The Human Body in Health and Illness, 4 th edition Barbara Herlihy Chapter 22: Respiratory System

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. LESSON 22-1 OBJECTIVES 2 COPYRIGHT © 2011, 2007 BY SAUNDERS, AN IMPRINT OF ELSEVIER INC. ALL RIGHTS RESERVED.

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 ELSEVIER INC. ALL RIGHTS RESERVED. STRUCTURE: ORGANS OF THE 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 UPPER RESPIRATORY SYSTEM

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? FUNCTIONS OF UPPER RESPIRATORY STRUCTURES 5

Lower trachea Bronchi Bronchioles Alveoli Lungs Pleural membranes Muscles of respiration 6 LOWER RESPIRATORY SYSTEM

Right and left bronchi Cartilaginous rings Carina: a cartilaginous ridge within the trachea Bronchioles Smooth muscle Alveoli Single layered membrane Bronchial Tree BRONCHIAL TREE

COPYRIGHT © 2011, 2007 BY SAUNDERS, AN IMPRINT OF ELSEVIER INC. ALL RIGHTS RESERVED. 8 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.

Bronchi: Conduct air to bronchioles Bronchioles: Smooth muscle determines diameter, regulates air flow to the alveoli Alveoli: Small grapelike structures; air sacs that exchange O 2 and CO 2 with blood in pulmonary circulation 9 BRONCHIAL TREE: FUNCTIONS

O 2 moves from alveoli into pulmonary capillaries. CO 2 moves from pulmonary capillaries into alveoli. 10 GAS EXCHANGE AND THE ALVEOLI

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 LUNGS 11 COPYRIGHT © 2011, 2007 BY SAUNDERS, AN IMPRINT OF ELSEVIER INC. ALL RIGHTS RESERVED.

Ventilation Inhalation (inspiration) Exhalation (expiration) Respiratory cycle = one inhalation + one exhalation Exchange of O 2 and CO 2 At the lungs (alveoli) At the tissue level Transport of O 2 and CO 2 by the blood THREE STEPS OF RESPIRATION 12

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 ELSEVIER INC. ALL RIGHTS RESERVED. BOYLE’S LAW: INHALATION

Respiratory muscles relax to decrease thoracic volume. As volume decreases, intrathoracic pressure (P2) increases. Air moves out. 14 BOYLE’S LAW: EXHALATION

Diaphragm Innervated (supplied with nerves) by phrenic nerve (C3- C5); if this nerve is severed, ventilation stops Intercostal muscles Innervated by intercostal nerves RESPIRATORY MUSCLES AND NERVES 15

Lungs O 2 moves into blood from alveoli. CO 2 moves into alveoli from blood. Tissue O 2 moves from blood to tissue. CO 2 moves from tissue to blood. 16 GAS EXCHANGE: LUNGS AND TISSUE

Medulla oblongata: fires rhythmically and stimulates the phrenic and intercostal nerves primary control center for respirations Inspiratory neurons Expiratory neurons Pons Pco2 (carbon dioxide) major regulator. Chemoreceptors: regulate the rate and depth of respiration Central (CNS) Peripheral : Carotid bodies (The 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) Nervous Chemical 17 CONTROL OF RESPIRATION

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 COMMON RESPIRATORY TERMS 18

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 CO 2 in the blood Hypocapnia: Abnormally low concentration of CO 2 in the blood COMMON RESPIRATORY TERMS (CONT’D.) 19

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. F.Y.I 20