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169 Ch 23_lecture_presentation

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169 Ch 23_lecture_presentation

  1. 1. © 2012 Pearson Education, Inc. PowerPoint® Lecture Presentations prepared by Jason LaPres Lone Star College—North Harris 23 The Respiratory System
  2. 2. © 2012 Pearson Education, Inc. An Introduction to the Respiratory System • Learning Outcomes • 23-1 Describe the primary functions of the respiratory system, and explain how the delicate respiratory exchange surfaces are protected from pathogens, debris, and other hazards. • 23-2 Identify the organs of the upper respiratory system, and describe their functions. • 23-3 Describe the structure of the larynx, and discuss its roles in normal breathing and in the production of sound.
  3. 3. © 2012 Pearson Education, Inc. An Introduction to the Respiratory System • Learning Outcomes • 23-4 Discuss the structure of the extrapulmonary airways. • 23-5 Describe the superficial anatomy of the lungs, the structure of a pulmonary lobule, and the functional anatomy of alveoli. • 23-6 Define and compare the processes of external respiration and internal respiration.
  4. 4. © 2012 Pearson Education, Inc. An Introduction to the Respiratory System • Learning Outcomes • 23-7 Summarize the physical principles governing the movement of air into the lungs, and describe the origins and actions of the muscles responsible for respiratory movements. • 23-8 Summarize the physical principles governing the diffusion of gases into and out of the blood and body tissues. • 23-9 Describe the structure and function of hemoglobin, and the transport of oxygen and carbon dioxide in the blood.
  5. 5. © 2012 Pearson Education, Inc. An Introduction to the Respiratory System • Learning Outcomes • 23-10 List the factors that influence respiration rate, and discuss reflex respiratory activity and the brain centers involved in the control of respiration. • 23-11 Describe age-related changes in the respiratory system. • 23-12 Give examples of interactions between the respiratory system and other organ systems studied so far.
  6. 6. © 2012 Pearson Education, Inc. An Introduction to the Respiratory System • The Respiratory System • Cells produce energy • For maintenance, growth, defense, and division • Through mechanisms that use oxygen and produce carbon dioxide
  7. 7. © 2012 Pearson Education, Inc. An Introduction to the Respiratory System • Oxygen • Is obtained from the air by diffusion across delicate exchange surfaces of lungs • Is carried to cells by the cardiovascular system, which also returns carbon dioxide to the lungs
  8. 8. © 2012 Pearson Education, Inc. 23-1 Components of the Respiratory System • Five Functions of the Respiratory System 1. Provides extensive gas exchange surface area between air and circulating blood 2. Moves air to and from exchange surfaces of lungs 3. Protects respiratory surfaces from outside environment 4. Produces sounds 5. Participates in olfactory sense
  9. 9. © 2012 Pearson Education, Inc. 23-1 Components of the Respiratory System • Organization of the Respiratory System • The respiratory system is divided into: • Upper respiratory system - above the larynx • Lower respiratory system - below the larynx
  10. 10. © 2012 Pearson Education, Inc. 23-1 Components of the Respiratory System • The Respiratory Tract • Consists of a conducting portion • From nasal cavity to terminal bronchioles • Consists of a respiratory portion • The respiratory bronchioles and alveoli • Alveoli • Are air-filled pockets within the lungs • Where all gas exchange takes place
  11. 11. © 2012 Pearson Education, Inc. Figure 23-1 The Components of the Respiratory System Nasal cavity Internal nares Pharynx Sphenoidal sinus Esophagus Clavicle UPPER RESPIRATORY SYSTEM LOWER RESPIRATORY SYSTEM RIGHT LUNG Bronchioles Bronchus Trachea Larynx Hyoid bone Tongue Nose Nasal conchae Ribs Diaphragm LEFT LUNG RIGHT LUNG Frontal sinus
  12. 12. © 2012 Pearson Education, Inc. 23-1 Components of the Respiratory System • The Respiratory Epithelium • For gases to exchange efficiently: • Alveoli walls must be very thin (<1 µm) • Surface area must be very great (about 35 times the surface area of the body)
  13. 13. © 2012 Pearson Education, Inc. 23-1 Components of the Respiratory System • The Respiratory Mucosa • Consists of: • An epithelial layer • An areolar layer called the lamina propria • Lines the conducting portion of respiratory system
  14. 14. © 2012 Pearson Education, Inc. 23-1 Components of the Respiratory System • The Lamina Propria • Underlying layer of areolar tissue that supports the respiratory epithelium • In the upper respiratory system, trachea, and bronchi • It contains mucous glands that secrete onto epithelial surface • In the conducting portion of lower respiratory system • It contains smooth muscle cells that encircle lumen of bronchioles
  15. 15. © 2012 Pearson Education, Inc. Figure 23-2a The Respiratory Epithelium of the Nasal Cavity and Conducting System A surface view of the epithelium. The cilia of the epithelial cells form a dense layer that resembles a shag carpet. The movement of these cilia propels mucus across the epithelial surface. Superficial view SEM × 1647
  16. 16. © 2012 Pearson Education, Inc. Figure 23-2b The Respiratory Epithelium of the Nasal Cavity and Conducting System Movement of mucus to pharynx Ciliated columnar epithelial cell Mucous cell Stem cell Mucus layer Lamina propria A diagrammatic view of the respiratory epithelium of the trachea, indicating the direction of mucus transport inferior to the pharynx.
