Respiratory Systems 9 - Sensory Aspects of Respiratory Symptoms Flashcards
Define symptoms
An abnormal or worrying sensation that leads the person to seek medical attnetion
Define physical sign
An observable feature on physical examination
Describe the pathway of conscious sensation
- Sensory stimulus causes excitation of a sensory nerve, which results in a sensory impression
- Perception and evoked sensation follow
List the causes of coughs
- Acute infections and airway diseases (eg. COPD/Asthma)
- Cronic infections (TB)
- Parenchymal diseases (fibrosis)
- Tumours
- Cardiovascular diseases
- Gastroesophageal reflux disease
Describe the location of cough receptors
- Most numerous on the posterior wall of the trachea
- At the main carina, and branching points of large airways
- Absent beyond the respiratory bronchioles
- In the pharynx
Describe the function of cough receptors
- Rapidly adapting irritant receptors located within the airway epithelium
- Respond to chemical and mechanical stimuli
List the sensory receptors in the lung and airways
- C-fibre receptors
- Rapidly adapting stretch receptors
- Slowly adapting stretch receptors
List the functions of C-fibre receptors in the airways
- Free nerve endings
- Larynx, trachea, bronchi and lungs
- Respond to chemical irritant stimuli, inflammatory mediators
- Release neuropeptide inflammatory mediators
What are rapidly adapting stretch receptors in the lung? Location, structure and stimuli.
- Naso-pharynx, larynx, trachea, bronchi
- Small, myelinated nerve fibres
- Respond to mechanical and chemical irritant stimuli
What are slowly adapting stretch receptors in the lung and airways? Location, structure, and stimuli
- Located in the smooth muscle, predominantly in the trachea and main bronchi
- Myelinated nerve fibres
- Mechanoreceptors, so respond to lung inflation
List the afferent nerve pathways for cough
- Mainly the vagus nerve
- Also superior laryngeal nerve
- Goes to the cough centre in the medulla which sends signals to the cerebral cortex
Describe the causes and duration of an acute cough
- Lasts less than 3 weeks
- Caused by a common cold
Describe the causes and duration of a chronic persistent cough
> 3 weeks
- Asthma/eosinophilic associated
- Gastro-oesophageal reflux
- Chronic brochitis
- ACE inhibitors
- Post viral/idiopathic
Describe cough hypersensitivity syndrome
- Irritation in the throatm or upper chest
- Difficult to control
- Triggered by deep breaths, laughing, talking, vigorous exercise, smells, cigarette smoke, cold air
How does plasticity of neural mechanisms relate to cough?
- Excitability of nerves increases
- Increase in receptor numbers
- Neurotransmitter increase
List the muscles involved in the cough reflex
- Diaphragm
- Intercostal muscles
- Laryngeal muscles
- Abdominal muscles
List the treatments for cough
- Opiates such as codiene/morphine suppress symptoms
- Disease-specific therapies include inhaled corticosteroids if eosinophil associated, and propton pump inhibitors for gastro-oesophageal reflux disease
List treatments for cough hypersensitivity syndrome
- Amitryptiline
- Gabapentin
- Opiates
List the locations of sensory input from the lungs for chest pain.
- Trigeminal nerve in the nose
- Glossopharyngeal nerve and vagus nerve supply the pharynx
- Larynx and lung supplied by the vagus nerve
- Chest wall supplied by spinal nerves
Describe the pathway taken in chest pain
- A delta/C-fibres via dorsal horn
- Passesthrough the spino-thalamic tract to the thalamus and then to primary somatosensory cortex
List the different types of pain
- Visceral pain from organs, it is hard to localise
- Somatic pain is from skin
List causes of chest pain relating to the respiratory system
- Pleuropulmonary disorders (infection, pneumothorax, embolism)
- Trachobronchitis
- Inflammation/trauma to the chest wall
- Reffered pain - shoulder pain due to diaphragmatic irritation
List the non-respiratory causes of chest pain
- Cardiovascular disorders (MI, pericarditis, aneurysm)
- Gastrointestinal disorders (gastroesophageal reflux)
- Psychiatric disorders (panic disorder/self-inflicted)
What is nociception?
The response of the sensory nervous system to pain, including chemical, mechanical or thermal stimulation
How is dyspnea assessed clinically?
- From 0 to 4, 4 being very severe, too breathless to leave the house (clinical dyspnea scale)
- 1-10 (intensity of sensation, Borg scale)
- Descriptor clusters (air hunger cluster, tightness cluster, work/effort cluster)
- Exercise testing
- Quality of life related
List the disorders presenting with dyspnea
- Impaired pulmonary function (COPD, asthma, stenosis, fibrosis, neuromuscular weakness)
- Impaired cardiovascular function (heart failure, valvular disease, pericardial disease)
- Altered central ventilatory drive (systemic or metabolic disease, anaemia, acidosis)
List the treatments for dyspnea
- Treat the cause
- Bronchodilators
- Morphine/diazepam
- Lung resection
- Pulmonary rehabilitation (improvement of fitness)
