal oesophagus cough inhibited by ipratropium bromide, possibly by inhibition of mucus secretion |
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ACE inhibitors... |
airway peptidases are inhibited bradykinin and tachykinin can accumulate which stimulates sensory nerves leading to cough |
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cough suppressants (anti-tussives) |
peripherally acting cough suppressants local anaesthetics (lidocaine etc) inhibit voltage gated sodium channels thereby reducing action potential generation and transmission in afferent nerves tachykinin receptor antagonists tachykinin found in peripheral endings of C-fibres vanilloid receptor antagonists antagonise TRPV1 receptors in afferent neurons leukotriene receptor antagonists bradykinin receptor antagonists bradykinin activates c-fibres and can induce coughing in asthmatic subjects |
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centrally acting cough suppressants |
narcotic opioids such as codeine and morphine generally used in dry cough however can cause addiction and respiratory depression codeine most recommended for antitussive therapy out of the opioid class |
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cough in palliative care... |
methadone and diamorphine have been used to treat distressing cough in terminal lung cancer morphine now preferred |
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combination products... |
most combination drugs are unsuitable for children, although more justifiable in adults |
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antihistmines... |
added to many cough and cold remedies to treat rhinorrhoea and nasal congestion antihistamines do not appear to have any direct antitussive effect but it has been proposed that they may act indirectly by reducing post nasal drip |
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Expectorants... |
act peripherally increase bronchial secretion decrease its viscosity - facilitates its removal by coughing loose cough - less tiring and more productive classified into: directly acting or reflexly acting |
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demulcents (linctus)... |
liquid which coats the throat and soothes irritated mucus membranes consist primarily of sugar increase saliva production and swallowing, interfering with the cough reflex or coating the receptors that trigger the cough |
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mucolytics... |
help expectorants by liquefying the viscous secretions |
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menthol... |
cough medicine, lozenges or tablets local anaesthetic effect on nerve receptors with the respiratory tract |