  17. 17. © 2012 Pearson Education, Inc. Figure 23-2c The Respiratory Epithelium of the Nasal Cavity and Conducting System The sectional appearance of the respiratory epithelium, a pseudostratified ciliated columnar epithelium. Stem cell Basement membrane Mucous cell Nucleus of columnar epithelial cell Lamina propria Cilia
  18. 18. © 2012 Pearson Education, Inc. 23-1 Components of the Respiratory System • Structure of Respiratory Epithelium • Pseudostratified ciliated columnar epithelium with numerous mucous cells • Nasal cavity and superior portion of the pharynx • Stratified squamous epithelium • Inferior portions of the pharynx • Pseudostratified ciliated columnar epithelium • Superior portion of the lower respiratory system • Cuboidal epithelium with scattered cilia • Smaller bronchioles
  19. 19. © 2012 Pearson Education, Inc. 23-1 Components of the Respiratory System • Alveolar Epithelium • Is a very delicate, simple squamous epithelium • Contains scattered and specialized cells • Lines exchange surfaces of alveoli
  20. 20. © 2012 Pearson Education, Inc. 23-1 Components of the Respiratory System • The Respiratory Defense System • Consists of a series of filtration mechanisms • Removes particles and pathogens
  21. 21. © 2012 Pearson Education, Inc. 23-1 Components of the Respiratory System • Components of the Respiratory Defense System • Mucous cells and mucous glands • Produce mucus that bathes exposed surfaces • Cilia • Sweep debris trapped in mucus toward the pharynx (mucus escalator) • Filtration in nasal cavity removes large particles • Alveolar macrophages engulf small particles that reach lungs
  22. 22. © 2012 Pearson Education, Inc. 23-2 Upper Respiratory Tract • The Nose • Air enters the respiratory system • Through nostrils or external nares • Into nasal vestibule • Nasal hairs • Are in nasal vestibule • Are the first particle filtration system
  23. 23. © 2012 Pearson Education, Inc. 23-2 Upper Respiratory Tract • The Nasal Cavity • The nasal septum • Divides nasal cavity into left and right • Superior portion of nasal cavity is the olfactory region • Provides sense of smell • Mucous secretions from paranasal sinus and tears • Clean and moisten the nasal cavity
  24. 24. © 2012 Pearson Education, Inc. 23-2 Upper Respiratory Tract • Air Flow • From vestibule to internal nares • Through superior, middle, and inferior meatuses • Meatuses are constricted passageways that produce air turbulence • Warm and humidify incoming air • Trap particles
  25. 25. © 2012 Pearson Education, Inc. 23-2 Upper Respiratory Tract • The Palates • Hard palate • Forms floor of nasal cavity • Separates nasal and oral cavities • Soft palate • Extends posterior to hard palate • Divides superior nasopharynx from lower pharynx
  26. 26. © 2012 Pearson Education, Inc. 23-2 Upper Respiratory Tract • Air Flow • Nasal cavity opens into nasopharynx through internal nares • The Nasal Mucosa • Warms and humidifies inhaled air for arrival at lower respiratory organs • Breathing through mouth bypasses this important step
  27. 27. © 2012 Pearson Education, Inc. Figure 23-3a Structures of the Upper Respiratory System Dorsum nasi Apex Nasal cartilages External nares The nasal cartilages and external landmarks on the nose
  28. 28. © 2012 Pearson Education, Inc. Figure 23-3b Structures of the Upper Respiratory System A frontal section through the head, showing the meatuses and the maxillary sinuses and air cells of the ethmoidal labyrinth Tongue Inferior meatus Inferior nasal concha Maxillary sinus Middle meatus Middle nasal concha Superior meatus Superior nasal concha Lens Right eye Frontal sinus Cranial cavityEthmoidal air cell Medial rectus muscle Lateral rectus muscle Nasal septum Hard palate Vomer Perpendicular plate of ethmoid Mandible
