Pulmonary Structure and Function Chapter 12 Pulmonary Structure and Function Copyright © 2007 Lippincott Williams & Wilkins. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition
Anatomy of Ventilation Pulmonary ventilation Process of air moving in and out of lungs Anatomy Trachea Bronchi Bronchioles Alveoli Copyright © 2007 Lippincott Williams & Wilkins. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition
Copyright © 2007 Lippincott Williams & Wilkins. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition
The Lungs Provide a large surface area (50 − 100 m2) Highly vascularized to allow for gas exchange Copyright © 2007 Lippincott Williams & Wilkins. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition
The Alveoli The lungs contain 600 million membranous sacs called alveoli. Characteristics of alveoli Elastic Thin walled Very small blood–gas barrier Copyright © 2007 Lippincott Williams & Wilkins. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition
Copyright © 2007 Lippincott Williams & Wilkins. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition
The Alveoli Pores of Kohn allow for even dispersion of surfactant. Surfactant decreases surface tension. Pores also allow for gas interchange between alveoli. Copyright © 2007 Lippincott Williams & Wilkins. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition
Mechanics of Ventilation Conducting zone (anatomic dead space) Trachea Bronchioles Respiratory zone Respiratory bronchioles Alveolar ducts Alveoli Copyright © 2007 Lippincott Williams & Wilkins. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition
Copyright © 2007 Lippincott Williams & Wilkins. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition
Fick’s Law Explains gas exchange through the alveolar membranes Gas diffuses through a tissue at a rate proportional to surface area and inversely proportional to its thickness. Copyright © 2007 Lippincott Williams & Wilkins. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition
Inspiration During inspiration Diaphragm contracts and flattens Chest cavity elongates and enlarges and air expands in lungs Intrapulmonic pressure decreases Air is sucked in through nose and mouth Copyright © 2007 Lippincott Williams & Wilkins. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition
Expiration During rest and light exercise, expiration is predominantly passive. Stretched lung tissue recoils Inspiratory muscles relax Air moves to atmosphere During strenuous exercise Internal intercostals and abdominal muscles assist Copyright © 2007 Lippincott Williams & Wilkins. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition
Surfactant Resistance to expansion of the lungs increases during inspiration due to surface tension on alveoli. Surfactant _ a lipoprotein mix of phospholipids, proteins, and Ca2+ produced by alveolar epithelial cells _ mixes with fluid around alveoli. Surfactant disrupts and lowers surface tension. Copyright © 2007 Lippincott Williams & Wilkins. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition
Lung Volumes & Capacities Are measured using a spirometer Lung volumes vary with Age Size (mainly stature) Gender Copyright © 2007 Lippincott Williams & Wilkins. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition
Static Lung Volumes TV: Tidal volume: 0.4 − 1.0 L air/breath IRV: Inspiratory reserve volume: 2.5 − 3.5 L ERV: Expiratory reserve volume: 1.0 − 1.5 L IRV and ERV decrease during exercise as TV increases FVC: Forced vital capacity: 3 − 5 L Copyright © 2007 Lippincott Williams & Wilkins. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition
Residual Lung Volume RLV averages 0.8 − 1.4 L RLV increases with age as lung elasticity decreases. Copyright © 2007 Lippincott Williams & Wilkins. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition
Total Lung Capacity RLV + FVC = TLC Copyright © 2007 Lippincott Williams & Wilkins. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition
Copyright © 2007 Lippincott Williams & Wilkins. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition
Dynamic Lung Volumes Dynamic ventilation depends upon Maximal FVC of lungs Velocity of flow Velocity of flow is influenced by lung compliance. Copyright © 2007 Lippincott Williams & Wilkins. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition
FEV-to-FVC Ratio FEV1/FVC indicates pulmonary airflow capacity. Healthy people average ~ 85% of FVC in 1 second. Obstructive diseases result in significant lower FEV1/FVC. Copyright © 2007 Lippincott Williams & Wilkins. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition
