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The Human Body in Health and Illness, 4th edition Barbara Herlihy Chapter 22: Respiratory System LESSON 22-1 OBJECTIVES Describe the structure and functions of the organs of the respiratory system. Trace the movement of air from the nostrils to the alveoli. Describe the role of pulmonary surfactants. 2 COPYRIGHT © 2011, 2007 BY SAUNDERS, AN IMPRINT OF ALL RIGHTS RESERVED. ELSEVIER INC. STRUCTURE: ORGANS OF THE RESPIRATORY SYSTEM Respiratory System divided into two sections: •Upper respiratory tract: Organs located outside the chest •Lower respiratory tract: Organs located inside the chest 3 COPYRIGHT © 2011, 2007 BY SAUNDERS, AN IMPRINT OF ALL RIGHTS RESERVED. ELSEVIER INC. UPPER RESPIRATORY SYSTEM Nose and nasal cavities Pharynx Nasopharynx Oropharynx Laryngopharynx Larynx Vocal cords Upper trachea Cartilaginous rings: rings of the trachea prevent its collapse, helping maintain an open airway 4 FUNCTIONS OF UPPER RESPIRATORY STRUCTURES •Nose and nasal passages: Warm, moisturize, and conduct air •Pharynx (throat): Conducts air to lower structures •Larynx (voice box): Vibrates vocal cords, produces sound, and conducts air to lower structures •Trachea (windpipe): Conducts air to right bronchus and left bronchus •WHY DO WE HAVE A RIGHT BRONCHUS AND A LEFT BRONCHUS? 5 LOWER RESPIRATORY SYSTEM Lower trachea Bronchi Bronchioles Alveoli Lungs Pleural membranes Muscles of respiration 6 BRONCHIAL TREE Right and left bronchi Cartilaginous rings Carina: a cartilaginous ridge within the trachea Bronchioles Smooth muscle Alveoli Single layered membrane Bronchial Tree THE MUCOUS MEMBRANE OF THE CARINA IS THE MOST SENSITIVE AREA OF THE TRACHEA AND LARYNX FOR TRIGGERING A COUGH REFLEX. WIDENING AND DISTORTION OF THE CARINA IS A SERIOUS SIGN BECAUSE IT USUALLY INDICATES CARCINOMA OF THE LYMPH NODES AROUND THE REGION WHERE THE TRACHEA DIVIDES. 8 COPYRIGHT © 2011, 2007 BY SAUNDERS, AN IMPRINT OF ALL RIGHTS RESERVED. ELSEVIER INC. BRONCHIAL TREE: FUNCTIONS Bronchi: Conduct air to bronchioles Bronchioles: Smooth muscle determines diameter, regulates air flow to the alveoli Alveoli: Small grapelike structures; air sacs that exchange O2 and CO2 with blood in pulmonary circulation 9 GAS EXCHANGE AND THE ALVEOLI O2 moves from alveoli into pulmonary capillaries. CO2 moves from pulmonary capillaries into alveoli. 10 LUNGS •Large, soft, cone-shaped organs; contain structures of lower respiratory tract •Apex (top), base (bottom) •Right lung: Three lobes –Superior –Middle –Inferior •Left lung: Two lobes –Superior –Inferior 11 COPYRIGHT © 2011, 2007 BY SAUNDERS, AN IMPRINT OF ELSEVIER INC. ALL RIGHTS RESERVED. THREE STEPS OF RESPIRATION Ventilation Inhalation (inspiration) Exhalation (expiration) Respiratory cycle = one inhalation + one exhalation Exchange of O2 and CO2 At the lungs (alveoli) At the tissue level Transport of O 12 2 and CO2 by the blood BOYLE’S LAW: INHALATION Respiratory muscles contract to increase thoracic volume. As thoracic volume increases, intrathoracic pressure decreases. Air moves in. 13 COPYRIGHT © 2011, 2007 BY SAUNDERS, AN IMPRINT OF ALL RIGHTS RESERVED. ELSEVIER INC. BOYLE’S LAW: EXHALATION Respiratory muscles relax to decrease thoracic volume. As volume decreases, intrathoracic pressure (P2) increases. Air moves out. 14 RESPIRATORY MUSCLES AND NERVES Diaphragm Innervated (supplied with nerves) by phrenic nerve (C3C5); if this nerve is severed, ventilation stops Intercostal muscles Innervated by intercostal nerves 15 GAS EXCHANGE: LUNGS AND TISSUE Lungs O2 moves into blood from alveoli. CO2 moves into alveoli from blood. Tissue O2 moves from blood to tissue. CO2 moves from tissue to blood. 16 CONTROL OF RESPIRATION Ner vous Chemical Medulla oblongata: fires Pco2 (carbon dioxide) major regulator. Chemoreceptors: regulate the rate and depth of respiration rhythmically and stimulates the phrenic and intercostal nerves • primary control center for respirations • Inspiratory neurons • Expiratory neurons Central (CNS) Peripheral: Carotid bodies (The • Pons 17 carotid body functions as a sensor: it responds to a stimulus, primarily O2 partial pressure), aortic bodies (It measures changes in blood pressure and the composition of arterial blood flowing past it, including the partial pressures of oxygen and carbon dioxide) COMMON RESPIRATORY TERMS Eupnea: Normal, quiet breathing Apnea: Temporary cessation of breathing Dyspnea: Difficult or labored breathing Tachypnea: Rapid breathing Bradypnea: Abnormally slow breathing Orthopnea: Difficulty in breathing relieved by sitting up 18 COMMON RESPIRATORY TERMS (CONT’D.) Hyperventilation: Increase in rate and depth Hypoventilation: Decrease in rate and depth Hypoxemia: Abnormally low concentration of O 2 in the blood Hypercapnia: Abnormally high concentration of CO2 in the blood Hypocapnia: Abnormally low concentration of CO2 in the blood 19 F.Y.I • The alveoli form the terminal end of the respiratory tract. The purpose of the entire respiratory system is to move air to the alveoli so that gas exchange can occur with the capillaries. • A tracheoesophageal (TE) fistula is an opening between the trachea and esophagus found in some newborns. It must be corrected with surgery to prevent aspiration, severe respiratory distress, and death. 20