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CHAPTER 25 Respiratory System

CHAPTER 25 Respiratory System - CHAPTER 25 RESPIRATORY...

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CHAPTER 25 RESPIRATORY SYSTEM Respiratory system exchanges gas b/w atm and blood; cardiovascular system transports gases b/w lungs and cells. (partnership) I. GENERAL ORGANIZATION AND FUNCTIONS OF THE RESPIRATORY SYSTEM A. Basic description i. Anatomically—consists of upper and lower respiratory tracts ii. Functionally—divided into conducting and respiratory portions 1. Conducting portion —transports air A. Consists of nose, nasal cavity, pharynx (of upper resp. tract), larynx, trachea, and progressively smaller airways (from the primary bronchi to terminal bronchioles) of the lower resp. tract. 2. Respiratory portion —where gas exchange with blood occurs A. Includes respiratory bronchioles, alveolar ducts (small airways), alveoli (air sacs in the lower resp. tract). B. Respiratory System Functions (5) i. (Pulmonary ventilation (breathing): inhalation/inspiration and exhalation/expiration) ii. Gas exchange (2 types) 1. External Respiration —b/w atm and blood A. Atm O 2 lungs blood B. CO 2 in blood lungs exhaled to atm (happens at the same time as 0 2 ) 2. Internal Respiration —b/w blood and cells A. Blood transports O 2 from lungs cells B. Blood transports CO 2 from cells lungs iii. Gas Conditioning 1. As gases pass through the airways, they’re “conditioned” : A. Warmed to body temp B. Humidified (moistiened) C. Cleaned of particles. (via contact w the mucous covering the respiratory epithelium) 2. The pathways of the nasal cavity and paranasal sinuses condition the air. (twisted pathway makes the air turbulent and remain in the tube for a longer time). iv. Sound Production 1. Speech/singing when air is forced out of lungs and moves through the larynx 2. Other structures that aid sound production: nasal cavity, paranasal sinuses, teeth, lips, tongue v. Olfaction 1. Superior region of the nasal cavity is covered w olfactory epithelium (has receptors for smell that are stimulated when airborne molecules are inhaled and dissolved in the mucous covering)
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vi. Defense 1. Both the structures of the respiratory system and some of the cells of the respiratory epithelium protect against infection by airborne molecules. 2. The entrance to the respiratory system (nose) is inferiorly directed, lined with coarse hairs, and has twisted tubes to prevent large particles, microorganisms, and insects from entering. 3. Goblet cells (secrete mucin) dispersed throughout the pseudostratified ciliated columnar epithelium that lines most of the upper resp. tract. 4. Mucous glands in the lamina propria (deep to the epithelium) contribute to the layer of mucous covering the epithelium and keep it from drying out. A. Mucous glands also secrete lysozome—enzyme that defends against inhaled bacteria. 5. Layer of mucous traps inhaled things, and if we’re exposed to irritants, mucin production increases.
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