  29. 29. © 2012 Pearson Education, Inc. Figure 23-3c Structures of the Upper Respiratory System Nasal cavity Internal nares Nasopharynx Pharyngeal tonsil Pharynx Oropharynx Laryngopharynx Epiglottis Entrance to auditory tube Glottis Vocal fold Esophagus The nasal cavity and pharynx, as seen in sagittal section with the nasal septum removed Thyroid gland Trachea Cricoid cartilage Thyroid cartilage Hyoid bone Lingual tonsil Mandible Palatine tonsil Soft palate Oral cavity Tongue Hard palate External nares Nasal vestibule Inferior Middle Superior Nasal conchae Frontal sinus
  30. 30. © 2012 Pearson Education, Inc. 23-2 Upper Respiratory Tract • The Pharynx • A chamber shared by digestive and respiratory systems • Extends from internal nares to entrances to larynx and esophagus • Divided into three parts 1. The nasopharynx 2. The oropharynx 3. The laryngopharynx
  31. 31. © 2012 Pearson Education, Inc. 23-2 Upper Respiratory Tract • The Nasopharynx • Superior portion of pharynx • Contains pharyngeal tonsils and openings to left and right auditory tubes • The Oropharynx • Middle portion of pharynx • Communicates with oral cavity • The Laryngopharynx • Inferior portion of pharynx • Extends from hyoid bone to entrance of larynx and esophagus
  32. 32. © 2012 Pearson Education, Inc. 23-3 The Larynx • Air Flow • From the pharynx enters the larynx • A cartilaginous structure that surrounds the glottis, which is a narrow opening
  33. 33. © 2012 Pearson Education, Inc. 23-3 The Larynx • Cartilages of the Larynx • Three large, unpaired cartilages form the larynx 1. Thyroid cartilage 2. Cricoid cartilage 3. Epiglottis
  34. 34. © 2012 Pearson Education, Inc. 23-3 The Larynx • The Thyroid Cartilage • Is hyaline cartilage • Forms anterior and lateral walls of larynx • Anterior surface called laryngeal prominence, or Adam’s apple • Ligaments attach to hyoid bone, epiglottis, and laryngeal cartilages
  35. 35. © 2012 Pearson Education, Inc. 23-3 The Larynx • The Cricoid Cartilage • Is hyaline cartilage • Forms posterior portion of larynx • Ligaments attach to first tracheal cartilage • Articulates with arytenoid cartilages
  36. 36. © 2012 Pearson Education, Inc. 23-3 The Larynx • The Epiglottis • Composed of elastic cartilage • Ligaments attach to thyroid cartilage and hyoid bone
  37. 37. © 2012 Pearson Education, Inc. 23-3 The Larynx • Cartilage Functions • Thyroid and cricoid cartilages support and protect: • The glottis • The entrance to trachea • During swallowing: • The larynx is elevated • The epiglottis folds back over glottis • Prevents entry of food and liquids into respiratory tract
  38. 38. © 2012 Pearson Education, Inc. 23-3 The Larynx • The Larynx Contains Three Pairs of Smaller Hyaline Cartilages 1. Arytenoid cartilages 2. Corniculate cartilages 3. Cuneiform cartilages
  39. 39. © 2012 Pearson Education, Inc. Figure 23-4a The Anatomy of the Larynx Epiglottis Lesser cornu Hyoid bone Thyrohyoid ligament Laryngeal prominence Thyroid cartilage Cricothyroid ligament Cricoid cartilage Cricotracheal ligament Tracheal cartilages Anterior view Trachea Larynx
  40. 40. © 2012 Pearson Education, Inc. Figure 23-4b The Anatomy of the Larynx Epiglottis Thyroid cartilage Tracheal cartilages Posterior view Vestibular ligament Vocal ligament Arytenoid cartilage
  41. 41. © 2012 Pearson Education, Inc. Figure 23-4c The Anatomy of the Larynx Vestibular ligament Vocal ligament Arytenoid cartilage Cricothyroid ligament Cricotracheal ligament Sagittal section ANTERIOR POSTERIOR Epiglottis Hyoid bone Thyroid cartilage Corniculate cartilage Cricoid cartilage Tracheal cartilages
  42. 42. © 2012 Pearson Education, Inc. 23-3 The Larynx • Cartilage Functions • Corniculate and arytenoid cartilages function in: • Opening and closing of glottis • Production of sound