Maximum Voluntary Ventilation MVV evaluates ventilatory capacity with rapid and deep breathing for 15 seconds. MVV = 15 second volume × 4 MVV in healthy individuals averages 25% > ventilation than occurs during max exercise. Copyright © 2007 Lippincott Williams & Wilkins. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition
Exercise Implications Gender Differences in Static and Dynamic Lung Functional Measures Women have smaller lung function measures than men. Highly fit women must work harder to maintain adequate alveolar-to-arterial O2 exchange. Copyright © 2007 Lippincott Williams & Wilkins. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition
Lung Function, Aerobic Fitness, and Exercise Performance Little relationship exists among diverse lung volumes and capacities and exercise performance. Maximum exercise is not limited by ventilation. Copyright © 2007 Lippincott Williams & Wilkins. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition
Pulmonary Ventilation Volume of air moved into or out of total respiratory tract each minute Air volume that ventilates only alveolar chambers each minute Copyright © 2007 Lippincott Williams & Wilkins. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition
Minute Ventilation Minute ventilation Volume of air breathed each minute VE Minute ventilation increases dramatically during exercise. Values up to 200 L · min-1 have been reported. Average person ~ 100 L · min-1 Despite huge VE, TVs rarely exceed 60% VC. Copyright © 2007 Lippincott Williams & Wilkins. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition
Alveolar Ventilation Anatomic dead space Averages 150 − 200 mL Only ~ 350 mL of the 500 mL TV enters alveoli. Copyright © 2007 Lippincott Williams & Wilkins. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition
Dead Space vs. Tidal Volume Anatomic dead space increases as TV increases. Despite the increase in dead space, increases in TV result in more effective alveolar ventilation. Copyright © 2007 Lippincott Williams & Wilkins. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition
Ventilation−Perfusion Ratio Ratio of alveolar ventilation to pulmonary blood flow V/Q during light exercise ~ 0.8 V/Q during strenuous exercise may increase up to 5.0. Copyright © 2007 Lippincott Williams & Wilkins. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition
Physiologic Dead Space Occurs when there is either 1. Inadequate ventilation 2. Inadequate blood flow Copyright © 2007 Lippincott Williams & Wilkins. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition
Rate vs. Depth During exercise, both rate and depth of breathing increase. Initially, larger increases in depth occur. Followed by increases in rate and depth Copyright © 2007 Lippincott Williams & Wilkins. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition
Copyright © 2007 Lippincott Williams & Wilkins. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition
Hyperventilation An increase in pulmonary ventilation that exceeds O2 needs of metabolism Hyperventilation decreases PCO2. Copyright © 2007 Lippincott Williams & Wilkins. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition
Dyspnea Subjective distress in breathing During exercise, respiratory muscles may fatigue, resulting in shallow, ineffective breathing and increased dyspnea. Copyright © 2007 Lippincott Williams & Wilkins. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition
Valsalva Maneuver Closing the glottis following a full inspiration while maximally activating the expiratory muscles Causes increase in intrathoracic pressure Helps stabilize chest during lifting Copyright © 2007 Lippincott Williams & Wilkins. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition
Physiologic Consequences of Valsalva Maneuver An acute drop in BP may result from a prolonged Valsalva maneuver. Decreased venous return Decreased flow to brain Dizziness or fainting result Copyright © 2007 Lippincott Williams & Wilkins. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition
Respiratory Tract During Cold-Weather Exercise Cold ambient air is warmed as it passes through the conducting zone. Moisture is lost if the air is cold and dry. Contributes to Dehydration Dry mouth Irritation of respiratory passages Copyright © 2007 Lippincott Williams & Wilkins. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition
Postexercise Coughing Related to water loss and the drying of the throat Copyright © 2007 Lippincott Williams & Wilkins. McArdle, Katch, and Katch: Exercise Physiology: Energy, Nutrition, and Human Performance, Sixth Edition