Transcript Chapter 19
PowerPoint Lecture Outlines to accompany Hole’s Human Anatomy and Physiology Eleventh Edition Shier w Butler w Lewis Chapter 19 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 1 Chapter 19 Respiratory System Respiration is the process of exchanging gases between the atmosphere and body cells. Consists of the following events: • ventilation • external respiration • transport • internal respiration • cellular respiration 2 Organs of the Respiratory System 3 Organs of the Respiratory System 4 Upper Respiratory Tract 5 Mucous in Respiratory Tract Cilia move mucus and trapped particles from the nasal cavity to the pharynx 6 Sinuses Air-filled spaces in maxillary, frontal, ethmoid, and sphenoid bones 7 Pharynx 8 Larynx 9 Vocal Cords 10 Trachea 11 Tracheostomy Performed to allow air to bypass an obstruction within the larynx 12 Bronchial Tree 13 Alveoli 14 Diffusion Across Respiratory Membrane 15 Lungs 16 Transverse Section of Lungs 17 Breathing Mechanism • Breathing or ventilation is the movement of air from outside the body into the bronchial tree and alveoli • air movements of inspiration and expiration • changes in the size of the thoracic cavity due to changes in pressure 18 Inspiration • Moving the plunger of a syringe causes air to move in or out • Air movements in and out of the lungs occur in much the same way 19 Lungs at Rest When lungs are at rest, the pressure on the inside of the lungs is equal to the pressure on the outside of the thorax 20 Inspiration • Intra-alveolar pressure decreases to about 758mm Hg as the thoracic cavity enlarges • Atmospheric pressure forces air into the airways 21 Inspiration Shape of thorax at end of normal inspiration Shape of thorax at end of maximal inspiration aided by contraction of sternocleidomastoid and pectoralis minor muscles 22 Major Events in Inspiration 23 Expiration • due to elastic recoil of the lung tissues and abdominal organs 24 Maximal Expiration • contraction of abdominal wall muscles • contraction of posterior internal intercostal muscles 25 Major Events in Expiration 26 Respiratory Volumes and Capacities 27 Respiratory Volumes and Capacities 28 Alveolar Ventilation minute ventilation • tidal volume multiplied by breathing rate • amount of air that is moved into the respiratory passageways alveolar ventilation rate • major factor affecting concentrations of oxygen and carbon dioxide in the alveoli • volume of air that reaches alveoli • tidal volume minus physiologic dead space then multiplied by breathing rate 29 Nonrespiratory Air Movements 30 Respiratory Center 31 Respiratory Center 32 Factors Affecting Breathing Decreased blood oxygen concentration stimulates peripheral chemoreceptors in the carotid and aortic bodies 33 Factors Affecting Breathing • motor impulses travel from the respiratory center to the diaphragm and external intercostal muscles • contraction of these muscles causes lungs to expand • expansion stimulates stretch receptors in the lungs • inhibitory impulses from receptors to respiratory center prevent overinflation of lungs 34 Factors Affecting Breathing 35 Alveoli • gas exchanges between the air and blood occur within the alveoli • alveolar pores allow air to pass from one alveolus to another 36 Respiratory Membrane • consists of the walls of the alveolus and the capillary 37 Diffusion Through Respiratory Membrane Gases are exchanged between alveolar air and capillary blood because of differences in partial pressure 38 Oxygen Transport • Most oxygen binds to hemoglobin to form oxyhemoglobin • Oxyhemoglobin releases oxygen in the regions of body cells • Much oxygen is still bound to hemoglobin in the venous blood 39 Oxygen Release Amount of oxygen released from oxyhemoglobin increases as • partial pressure of carbon dioxide increases • the blood pH decreases • blood temperature increases 40 Carbon Dioxide Transport • dissolved in plasma • combined with hemoglobin • in the form of bicarbonate ions 41 Chloride Shift • bicarbonate ions diffuse out RBCs • chloride ions from plasma diffuse into RBCs • electrical balance is maintained 42 Carbon Dioxide in Lungs 43 Gases Transported in Blood 44 Life-Span Changes • reflect accumulation of environmental influences • reflect the effects of aging in other organ systems • cilia less active • mucous thickens • swallowing, gagging, and coughing reflexes slow • macrophages in lungs lose efficiency • increased susceptibility to respiratory infections • “barrel chest” may develop • bronchial walls thin and collapse • dead space increases 45 Clinical Application The Effects of Cigarette Smoking on the Respiratory System • cilia disappear • excess mucus produced • lung congestion increases lung infections • lining of bronchioles thicken • bronchioles lose elasticity • emphysema fifteen times more common • lung cancer more common • much damage repaired when smoking stops 46