  43. 43. © 2012 Pearson Education, Inc. 23-3 The Larynx • Ligaments of the Larynx • Vestibular ligaments and vocal ligaments • Extend between thyroid cartilage and arytenoid cartilages • Are covered by folds of laryngeal epithelium that project into glottis
  44. 44. © 2012 Pearson Education, Inc. 23-3 The Larynx • The Vestibular Ligaments • Lie within vestibular folds • Which protect delicate vocal folds • Sound Production • Air passing through glottis • Vibrates vocal folds • Produces sound waves
  45. 45. © 2012 Pearson Education, Inc. 23-3 The Larynx • Sound Production • Sound is varied by: • Tension on vocal folds • Vocal folds involved with sound are known as vocal cords • Voluntary muscles (position arytenoid cartilage relative to thyroid cartilage) • Speech is produced by: • Phonation • Sound production at the larynx • Articulation • Modification of sound by other structures
  46. 46. © 2012 Pearson Education, Inc. Figure 23-5a The Glottis and Surrounding Structures Corniculate cartilage Glottis in the open position. Glottis (open) POSTERIOR ANTERIOR Aryepiglottic fold Cuneiform cartilage Vestibular fold Vocal fold Epiglottis Root of tongue
  47. 47. © 2012 Pearson Education, Inc. Figure 23-5b The Glottis and Surrounding Structures Glottis in the closed position. Root of tongue Epiglottis Vocal fold Vestibular fold Glottis (closed) Corniculate cartilage POSTERIOR ANTERIOR
  48. 48. © 2012 Pearson Education, Inc. Figure 23-5c The Glottis and Surrounding Structures This photograph is a representative laryngoscopic view. For this view the camera is positioned within the oro- pharynx, just superior to the larynx. Root of tongue Epiglottis Vocal fold Vestibular fold Cuneiform cartilage in aryepiglottic fold Glottis (open) Corniculate cartilage
  49. 49. © 2012 Pearson Education, Inc. 23-3 The Larynx • The Laryngeal Musculature • The larynx is associated with: 1. Muscles of neck and pharynx 2. Intrinsic muscles • Control vocal folds • Open and close glottis
  50. 50. © 2012 Pearson Education, Inc. 23-4 The Trachea • The Trachea • Also called the windpipe • Extends from the cricoid cartilage into mediastinum • Where it branches into right and left pulmonary bronchi • The submucosa • Beneath mucosa of trachea • Contains mucous glands
  51. 51. © 2012 Pearson Education, Inc. Figure 23-6b The Anatomy of the Trachea A cross-sectional view The trachea Lumen of trachea Tracheal cartilage Respiratory epithelium Thyroid gland Trachealis muscle Esophagus LM × 3
  52. 52. © 2012 Pearson Education, Inc. 23-4 The Trachea • The Tracheal Cartilages • 15–20 tracheal cartilages • Strengthen and protect airway • Discontinuous where trachea contacts esophagus • Ends of each tracheal cartilage are connected by: • An elastic ligament and trachealis muscle
  53. 53. © 2012 Pearson Education, Inc. 23-4 The Trachea • The Primary Bronchi • Right and Left Primary Bronchi • Separated by an internal ridge (the carina) • The Right Primary Bronchus • Is larger in diameter than the left • Descends at a steeper angle
  54. 54. © 2012 Pearson Education, Inc. Figure 23-6a The Anatomy of the Trachea Hyoid bone Larynx Trachea Root of right lung Tracheal cartilages Location of carina (internal ridge) Lung tissue Root of left lung Primary bronchi Secondary bronchi RIGHT LUNG LEFT LUNG A diagrammatic anterior view showing the plane of section for part (b)
  55. 55. © 2012 Pearson Education, Inc. 23-4 The Trachea • The Primary Bronchi • Hilum • Where pulmonary nerves, blood vessels, lymphatics enter lung • Anchored in meshwork of connective tissue • The root of the lung • Complex of connective tissues, nerves, and vessels in hilum • Anchored to the mediastinum ANIMATION Respiration: Respiratory Tract
  56. 56. © 2012 Pearson Education, Inc. 23-5 The Lungs • The Lungs • Left and right lungs • Are in left and right pleural cavities • The base • Inferior portion of each lung rests on superior surface of diaphragm • Lobes of the lungs • Lungs have lobes separated by deep fissures
