Ch. 34 Structure of Function of Pulmonary System.pdf

Ch. 34 Structure of Function of Pulmonary System.pdf - Ch...

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Connects the larynx to the bronchi( the conducting airways of the lungs) i. Trachea is supported by U-shaped cartilage a. very sensitive and when stimulated (coughing and airway narrowing) i. The trachea divides into the two main airways --> bronchi at the carina b. Left bronchus branches from trachea about 45 degree angle, Right more vertical ==> more aspiration and foreign particles in the RIGHT c. branch into lobar bronchi --> segmental --> subsegmental bronchi --> terminal bronchioles (16th division) i. decreased velocity of airflow into the gas-exchange portion of the lung 1) allows for optimal gas diffusion. 2) These multiple divisions results in ii. Hila (“roots” of the lungs): where bronchi enters with the pulmonary blood and lymphatic vessels. d. Large bronchi (approx. 10th division) [connective tissue with cartilage] i. Submucosal glands of bronchial lining secretes mucus too, "blanket" that covers the bronchial epithelium 1) Biochemical mediators released early in inflammation also play a part in antibody-mediated hypersensitivity reactions (ex. Asthma) --> bronchial smooth muscle constrict i) If foreign particles/ microorgaisms not expelled --> inflammatory response & antibodies a) Ciliated epithelial cells: beat mucous blanket toward trachea and pharynx -->swallowed or expectorated 2) Cilliated and goblet cells become more sparse and smooth muscle and connective tissue layers thin toward the terminal bronchioles 3) Epithelial lining: single-celled exocrine glands: mucus secreting goblet cells and ciliated cells ii. 3 layers of bronchial walls: epithelial lining, a smooth muscle layer, a connective tissue layer e. Structures of the Pulmonary System 1. Very thin bronchiole walls (a layer of cilia and goblet cells, little smooth muscle fiber, and elastic connective tissue laye r) i. Respiratory bronchioles: 16th-23rd divisions with increasing # of alveoli a. Alveoli : the primary gas-exchange units of the lung i. Collateral ventilation and even distribution of air among the alveoli 1) Pores of Kohn: tiny passages for some air to pass through the septa from alveolus to alveolus ii. Type I alveolar cells: provide structure (primary surface area) 1) lipoprotein that coats the inner alveolus i) Facilitates its expansion during inspiration ii) Lowers alveolar surface tension at end-expiration iii) Prevents lung collapse iv) Control of lung inflammation and innate and adaptive immunity v) Surfactant : a) Type II alveolar cells: secrete SURFACTANT 2) 2 Major types of epithelial cells in alveolus iii. Ingest foreign material that reaches the alveolus and remove through the lymphatics a) Alveoli mononuclear phagocytes are called : Alveolar macrophages 1) Components of inflammation and immunity iv. Alveolar ducts --> Alveolar sacs --> Alveoli b. Gas-Exchange Airways [Respiratory bronchioles, alveolar ducts, and alveoli = Acinus ] 2.
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