Lung Cell Biology Flashcards
How many generations of gas exchange units are there?
23
What proportion of epithelial cells are goblet cells?
1/5
How do goblet cells and mucus change in smokers?
Goblet cells INCREASE in number
Secretions INCREASE in quantity
Secretions are THICKER
What is the structure of mucus?
A thin sol phase overlays the cells
A thick gel phase is at the mucus-air interface
What does mucus contain?
Mucin protein, proeoglycans, GAGs - give viscoelasticity
Serum derived proteins - albumin + alpha-1 antitrypsin + alpha-1 proteinase inhibitor
There are also antiproteases that have been secreted by the epithelia.
Anti-oxidants
What proportion of epithelial cells are ciliated cells?
80%
How do ciliated cells change in smokers?
Ciliated cell are severely depleted
Beat asynchronously
Ciliated cells found in bronchioles (though reduced in airways)
Unable to transport thickened mucus - smoker’s cough
Give two characteristics of small airways.
< 2 mm in diameter
NOT cartilaginous
What are clara cells?
Non-ciliated secretory epithelia found in the large, central and small airways and bronchi and bronchioles
How are clara cells distributed throughout the respiratory system?
They increase in proportion distally
What is the major role of clara cells?
Xenobiotic metabolism
What are the two classes of enzymes produced by clara cells and what do they do?
Phase 1 and Phase 2 - they are meant to be involved in metabolising foreign substances but they are also implicated in oncogenesis.
Phase 1 enzymes convert procarcinogens to carcinogens
Phase 2 enzymes conjugate the carcinogens to make them inactive
Clara cells also produce antiproteases and lyoszyme.
What is a potentially detrimental action of clara cell enzymes?
They convert procarcinogens into carcinogens
How are alveoli different in emphysema?
They have holes in them
Volume of alveoli increases
Surface area of the alveoli decrease
How do Type I and Type II cells differ in their susceptibility to damage?
Type II cells are more susceptible to damage
But Type I cells are more frequently damaged