  57. 57. © 2012 Pearson Education, Inc. 23-5 The Lungs • Lobes and Surfaces of the Lungs • The right lung has three lobes • Superior, middle, and inferior • Separated by horizontal and oblique fissures • The left lung has two lobes • Superior and inferior • Separated by an oblique fissure
  58. 58. © 2012 Pearson Education, Inc. 23-5 The Lungs • Lung Shape • Right lung • Is wider • Is displaced upward by liver • Left lung • Is longer • Is displaced leftward by the heart forming the cardiac notch
  59. 59. © 2012 Pearson Education, Inc. Figure 23-7a The Gross Anatomy of the Lungs Superior lobe RIGHT LUNG Horizontal fissure Middle lobe Inferior lobe Oblique fissure Thoracic cavity, anterior view Liver, right lobe Liver, left lobe Boundary between right and left pleural cavities Superior lobe LEFT LUNG Oblique fissure Fibrous layer of pericardium Inferior lobe Falciform ligament Cut edge of diaphragm
  60. 60. © 2012 Pearson Education, Inc. Figure 23-7b The Gross Anatomy of the Lungs ApexApex Superior lobe Oblique fissure Inferior lobe Base Left lung The cardiac notch accommodates the pericardial cavity, which sits to the left of the midline. Right lung Superior lobe Middle lobe Inferior lobe Horizontal fissure Oblique fissure Base The curving anterior and lateral surfaces of each lung follow the inner contours of the rib cage. Lateral Surfaces
  61. 61. © 2012 Pearson Education, Inc. Figure 23-7c The Gross Anatomy of the Lungs Medial Surfaces The medial surfaces, which contain the hilium, have more irregular shapes. The medial surfaces of both lungs bear grooves that mark the positions of the great vessels and the heart. Apex Superior lobe Pulmonary artery Pulmonary veins Horizontal fissure Oblique fissure Inferior lobe Middle lobe Right lung Left lung Base Base Inferior lobe Apex Superior lobe Groove for aorta Pulmonary artery Pulmonary veins Oblique fissure The hilium of the lung is a groove that allows passage of the primary bronchi, pulmonary vessels, nerves, and lymphatics. Diaphragmatic surface
  62. 62. © 2012 Pearson Education, Inc. Figure 23-8 The Relationship between the Lungs and Heart Pericardial cavity Right lung, middle lobe Oblique fissure Right pleural cavity Atria Esophagus Aorta Right lung, inferior lobe Spinal cord Left lung, inferior lobe Mediastinum Bronchi Parietal pleura Left pleural cavity Visceral pleural Left lung, superior lobe Ventricles Body of sternum Rib
  63. 63. © 2012 Pearson Education, Inc. 23-5 The Lungs • The Bronchi • The Bronchial Tree • Is formed by the primary bronchi and their branches • Extrapulmonary Bronchi • The left and right bronchi branches outside the lungs • Intrapulmonary Bronchi • Branches within the lungs
  64. 64. © 2012 Pearson Education, Inc. 23-5 The Lungs • A Primary Bronchus • Branches to form secondary bronchi (lobar bronchi) • One secondary bronchus goes to each lobe • Secondary Bronchi • Branch to form tertiary bronchi (segmental bronchi) • Each segmental bronchus • Supplies air to a single bronchopulmonary segment
  65. 65. © 2012 Pearson Education, Inc. 23-5 The Lungs • Bronchopulmonary Segments • The right lung has 10 • The left lung has 8 or 9 • Bronchial Structure • The walls of primary, secondary, and tertiary bronchi • Contain progressively less cartilage and more smooth muscle • Increased smooth muscle tension affects airway constriction and resistance
  66. 66. © 2012 Pearson Education, Inc. 23-5 The Lungs • Bronchitis • Inflammation of bronchial walls • Causes constriction and breathing difficulty
  67. 67. © 2012 Pearson Education, Inc. 23-5 The Lungs • The Bronchioles • Each tertiary bronchus branches into multiple bronchioles • Bronchioles branch into terminal bronchioles • One tertiary bronchus forms about 6500 terminal bronchioles • Bronchiole Structure • Bronchioles • Have no cartilage • Are dominated by smooth muscle
