Histology of the respiratory system Flashcards
What is the conducting portion of the respiratory tract?
nasal cavity, pharynx, larynx, trachea, main bronchi, lobar bronchi, segmental bronchi, terminal bronchioles
What is the respiratory portion of the respiratory tract?
Respiratory bronchioles, alveolar ducts, alveoli
What is the epithelium that lines the structures of nasal cavity to largest bronchioles?
pseudo stratified ciliated epithelium with goblet cells
What epithelium lines the terminal bronchioles?
simple columnar epithelium with cilia and clara cells - NO GOBLET
What epithelium lines the respiratory bronchioles and alveolar ducts?
simple cuboidal epithelium with sparsely scattered cilia and clara cells
What epithelium lines the alveoli?
simple squamous, type 1 and 2 pneumocytes
What is the anatomy of the trachea
C shaped hyaline cartilage rings completed posteriorly by a muscle trachealis
What is pseudo stratified epithelium?
All cells make contact with the basement membrane but not all reach the epithelial cell surface - nuclei lie at different levels
What is secreted from epithelium and submucosal glands in the trachea and bronchi?
mucins water serum proteins lysozyme to destroy bacteria antiproteases lymphocytes IgA
What is the difference between the main and the secondary/tertiary bronchi?
Histology similar excepts cartilages arranged as irregular crescent plates/islands rather than rings
Whats the difference between a bronchus and a bronchiole?
Bronchus - small diameter with cartilage reduced to small islands and glands in submucosa
Bronchiole - no cartilage or glands
Why is absence of cartilage in walls of bronchioles problematic?
it allows air passages to constrict and close down when smooth muscle contraction becomes excessive - asthma
What is asthma?
bronchoconstriction causing more difficulty with expiration than inspiration as normally the bronchial wall are held open by the surrounding alveoli
What do clara cells do?
secrete a surfactant lipoproteins preventing the walls sticking together during expiration
Why is important that there are no goblet cells in the terminal bronchioles?
they are the smallest portion of the conducting system and as the airways are very narrow you wouldn’t want someone drowning inter own mucus
