Sensory Aspects of Respiration Flashcards
What are the typical symptoms of lung diseases?
Breathlessness (or dyspnoea) is a sensation of difficult or uncomfortable breathing. Cough Sputum production Haemoptysis Chest discomfort Wheeze Stridor Hoarseness Snoring history Daytime sleepiness
What may breathlessness be due to? (x5) IMPORTANT for when we become doctors.
NOT JUST lung disease. Heart disease. Pulmonary vascular disease. Neuromuscular diseases (e.g. diaphragm weakness). Systemic disorders (e.g. anaemia, hyperthyroidism, obesity). Equally, if someone has already been diagnosed with one of these diseases, and have exacerbated breathlessness, consider that they may have another one of the above listed diseases).
What is the epidemiology of lung disease?
Respiratory disease affects 1 in 3 in England. It is the third biggest cause of death, killing 1 in 5. Winter observes highest lung disease incidence.
What are the top three rankings for deaths from respiratory diseases?
Lung cancer. COPD. Pneumonia.
What is the prevalence of cough? (x2 points)
3rd most common GP complaint. 10-38% of respiratory outpatients complain of cough.
What is the prevalence of chest pain?
Most common pain for patients seeking medical help (35%).
What is the prevalence of dyspnoea? (x2 points)
6-27% of the general population and 3% of visits to A&E.
What is the difference between symptoms and signs? Examples in the context of respiratory diseases? (x3 and x3)
SYMPTOMS: abnormal or worrying sensation that leads person to seek medical attention e.g. cough, chest pain, dyspnoea. SIGNS: observable features on physical examination e.g. hyperinflation, dullness on percussion and increased respiratory rate.
What is the purpose of a cough? (x2)
Crucial defence mechanism to protect large respiratory tract from inhaled foreign material and excessive mucous secretion. Secondary to mucociliary clearance.
Where are the respiratory sensory receptors located?
Present in the upper airways, larynx and the trachea. Less numerous in the more distal airways and absent beyond respiratory bronchioles.
What are the three types of sensory receptor in the respiratory system: Where? Stimulus? Structure? Function?
THESE ARE ALL IRRITANT RECEPTORS. C-FIBRE RECEPTORS: stimulated by chemicals. Free nerve endings are found in the larynx, trachea, bronchi and lungs that are unmyelinated and release neuropeptide inflammatory mediators (Neurokinin A, Calcitonin Gene Related Peptide, Substance P) in response to inflammatory mediators and chemical stimuli. RAPIDLY ADAPTING STRETCH/IRRITANT RECEPTORS: stimulated by stretch on inspiration. Found in the nasopharynx, larynx, trachea and bronchi. They are small, myelinated fibres that respond to mechanical, chemical and inflammatory stimuli. These are what INDUCE COUGH and respond to stretch in inspiration. SLOWLY ADAPTING STRETCH RECEPTORS: located in airways smooth muscle, predominantly in the trachea and main bronchi. They are myelinated nerve fibres and mechanoreceptors – respond to lung inflation.
What is the afferent neural pathway (involved in cough)? (x1 +1) What are the receptors associated with the afferent neural pathway and their structure? (x2)
These are the sensory nerves that take signals from the sensory nerves to the CNS. IRRITANT RECEPTORS are stimulated, and their afferent neurone is the VAGUS NERVE which travels to the cough centre in the MEDULLA. The superior laryngeal nerve is a branch of the vagus nerve – look at photo. IRRITANT RECEPTORS – mechanoreceptors (cell bodies located in the nodose ganglion, and sensory receptors activated by mechanically-gated ion channels), and nociceptors (cell bodies located in the jugular ganglion) that detect chemicals such as bradykinin and citric acid.
What do mechanical and nociceptors respond to?
MECHANICAL: dust, mucous, food/drink. NOCICEPTORS: noxious, intrinsic inflammatory agents. Nociceptors responds to damaging or potentially damaging stimuli by sending “possible threat” signals to the spinal cord and the brain. If the brain perceives the threat as credible, it creates the sensation of pain.
What are the efferent neural pathways involved in cough?
Activation of motor pathways to effect changes in breathing to cause expiratory airflow (control glottic muscles and expiratory muscles (diaphragm, intercostals, laryngeal muscles, abdominal muscles – refer to photo)). Cough centre is influenced by the cerebral cortex.
What are the mechanics of cough?
- Inspiratory phase with negative flow during inhalation. 2. Glottic closure produces build-up of pressure and minimum air flow – hence called minimum flow phase. 3. Glottis opening. 4. Expiratory phase: this is the expulsive phase, which generates high velocity airflow, facilitated by bronchoconstriction and mucous secretion.
What does a cough sound waveform look like and why?
2 phases with an initial explosive phase that is the first cough sound, followed by an intermediate phase with decreasing sound. An additional third phase called a voiced or glottal phase which gives rise to a second cough sound. [PHOTO 4].
What happens to the trachea during a cough?
When you initially inspire, trachea is round. THEN COMES THE COUGH – intrathoracic pressure causes the posterior tracheal membrane to invaginate = narrows the airways.
What are the spinal pathways for TOUCH and PAIN in the respiratory system?
PATHWAY THAT CONVEYS TOUCH: uses the dorsal columns. Fibres enter the dorsal horn into the spinal column, passing up dorsal columns (the posterior columns in the white matter of the spinal cord). Then, fibres switch at the medulla, passing through to the thalamus and then to the primary somatosensory cortex.
PATHWAY THAT CONVEYS PAIN: A-delta and C fibres enter via the dorsal column of the spinal cord, then immediately crosses over at level of entry (rather than at the medulla) and uses the spino-thalamic tract (another ascending pathway of the spinal cord that conveys pain). Then, it passes into thalamus and to the primary somatosensory cortex.
What two rating scales can be used to assess dyspnoea?
MODIFIED BORG scale and CLINICAL DYSPNOAE scale (American).
