Chapter 22: Respiratory System

Copyright © 2007 by Saunders, an imprint of Elsevier Inc. 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. Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Structure: Organs of the Respiratory System Upper respiratory tract: respiratory organs located outside chest cavity Lower respiratory tract: organs located inside the chest cavity Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Structure: Organs of the Respiratory System (cont’d.) Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Upper Respiratory System Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Upper Respiratory System (cont’d.) Nose: external portion forms part of the face Nasal cavities: internal portion of the nose Nasal septum: partition between right and left halves of the nasal cavities Nostrils: two openings in the nasal cavities through which air enters; also called nares Olfactory organs: receptor cells for the sense of smell Nasal conchae: three bony projections on the lateral walls of the nasal cavities Paranasal sinuses: drainage openings Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Upper Respiratory System (cont’d.) Pharynx: conducts food to esophagus and air to larynx Nasopharynx: upper Oropharynx: middle Laryngopharynx: lower Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Upper Respiratory System (cont’d.) Larynx: voicebox; triangular structure of cartilage, muscles, and ligaments Thyroid cartilage Epiglottis Vocal cords Glottis Three functions: Passageway for air Produce sound Prevents objects from entering breathing structures Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Upper Respiratory System (cont’d.) Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Upper Respiratory System (cont’d.) Trachea: windpipe; splits into left and right bronchi in thoracic cavity Carina: point at which trachea splits at the manubriosternal junction Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Lower Respiratory System Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Lower Respiratory System (cont’d.) Bronchial tree: Bronchi Bronchioles Alveoli Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Lower Respiratory System (cont’d.) Bronchi: formed from lower trachea dividing into two parts, left and right bronchi Primary bronchi: enter lungs at the hilus, branch into secondary bronchi Secondary bronchi: branch into smaller tertiary bronchi Tertiary bronchi Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Lower Respiratory System (cont’d.) Bronchioles: smaller tubes formed from repeated division of bronchi; regulate flow of air to the alveoli Alveolar ducts: formed from the division of bronchioles Alveoli: small grape-like structures at the end of the alveolar ducts; tiny air sacs Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Lower Respiratory System (cont’d.) Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Lower Respiratory System (cont’d.) Lungs: large, soft, cone-shaped organs; occupy most of the thoracic cavity Right lung: three lobes Superior Middle Inferior Left lung: two lobes Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Lower Respiratory System (cont’d.) Pleura: continuous serous membrane Visceral pleura Parietal pleura Pleural cavity: space between visceral pleura and parietal pleura Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Lower Respiratory System (cont’d.) Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Collapsed and Expanded Lungs Lungs collapse because of: Elastic recoil Surface tension Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Collapsed and Expanded Lungs (cont’d.) Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Collapsed and Expanded Lungs (cont’d.) Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Collapsed and Expanded Lungs (cont’d.) Lungs expand due to negative pressure within the intrapleural space Atmospheric pressure Intrapulmonic pressure Intrapleural pressure Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Collapsed and Expanded Lungs (cont’d.) Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Copyright © 2007 by Saunders, an imprint of Elsevier Inc. Lesson 22.2 Objectives Describe the relationship of Boyle’s law to ventilation. Explain how respiratory muscles affect thoracic volume. List three conditions that make the alveoli well-suited for the exchange of oxygen and carbon dioxide. Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Lesson 22.2 Objectives (cont’d.) List lung volumes and capacities Explain the neural and chemical control of respiration. Describe common variations and abnormalities of breathing. Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Copyright © 2007 by Saunders, an imprint of Elsevier Inc. Respiratory Function Three steps of respiration: Ventilation, or breathing Exchange of oxygen and carbon dioxide Transport of oxygen and carbon dioxide by the blood Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Respiratory Function (cont’d.) Ventilation: breathing; two phases are inhalation and exhalation Respiratory cycle: one inhalation and one exhalation Boyle’s law: relationship between pressure and volume Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Respiratory Function (cont’d.) Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Respiratory Function (cont’d.) Boyle’s law and ventilation: Inhalation is due to an increase in the thoracic and lung volumes As lung volume increases, intrapulmonic pressure decreases, causing air to move into the lungs (inhalation) Exhalation is due to a decrease in thoracic and lung volumes As lung volume decreases, intrapulmonic pressure increases and air moves out of the lungs (exhalation) Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Respiratory Function (cont’d.) Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Respiratory Function (cont’d.) Respiratory muscles: contract and relax to change thoracic volume Diaphragm: dome-shaped muscle that forms the floor of the thoracic cavity; chief muscle of inspiration Intercostal muscles: located between the ribs Accessory muscles of respiration: used to move the rib cage farther during exertion and for forced exhalation Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Respiratory Function (cont’d.) Motor nerves that supply the respiratory muscles: Phrenic nerve Intercostal nerves Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Respiratory Function (cont’d.) Three conditions make alveoli well suited for gas exchange: Large surface area Thin alveolar and pulmonary capillary walls Short distance between the alveoli and pulmonary capillaries Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Respiratory Function (cont’d.) Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Respiratory Function (cont’d.) Partial pressure: amount of pressure each gas contributes to the total pressure Oxyhemoglobin: molecule formed from oxygen and hemoglobin bond Carbaminohemoglobin: molecule formed from carbon dioxide and hemoglobin bond Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Respiratory Function (cont’d.) Pulmonary volumes: Tidal volume: 500 ml Inspiratory reserve volume: 3000 ml Expiratory reserve volume: 1100 ml Residual volume: 1200 ml Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Respiratory Function (cont’d.) Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Respiratory Function (cont’d.) Pulmonary capacities: Vital capacity: 4600 ml Functional residual capacity: 2300 ml Total lung capacity: 5800 ml Anatomical dead space: 150 ml Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Respiratory Function (cont’d.) Control of respiration Nervous mechanisms Brain stem: medulla oblongata (most important) and pons Higher centers: cerebral cortex and hypothalamus Chemical mechanisms detect changes in blood concentrations of CO2 and H+ Central chemoreceptors Peripheral chemoreceptors: aortic and carotid bodies Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Respiratory Function (cont’d.) Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Respiratory Function (cont’d.) Variations of respiration: Normal respiratory rate: body is at rest Increased respiratory rate: associated with exercise, anxiety, increases in metabolic rate, and overstimulation of the respiratory center in the brain Decreased respiratory rate: associated with relaxation, decreases in metabolic rate, depression of the respiratory center in the brain Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Respiratory Function (cont’d.) Hyperventilation: increase in the rate and depth of respirations causing excess exhalation of carbon dioxide Hypoventilation: decrease in the amount of air entering the alveoli causing insufficient oxygen and excessive carbon dioxide levels in the blood Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Common Respiratory Terms Apnea: temporary cessation of breathing Dyspnea: difficult or labored breathing Tachypnea: rapid breathing Eupnea: normal, quiet breathing Orthopnea: difficulty in breathing that is relieved by a sitting-up position Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Common Respiratory Terms (cont’d.) Cheyne-Stokes respirations: irregular breathing pattern characterized by a series of shallow breaths that gradually increase in depth and rate Kussmaul breathing: increase in rate and depth of respiration stimulated by acidosis Cyanosis: bluish color of the skin or mucous membrane due to a low concentration of oxygen in the blood Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved.

Common Respiratory Terms (cont’d.) Hypoxia: abnormally low concentration of oxygen in the tissues Hypoxemia: abnormally low concentration of oxygen in the blood Hypercapnia: abnormally high concentration of carbon dioxide in the blood Hypocapnia: abnormally low concentration of carbon dioxide in the blood Copyright © 2007 by Saunders, an imprint of Elsevier Inc. All rights reserved.