Flashcards in 2. Pneumocytes Deck (25):
Pneumonocytes - porportion of alveolar surface
97% type I celll
type I cell pneymonocytes area
line the alveoli
type I cell pneumonocytes - histology
type I pneymonocytes are thin because...
optimal gas exchange
type II cell pneumonocytes - histology
cuboidal and clustered
Type II pneumonocytes function
1. secrete pulmonary surfactant
2. serve as precyrsor to type I cells and other type II cells - they can proliferate during damage
Pulmonary surfactan is secreted by
type II cell pneumonocyte
2. Club (Clara ) cells
pulmonary surfactan - fumctopm
decreases alveolar surface tension and prevents alveolar collapse (atelactasis (decrease recoil and increased compliance
Club clara cells - histology
low columnar /cuboidal with secretory granules
Club (clara cells - function
1. secrete component of surfactant
3. act as reserve cells
lung - collapsing pressure (P) equation
P= 2 (surface tension) / radius
Laplace law in alveoli
alveoli have increased tendency to collapse on expiration as radius decreases
Pulmonary surfactant is a (chemistry)
complex mix of lecithins , the most important of which is dipalmitoylphosphatidycholine
Pulmonsty surgactant : mature levels achieved
around week 35
Pulmonary surfactant synthesis begins
around week 26 of gestation
• What is the advantage of having numerous thin type I pneumocytes line the walls of alveoli?
Maximum gas exchange is permitted by thin cells (squamous morphology)
What are two important functions of type II pneumocytes?
To secrete surfactant (prevent alveolar collapse) and to serve as precursors to other pneumocytes (both types I and II)
• A patient suffers a pneumothorax, which damages his lungs. Which cells proliferate to repair the lungs after they have been damaged?
Type II pneumocytes (they are the precursors of both type I and type II pneumocytes)
Describe club cells and their three functions. What is another (now outdated) name for them?
Nonciliated columnar/cuboidal pneumocytes with secretory granules that secrete surfactant, degrade toxins, act as reserve cells; Clara cells
Explain the law of Laplace using the equation for calculating collapsing pressure (P).
P = 2 (surface tension)/radius; alveoli have a tendency to collapse on expiration, because as their radius decreases, P increases
What is dipalmitoylphosphatidylcholine? What is its function?
A type of lecithin and an important component of surfactant; surfactant decreases alveolar surface tension and prevents atelectasis
A neonate is born at 32 weeks. Why will this neonate have respiratory problems?
Surfactant synthesis starts at 26 weeks but does not mature until 35 weeks—therefore, the child is more likely to have respiratory distress
A woman at 30 weeks' gestation presents for an exam. The ratio of which two amniotic fluid markers can be used to assess fetal lung maturity?
The lecithin:sphingomyelin ratio (marker for surfactant quantity)