CAPS 390 Lecture Notes - Lecture 27: Exocrine Gland, Cystic Fibrosis, Pulmonary Artery
18 Nov 2015
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Reading : chapter 15 pp354- 365. Lecture 27 respiratory ii, november 5th, 2014 (dr. roskelley) Conducting portion of respiratory system (cont"d) Begin at the bifurcation of the trachea and branch ~8 times in each lung. Diameter decreases with each branching. Branches of pulmonary artery (low o2 ) and veins (high o2 ) run in adventitia. Consequently, cilia cannot beat efficiently to clear debris. Branch approximately 6 more times to reach terminal bronchioles (end of conductive portion of respiratory tract) The shift from conduction to the respiratory portion occurs at the terminal/respiratory bronchiole interface. There is some gas exchange here, but the majority occurs in the alveoli proper: alveoli proper: Site of gas exchange with adjacent alveolar capillaries. Alveolar epithelial cell types: simple squamous pneumocytes (type i) : simple squamous epithelium with tight junctions between cells. This is the site of gas exchange: cuboidal pneumocytes (type ii): interspersed among the type i pneumocytes.
