lung ventilation Flashcards
What happens in bronchitis
Mucus hyper secretion from goblet cells and reduced cilia so lack of mucus clearing
How do bronchus and bronchioles differ
A small bronchus has the presence of small islands of cartilage and glands in the submucosa which bronchioles do not.
How is a bronchioles defined
1mm or less in diameter
What is emphysema
Abnormal, permanent enlargement of the air space distal to the terminal bronchioles and destruction of alveolar walls and alveolar collapse.
what are the causes of emphysema?
Smoking may breakdown elastin or caused by protease mediated destruction of elastin (alpha 1 antitrypsin deficiency) meaning large air spaces.
what is asthma?
chronic inflammatory disorder of the airways causing airway narrowing and excess mucous production. airflow is most impeded during expiration. it is reversible.
Describe how emphysema leads to its symptoms and what pattern does it show on spirometry?
Loss of elastin means compliance increases but recoil if reduced. Damaged alveoli mean less radial traction so bronchioles collapse and air is trapped in pockets, resulting in a hyper inflated barrel chest. obstructive pattern on spirometry.
Symptoms of COPD?
shortness of breath, reduced exercise tolerance, cough
How do lung x rays differ in emphysema?
more ribs visible and flattened diaphragm
What is the interstitium in the lungs
a microscopic/potential space between alveolar epithelium and capillary endothelium (only becomes apparent in diseased states)
what is interstitial lung disease
heterogenous group of disorders characterized by alveolar septal thickening, fibroblast proliferation, collagen deposition and if left unchecked pulmonary fibrosis
What is contained within the lung interstitium
Elastin fibres, collagen, fibroblasts, matrix
What is idiopathic pulmonary fibrosis and what does it lead to?
Fibrosis of lung interstitium leading to decreased gas exchange (can be end result of interstitial lung disease)
What are some causes of interstitial lung disease
Asbestosis, silicosis , pneumoconiosis, radiation, chemo, nitrofurantoin, amiodarone, SLE, sarcoidosis or 20% idiopathic (fibrosis alveolitis), hypersensitivity pneumonitis.
What is hypersensitivity pneumonitis?
an immunologically mediated lung disease caused by repetitive inhalation of antigens which leads to interstitial lung disease. mostly caused by birds, or mould on certain crops.
What is pneumoconiosis?
interstitial lung disease caused by inhalation of dust such as coal
How does lung fibrosis effect lung ventilation and perfusion?
Reduced compliance and increased recoil meaning lung volume is smaller, diffusion distance is greater which effects O2 greater than CO2. Restrictive on spirometry. reduced perfusion- effect of diffusion is greater on O2 as CO2 is more soluble.
What are the symptoms of lung fibrosis/ interstitial lung disease
Breathlessness, dry cough, occupation and drug history, reduced exercise tolerance.
what are the signs of lung fibrosis/ interstitial lung disease?
reduced chest expansion, tachypnoea, tachycardia, fine crackles.
How is the increase in lung volume maximised during forced breathing?
Use of the inspiratory reserve volume IRV
how is the decrease in lung volume maximised during forced breathing
Use of the expiratory reserve volume ERV
How will emphysema effect functional residual capacity?
Increased
How will lung fibrosis effect functional residual capacity
Reduced
What is neonatal respiratory distress syndrome NRDS
Preterm babies under 35 weeks don’t produce enough lung surfactant to keep the alveoli open so they collapse and exogenous surfactants must be given
How does NRDS effect ventilation
high surface tension means incomplete lung expansion and some alveoli remain collapsed and do not partake in gas exchange. Respiratory difficulty results in impaired ventilation
What are the clinical features of NRDS?
grunting, nasal flaring, intercostal and subcostal retractions, tachypnea, cyanosis
What’s the treatment for NRDS?
surfactant replaced via an endotracheal tube, oxygen and assisted ventilation
What is a pneumothorax?
air in the pleural space due to a breach in the chest wall or lung. Loss of the pleural seal means the lungs elastic recoil isn’t countered, lung compression collapse.
What is resorption lung collapse
Collapse due to obstruction of a large airway such as in cancer or mucus plugs
What is atelectasis
Alveoli not ventilated and alveolar collapse (lung collapse). A common post operative complication
Where the alveoli aren’t ventilated sp can’t participate in gas exchange -> impaired oxygenation and co2 elimination
collapsed alveoli are more suggestible to lung infection including pneumonia
what is compression atelectasis
secondary to increased pressure exerted on the lung causing alveoli to collapse. resulting from pneumothorax or pleural effusion
what is resorption atelectasis
complete obstruction of an airway and over time air is resorbed from the alveoli, which collapse. can be caused by bronchial carcinoma.
What are some causes of hypoventilation
Guillain-Barré syndrome, trauma, opiates, head injury, myasthenia graves, inherited muscle disease, severe obesity, pneumothorax, large pleural effusions, NRDS, laryngeal oedema, severe acute asthma, late stages of COPD
What is a cough
An explosive expiration of air from the lungs which is co-ordinated by the cough centre in the medulla oblongata. It’s initiated by irritation of mechano and or chemo receptors in the respiratory epithelium, this travels through the vagus nerve and impulses come back from the cough centre through the vagus, phrenic and spinal motor never Ss to the diaphragm, abdominal wall and muscles
What are the steps involved in a normal cough
Vocal cords abduct, deep inspiration, glottis closed by vocal cord adduction, strong contraction of the expiratory muscles which builds intrapulmonary pressure, sudden opening of the glottis causes an explosive discharge of air.