  68. 68. © 2012 Pearson Education, Inc. 23-5 The Lungs • Autonomic Control • Regulates smooth muscle • Controls diameter of bronchioles • Controls airflow and resistance in lungs
  69. 69. © 2012 Pearson Education, Inc. 23-5 The Lungs • Bronchodilation • Dilation of bronchial airways • Caused by sympathetic ANS activation • Reduces resistance • Bronchoconstriction • Constricts bronchi • Caused by: • Parasympathetic ANS activation • Histamine release (allergic reactions)
  70. 70. © 2012 Pearson Education, Inc. 23-5 The Lungs • Asthma • Excessive stimulation and bronchoconstriction • Stimulation severely restricts airflow
  71. 71. © 2012 Pearson Education, Inc. 23-5 The Lungs • Pulmonary Lobules • Trabeculae • Fibrous connective tissue partitions from root of lung • Contain supportive tissues and lymphatic vessels • Branch repeatedly • Divide lobes into increasingly smaller compartments • Pulmonary lobules are divided by the smallest trabecular partitions (interlobular septa)
  72. 72. © 2012 Pearson Education, Inc. Figure 23-9a The Bronchi and Lobules of the Lung Bronchopulmonary segment Respiratory bronchiole Terminal bronchiole Bronchioles Smaller bronchi Alveoli in a pulmonary lobule Tertiary bronchi Secondary bronchus Visceral pleura Left primary bronchus Trachea Cartilage plates The branching pattern of bronchi in the left lung, simplified
  73. 73. © 2012 Pearson Education, Inc. Figure 23-9b The Bronchi and Lobules of the Lung Respiratory epithelium Bronchiole Bronchial artery (red), vein (blue), and nerve (yellow) Terminal bronchiole Respiratory bronchiole Elastic fibers Capillary bedsBranch of pulmonary vein Alveolar duct Arteriole Lymphatic vessel Alveoli Alveolar sac Interlobular septum Visceral pleura Pleural cavity Parietal pleura The structure of a single pulmonary lobule, part of a bronchopulmonary segment Branch of pulmonary artery Smooth muscle around terminal bronchiole
  74. 74. © 2012 Pearson Education, Inc. 23-5 The Lungs • Pulmonary Lobules • Each terminal bronchiole delivers air to a single pulmonary lobule • Each pulmonary lobule is supplied by pulmonary arteries and veins • Each terminal bronchiole branches to form several respiratory bronchioles, where gas exchange takes place
  75. 75. © 2012 Pearson Education, Inc. 23-5 The Lungs • Alveolar Ducts and Alveoli • Respiratory bronchioles are connected to alveoli along alveolar ducts • Alveolar ducts end at alveolar sacs • Common chambers connected to many individual alveoli • Each alveolus has an extensive network of capillaries • Surrounded by elastic fibers
  76. 76. © 2012 Pearson Education, Inc. Figure 23-10a Respiratory Tissue Respiratory bronchiole Alveoli Alveolar sac Arteriole Alveolarduct Histology of the lung LM × 14 Low power micrograph of lung tissue
  77. 77. © 2012 Pearson Education, Inc. Figure 23-10b Respiratory Tissue SEM of lung tissue showing the appearance and organization of the alveoli Alveolar sac Alveoli Alveolar duct SEM × 125Lung tissue
  78. 78. © 2012 Pearson Education, Inc. 23-5 The Lungs • Alveolar Epithelium • Consists of simple squamous epithelium • Consists of thin, delicate pneumocytes type I • Patrolled by alveolar macrophages (dust cells) • Contains pneumocytes type II (septal cells) that produce surfactant
  79. 79. © 2012 Pearson Education, Inc. 23-5 The Lungs • Surfactant • Is an oily secretion • Contains phospholipids and proteins • Coats alveolar surfaces and reduces surface tension
  80. 80. © 2012 Pearson Education, Inc. Figure 23-11a Alveolar Organization Smooth muscle Elastic fibers Capillaries Respiratory bronchiole Alveolar duct Alveolus Alveolar sac The basic structure of a portion of a single lobule.
