Structure and Function of the Pulmonary System Chapter

Structure and Function of the Pulmonary System Chapter 25 Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Structures of the Pulmonary System Airways Pulmonary circulation Chest wall Lungs Lobes (three on right, two on left) Ø Segments Ø Lobules Ø Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Structures of the Pulmonary System Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Structures of the Pulmonary System Conducting airways Ø Upper airways • Nasopharynx • Oropharynx Ø Larynx • Connects upper and lower airways Ø Lower airways • Trachea • Bronchi • Terminal bronchioles Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Structures of the Pulmonary System Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Bronchioles-”respiratory tree” Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Structures of the Pulmonary System Gas-exchange airways Ø Respiratory bronchioles Ø Alveolar ducts Ø Alveoli • Epithelial cells Type I alveolar cells – Alveolar structure Type II alveolar cells – Surfactant production Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Structures of the Pulmonary System Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

CO 2 & O 2 – alveolar exchange Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Structures of the Pulmonary System Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Pulmonary and Bronchial Circulation Pulmonary circulation has a lower pressure than the systemic circulation One third of pulmonary vessels are filled with blood at any given time Pulmonary artery divides and enters the lung at the hilus Each bronchus and bronchiole has an accompanying artery or arteriole Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Pulmonary and Bronchial Circulation Alveolocapillary membrane Ø Formed by the shared alveolar and capillary walls ØGas exchange occurs across this membrane Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Pulmonary and Bronchial Circulation Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Chest Wall and Pleura Chest wall Skin, ribs, and intercostal muscles Ø Thoracic cavity Ø Pleura Serous membrane Ø Parietal and visceral layers Ø Pleural space (cavity) Ø Pleural fluid Ø Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Thoracic Cavity Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Function of the Pulmonary System Ventilate the alveoli Diffuse gases into and out of the blood Perfuse the lungs so the body receives oxygen Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Function of the Pulmonary System Ventilation Ø Mechanical movement of gas or air into and out of the lungs Ø Minute volume • Ventilatory rate multiplied by the volume of air per breath Ø Alveolar ventilation Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Ventilation Neurochemical control Ø Respiratory center • Dorsal respiratory group • Ventral respiratory group • Pneumotaxic center • Apneustic center Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Ventilation Neurochemical control Ø Lung receptors • Irritant receptors • Stretch receptors • J receptors ØChemoreceptors • Central chemoreceptors • Peripheral chemoreceptors Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Neurochemical Respiratory Control Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Mechanics of Breathing Major and accessory muscles Ø Major muscles of inspiration • Diaphragm • External intercostals Ø Accessory muscles of inspiration • Sternocleidomastoid and scalene muscles Ø Accessory muscles of expiration • Abdominal and internal intercostal muscles Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Muscles of Ventilation Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Mechanics of Breathing Alveolar surface tension and ventilation Ø Function of surfactant Elastic properties of the lung and chest wall Elastic recoil Ø Compliance Ø Airway resistance Work of breathing Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Mechanics of Breathing Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

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Gas Transport Four steps Ventilation of the lungs Ø Diffusion of oxygen from the alveoli into the capillary blood Ø Perfusion of systemic capillaries with oxygenated blood Ø Diffusion of oxygen from systemic capillaries into the cells Ø Diffusion of CO 2 occurs in reverse order Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

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Louie’s Backyard Restaurant Key West Florida Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Measurement of Gas Pressure Barometric pressure ØPartial pressure of water vapor Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

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Measurement of Gas Pressure Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Gas Transport Distribution of ventilation and perfusion ØGravity and alveolar pressure ØVentilation-perfusion ratio(0. 8) Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Gas Transport Oxygen transport Ø Diffusion across the alveolocapillary membrane Ø Determinants of arterial oxygenation • Hemoglobin binding, oxygen saturation Ø Oxyhemoglobin association and dissociation • Oxyhemoglobin dissociation curve • Bohr effect Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Measurement of Gas Pressure Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Gas Transport Carbon dioxide transport ØDissolved in plasma ØBicarbonate(HCO 3) ØCarbamino compounds (hemaglobin) Haldane effect Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Carbon Dioxide Transport Dissolved in plasma-Pco 2 Ø Arterial -5% Ø Venous-10% Bicarbonate-HCO 3 Ø Arterial-90% Ø Venous-60% Carbamino compounds-Hb Ø Arterial-5% Ø Venous-30% Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Control of Pulmonary Circulation Hypoxic pulmonary vasoconstriction Ø Ø Caused by low alveolar PO 2 Blood is shunted to other, well-ventilated portions of the lungs • Provides better ventilation and perfusion matching • If hypoxia affects all segments of the lungs, the vasoconstriction can result in pulmonary Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Control of Pulmonary Circulation Acidemia also causes pulmonary artery constriction Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Tests of Pulmonary Function Spirometry Diffusion capacity Residual volume Functional reserve capacity (FRC) Total lung capacity Arterial blood gas analysis Chest radiographs Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Aging and the Pulmonary System Loss of elastic recoil Stiffening of the chest wall Alterations in gas exchange Increases in flow resistance Decreased exercise tolerance Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.

Aging and the Pulmonary System Elsevier items and derived items © 2008 by Mosby, Inc. , an affiliate of Elsevier Inc. Some material was previously published.