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Lecture 15

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Michelle French

Lecture 15 Respiratory System  What are the functions of the respiratory system?  Exchange of gases between air and blood (Alveoli of the lungs)  Regulation of body pH  By regulating CO2 levels  Defense from inhaled pathogens/foreign particles  IgE  Vocalization  What structures make up the respiratory system?  Upper Respiratory System  Nasal Cavity  Air enters the system  Pharynx  Vocal chords  Lower Respiratory Tract  Trachea  splits into left and right bronchus  Bronchus  stem off into bronchioles  Bronchioles  further divide into alveolus  Alveolus  surrounded by blood capillaries, exchange of O2 and CO2 by diffusion  There is 22 divisions that lead to the alveolus  Respiratory Muscles  Inspiration Muscle  Diaphragm  External Intercostals (Ribs)  Scalenes  For forceful breathing  Sternocleido-mastoid  For forceful breathing  Expiration Muscle  Internal Intercostals (Ribs)  For forceful breathing  Abdominal Muscles  For forceful breathing  Pleural Sacs enclose the lungs  Visceral and Parietal  Pleural cavity is filled with fluid, which aids in reducing friction during breathing  Surface tension of the pleural fluid also leads to close apposition of the lung surfaces with the chest wall. This relationship allows for greater inflation of the alveoli during respiration  Airways  Larynx (vocal chords)  Trachea (rings help prevent collapse)  Primary Bronchus  Secondary Bronchus  Bronchiole  Alveoli  Warm air to 37 degree celsius  Humidify to 100%  Filter (nose and cilia)  Filtering action of cilia that line airways  Two cell types  Goblet cells secrete mucus  Epithelial cells that project cilia  Mucus layer traps inhaled particles  Watery saline layer allows cilia to push mucus towards pharynx  Pharynx is the passage way between larynx and esophagus, you can either swallow the mucus, or spit it out  Immune cells secrete antibodies disabling pathogens  The primary Lobule  Region of gas exchange  Approx. 300 million alveoli, each about 300 μm in diameter  Total cross-sectional area is very large, about 180 cm2, and air velocity virtually zero  Alveoli  Richly supplied with blood through capillaries surrounding the alveoli. Capillaries are fed by the pulmonary artery and are emptied by the pulmonary vein  Type I alveolar cell  1 cell thick, most abundant alveolar cells  Make up the alveolar sacs 
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