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Charlotte Youngson

22 -The Respiratory System Pre-lecture questions 1. List the correct order of structures through which air moves from when it enters the body at the mouth and nose to the alveoli in the lungs. 23 level of branching. Trachia. Bronchi. Bronchioles. Respiratori bronchioles. Aveoli. 2. Write the formulae for Boyle’s Law and Henry’s Law and describe in words the important principle described by each. Pressure=1/volume (pressure goes up, volume goes down) 3. Draw an oxyhemoglobin dissociation curve. What information does this curve provide? S shaped curve. 98% of oxygen is on hemoglobin. Only 20% unloaded at rest. In excersise graph shirts to right. Respiration • Involves both the respiratory and the circulatory systems • Four processes that supply the body with O and 2ispose of CO 2 • Pulmonary ventilation (breathing): movement of air into and out of the lungs Respiratory • External respiration: O 2nd CO 2 System exchange between the lungs and the blood • Transport: O a2d CO 2 Circulatory in the blood System • Internal respiration: O 2nd CO 2 exchange between systemic blood vessels and tissues *NOTES • When volume is big, pressure is low. • Its simple diffusion due to pressure • When diaphragm contracts it pulls down Functional Anatomy • Respiratory zone: site of gas exchange • Microscopic structures: respiratory bronchioles, alveolar ducts, and alveoli • Conducting zone: conduits to gas exchange sites • Includes all other respiratory structures • Respiratory muscles: diaphragm and other muscles that promote ventilation Larynx • Attaches to the hyoid bone and opens into the laryngopharynx • Continuous with the trachea • Functions 1. Provides a patent airway 2. Routes air and food into proper channels 3. Voice production Trachea • Windpipe: from the larynx into the mediastinum • Wall composed of three layers 1. Mucosa: ciliated pseudostratified epithelium with goblet cells 2. Submucosa: connective tissue with seromucous glands 3. Adventitia: outermost layer made of connective tissue that encases the C-shaped rings of hyaline cartilage Bronchi and Subdivisions • Air passages undergo 23 orders of branching • Branching pattern called the bronchial (respiratory) tree Conducting Zone Structures • Trachea  right and left main (primary) bronchi • Each main bronchus enters the hilum of one lung • From bronchi through bronchioles, structural changes occur • Cartilage rings give way to plates; cartilage is absent from bronchioles • Epithelium changes from pseudostratified columnar to cuboidal; cilia and goblet cells become sparse • Relative amount of smooth muscle increases Respiratory Zone • Respiratory bronchioles, alveolar ducts, alveolar sacs (clusters of alveoli) • ~300 million alveoli account for most of the lungs’ volume and are the main site for gas exchange Alveoli • Surrounded by fine elastic fibers • Contain open pores that • Connect adjacent alveoli • Allow air pressure throughout the lung to be equalized • House alveolar macrophages that keep alveolar surfaces sterile • Gas exchange happens in aveoli *NOTES • surfactant-secreting- break down hydrogen bonding. Like detergent to inflate wet balloon. • Macrophage • Blood came ftom right ventricle. Pleurae • Thin, double-layered serosa • Parietal pleura on thoracic wall and superior face of diaphragm • Visceral pleura on external lung surface • Pleural fluid fills the slitlike pleural cavity • Provides lubrication and surface tension Mechanics of Breathing • Pulmonary ventilation consists of two phases 1. Inspiration: gases flow into the lungs 2. Expiration: gases exit the lungs Pressure Relationships in the Thoracic Cavity • Atmospheric pressure (P ) atm • Pressure exerted by the air surrounding the body • 760 mm Hg at sea level • Respiratory pressures are described relative to P atm • Negative respiratory pressure is less than P atm • Positive respiratory pressure is greater than P atm • Zero respiratory pressure = P atm *NOTES • We r at c level • We only about O. not N. • We don’t want CO2. plants love it. • We have 760. so for us breath in, our pressure in lungs should be lower. To breeth out pressure in lungs should be higher then in the air. Intrapulmonary Pressure • Intrapulmonary (intra-alveolar) pressure (P ) pul • Pressure in the alveoli • Fluctuates with breathing • Always eventually equalizes with P atm Intrapleural Pressure • Intrapleural pressure (P ): ip • Pressure in the pleural cavity • Fluctuates with breathing • Always a negative pressure (
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