lung structure and airway diseases Flashcards
What does the respiratory tract consist of?
nasal cavity and sinuses
larynx
trachea
bronchi
bronchioles
alveolar duct
alveoli
What does the conducting airways consist of?
trachea
primary bronchus
secondary bronchus
What does the resistance airways consist of?
bronchiole
terminal bronchiole
respiratory bronchiole
What does the respiratory airways consist of?
alveolar duct
alveolar sac
The bronchus is covered in…?
smooth muscle and elastic fibres
What lines the bronchus and bronchiole?
epithelium
What is the role of the pulmonary arteries and veins?
carry blood to (arteries) and from (veins) the lungs
Does the pulmonary veins carry O2?
yes
Does the pulmonary arteries carry CO2?
yes
What is the role of the bronchial arteries and veins?
supply blood to and drain from the airways
Do bronchial arteries carry O2?
yes
Do bronchial veins carry CO2?
yes
What type of epithelium lines the airway?
pseudostratified columnar
What is the role of the epithelium?
physical barrier (inhibits and prevents)
housekeeping role (ciliate cells)
catabolic metabolism (via cytochrome P450)
anabolic metabolism (synthesis of inhibitory mediators - PGE2)
What are the main nerve types?
cholinergic (excitatory)
noradrenergic (inhibitory)
inhibitory nonadrenergic noncholinergic (iNANC)
excitatory nonadrenergic noncholinergic (eNANC)
What role does the cholinergic nerves play?
major role in regulating airway smooth muscle tone and mucus production
What is the major role of iNANC?
release nitric oxide
innervates smooth muscle directly
relaxation
What is the role of eNANC?
release neuropeptides
increase airway tone, secretion of mucus and microvascular leakage
What is asthma?
chronic inflammatory disease of the airways characterised by bronchial obstruction and airflow limitation
Can bronchial obstruction and airflow limitation be reversible?
yes, either spontaneously or with treatment
What are the characteristics of asthma?
shortness of breath
wheeze
tight chest
cough
What are the two phases of the allergic response?
early phase response
late phase response
What happens during the early phase of an allergic response?
decrease in FEV1, peak at 30-40 minutes, resolved in 2-3 hours
mast cell-derived histamine and leukotrienes
What happens in the late phase of an allergic response?
release of inflammatory mediators cause submucosal oedema, airway wall swelling, secretion of mucus
epithelium remodelling, airway muscle hypertrophy/hyperplasia, subepithelial fibrosis
What is FEV1?
the amount of air forced from lungs in 1 second
What are the major characteristic features of asthma?
reversible bronchial obstruction
airway hyperresponsiveness
airway wall remodelling
What is bronchial obstruction in asthma caused by?
a range of endogenous mediators
What happens during bronchial obstruction?
increase airway smooth muscle tone; secretion of mucus
shedding of epithelium and accumulation of debris
oedema and selling of submucosa
airway smooth muscle hypertrophy + hyperplasia
sub-epithelial fibrosis
What causes airway hyperresponsiveness?
a range of unrelated stimuli - methacholine, histamine, cold air
What is the rule for airway resistance?
resistance to airflow is inversely proportional to the radius of the lumen raised to the fourth power
What happens during airway hyperresponsiveness?
airway resistance
airway narrowing
What happens during airway remodelling?
- dilated blood vessels
- infiltration of inflammatory cells - eosinophil; mast cell; mononuclear
- destroyed epithelium cells
- thickened basement membrane
- mucus plug with eosinophil and desquamated epithelial cells
- hypertrophied smooth muscle
Where is histamine stored?
in mast cells and basophils
When is histamine released?
in early phase response
What can histamine cause?
bronchoconstriction, airway wall oedema
What are the major histamine receptor antagonists?
H1 and H4
What is H1 receptor?
seasonal allergies
not useful in asthma
What is H4 receptor?
asthma, atopic dermatitis, psoriasis
When is leukotrienes released?
early and late phase response
What is LTB4?
chemoattractant for inflammatory cells
What is LTC4, LTD4, LTE4?
potent bronchoconstrictors
cause secretion of mucus
induce release of chemical mediators from inflammatory cells
What is COPD?
chronic obstructive pulmonary disease
What makes up COPD?
chronic bronchitis + emphysema
What are some primary causes of COPD?
tobacco smoking
air pollution
What is a treatment of COPD?
ipratropium bromide (muscarinic antagonist) + salbutamol (β2-adrenoceptor agonist)
What are the features of chronic bronchitis?
inflammatory disease with irreversible airflow limitation
hypersecretion of bronchial mucus
secondary respiratory infections
What types of drugs provide symptom relief for chronic bronchitis?
β2-adrenoceptor agonists
muscarinic antagonist
glucocorticoids
mucokinetic drugs
antibiotics
What is another way to treat chronic bronchitis?
selective phosphodiesterase IV inhibitors (roflumilast)
How does selective phosphodiesterase IV inhibitors help?
improves lung functions
decrease freq. of exacerbations
targets underlying inflammation
