Unit 3 Day 1 (Tue 4/21) Flashcards
1
Q
5 Phases of Lung Development
A
- embryonic stage
- pseudoglandular stage
- canalicular stage
- saccular stage (terminal sac stage)
- alveolar (postnatal stage)
2
Q
Embryonic Stage
A
- 1st stage
- 4-7 weeks
- branching morphogenesis
- branching pattern determined by mesoderm
3
Q
Pseudoglandular Stage
A
- 2nd stage
- 8-16 weeks
- differentiation of conducting airway epithelium
- glandular appearance
- formation of conducting airways completed at end of this stage
4
Q
Canalicular Stage
A
- 3rd stage
- 17-26 weeks
- characterized by formation of repiratory bronchioles (deliniation of pulmonary acinus)
- possible to survive but respiratory distress trouble likely
5
Q
Path of Air Into the Lungs
A
- trachea
- L and R primary bronchi
- secondary or lobar bronchi (3 in R lung, 2 in L lung)
- segmental bronchi
- terminal bronchioles (bronchioles do not have cartilage)
- respiratory bronchioles of exchange system
- alveolar ducts
- alveolar sacs
6
Q
Blood Flow In the Pulmonary System
A
- pulmonary arteries
- terminate in interalveolar network of capillaries
- does not supply oxygen to the conduction system, but picks up oxygen in alveoli
- oxygenated blood returns to heart in pulmonary veins
7
Q
Blood Flow in the Bronchial System
A
- bronchial arteries
- supply oxygen to the conduction system
- most blood in this system mixes with pulmonary supply through anastamoses with small pulmonary arterioles and capillaries
- bronchial veins drain only the connective tissues of hilar region of the lungs into the azygous vein
8
Q
Path of Air Into the Lungs
A
- trachea
- L and R primary bronchi
- secondary or lobar bronchi (3 in R lung, 2 in L lung)
- segmental bronchi
- terminal bronchioles (epitherlium contains club cells)
- respiratory bronchioles of exchange system
- alveolar ducts
- alveolar sacs
9
Q
Alveolar Septa
A
- indvidual alveoli are separated by interalveolar septa which are comprised of fibroelastic basal laminae and cells
- two main types of cells, type I and type II pneumocytes, are found on the side of the alveolar septa that faces air supply
10
Q
Passage of Gas Through Air Blood Barrier
A
- surfactant layer
- plasma membranes and cytoplasm of thin type I pneumocytes
- common basal lamina between type I cell and capillary epithelium
- plasma membranes and cytoplasm of edothelial cell
- thus, oxygen must diffuse though plasma membranes 5 times before reaching hemoglobin in a RBC
11
Q
Defense Mechanisms of the Alveoli
A
- alveolar tissues contains type I and II pneumocytes, monocytes, neutrophils, and fibroblasts
- monocytes differentiate into alveolar macrophages which enter the alveolar space and serve as third line of defense by phagocytosing small inhaled bacteria
12
Q
Surfactant
A
- mixtures of lipids and proteins with polar and non-polar ends
- secreted by type II pneumoytes
- lowers surface tension in alveoli and prevents lung collapse and lung drying
- primary component of surfactant is phospholipids
- lack of surfactant is major problem in premature births
13
Q
Cystic Fibrosis
A
- chronic congestive disease
- defect in chloride transport in epithelial cells
- autosomal recessive
- results in chronic infections and respiratory failure
14
Q
Kartagener’s Syndrome
A
- severe genetic defect characterized by respiratory congestion and infections
- results from immotile cilia, due to defects in dynein arms
15
Q
Particulate Overload Diseases (Black Lung, Silicosis)
A
- excessive smoking and/or air pollution leads to progressive loss of ciliated cells
- starts with loss of synchronized cilia wave
- cilia become gradually replaced with squamous cells as chronic coughing is used to clear congestion
