3.3 The Respiratory System - 3.3 THE RESPIRATORY SYSTEM...

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3.3 THE RESPIRATORY SYSTEM Components Airways:  function in the transport of air  -nasal passages, larynx, trachea, bronchi, bronchioles Alveoli:  sites of gas exchange -bronchi and bronchioles: conduct air, warm and humidify, remove particles Acini:  the alveoli supplied by one bronchiole Respiratory Physiology Air Quality:  The respiratory system may be normal and functional, but if the oxygen levels are abnormally low, then  normal respiration will not occur Ventilation:  Many diseases prevent air from reaching the sites of gas exchange in the alveoli - obstructive lung diseases:  reduce airflow in the bronchi and bronchioles, due to contraction of smooth  muscle in the airways (bronchioconstriction) or plugging of airway lumens with mucous or leukocytes   - restrictive lung diseases:  damage the alveoli or the alveolar walls, reducing the functional volume and  elasticity of the lung   Gas exchange:  diseases may block gas exchange within the alveoli -oxygen diffuses from the inhaled air into the capillaries of the alveoli, and CO 2  diffuses from capillaries into the alveoli  where it is exhaled Type 1 pneumocytes:  flattened epithelial cells that make up the alveolar walls -have very little cytoplasm  -permit diffusion of gasses -very susceptible to injury Type 2 pneumocytes:  cuboidal cells that make up the alveolar walls -produce surfactant to lower surface tension and prevent collapse of alveoli -replace type 1 cells that have been injured -metabolism and detoxification (metabolize toxins) -if a patient has cardiac insufficiency or is very anemic because of a deficient of oxygen-bearing erythrocytes, then the  blood will be unable to carry sufficient oxygen to the tissues Pulmonary Defences -lung must remain sterile because bacteria induce inflammation which impedes gas exchange in the lung Mucociliary apparatus:  mucous that lines the nasal turbinates and the airways entrap particles and microbes, and  are propelled by ciliary beating to the pharynx where it is swallowed -larger particles will be trapped in the nasal passages -smaller particles will become trapped in the alveoli Alveolar macrophages:  normally reside within the alveoli and become activated in response to appropriate stimuli -engulf foreign particles, kill bacteria, and secrete cytokines that recruit neutrophils and additional  macrophages Mucosal secretions:
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