  81. 81. © 2012 Pearson Education, Inc. Figure 23-11b Alveolar Organization Pneumocyte type I Alveolar macrophage Pneumocyte type II Elastic fibers Capillary Alveolar macrophage A diagrammatic view of alveolar structure. A single capillary may be involved in gas exchange with several alveoli simultaneously. Endothelial cell of capillary
  82. 82. © 2012 Pearson Education, Inc. 23-5 The Lungs • Respiratory Distress Syndrome • Difficult respiration • Due to alveolar collapse • Caused when pneumocytes type II do not produce enough surfactant • Respiratory Membrane • The thin membrane of alveoli where gas exchange takes place
  83. 83. © 2012 Pearson Education, Inc. 23-5 The Lungs • Three Layers of the Respiratory Membrane 1. Squamous epithelial cells lining the alveolus 2. Endothelial cells lining an adjacent capillary 3. Fused basement membranes between the alveolar and endothelial cells
  84. 84. © 2012 Pearson Education, Inc. Figure 23-11c Alveolar Organization 0.5 µm Fused basement membrane Alveolar epithelium Surfactant Nucleus of endothelial cell Capillary endothelium Red blood cell Capillary lumen Alveolar air space The respiratory membrane, which consists of an alveolar epithelial cell, a capillary endothelial cell, and their fused basement membranes.
  85. 85. © 2012 Pearson Education, Inc. 23-5 The Lungs • Diffusion • Across respiratory membrane is very rapid • Because distance is short • Gases (O2 and CO2) are lipid soluble • Inflammation of Lobules • Also called pneumonia • Causes fluid to leak into alveoli • Compromises function of respiratory membrane
  86. 86. © 2012 Pearson Education, Inc. 23-5 The Lungs • Blood Supply to the Lungs • Respiratory exchange surfaces receive blood • From arteries of pulmonary circuit • A capillary network surrounds each alveolus • As part of the respiratory membrane • Blood from alveolar capillaries • Passes through pulmonary venules and veins • Returns to left atrium • Also site of angiotensin-converting enzyme (ACE)
  87. 87. © 2012 Pearson Education, Inc. 23-5 The Lungs • Blood Supply to the Lungs • Capillaries supplied by bronchial arteries • Provide oxygen and nutrients to tissues of conducting passageways of lung • Venous blood bypasses the systemic circuit and flows into pulmonary veins
  88. 88. © 2012 Pearson Education, Inc. 23-5 The Lungs • Blood Pressure • In pulmonary circuit is low (30 mm Hg) • Pulmonary vessels are easily blocked by blood clots, fat, or air bubbles • Causing pulmonary embolism
  89. 89. © 2012 Pearson Education, Inc. 23-5 The Lungs • The Pleural Cavities and Pleural Membranes • Two pleural cavities • Are separated by the mediastinum • Each pleural cavity: • Holds a lung • Is lined with a serous membrane (the pleura)
  90. 90. © 2012 Pearson Education, Inc. 23-5 The Lungs • The Pleura • Consists of two layers 1. Parietal pleura 2. Visceral pleura • Pleural fluid • Lubricates space between two layers
  91. 91. © 2012 Pearson Education, Inc. 23-6 Introduction to Gas Exchange • Respiration • Refers to two integrated processes 1. External respiration • Includes all processes involved in exchanging O2 and CO2 with the environment 2. Internal respiration • Result of cellular respiration • Involves the uptake of O2 and production of CO2 within individual cells
  92. 92. © 2012 Pearson Education, Inc. 23-6 Introduction to Gas Exchange • Three Processes of External Respiration 1. Pulmonary ventilation (breathing) 2. Gas diffusion • Across membranes and capillaries 3. Transport of O2 and CO2 • Between alveolar capillaries • Between capillary beds in other tissues
  93. 93. © 2012 Pearson Education, Inc. Figure 23-12 An Overview of the Key Steps in Respiration Respiration External Respiration Pulmonary ventilation Gas diffusion O2 transport Gas diffusion Tissues Gas diffusion Gas diffusion CO2 transport Lungs Internal Respiration
  94. 94. © 2012 Pearson Education, Inc. 23-6 Introduction to Gas Exchange • Abnormal External Respiration Is Dangerous • Hypoxia • Low tissue oxygen levels • Anoxia • Complete lack of oxygen
  95. 95. © 2012 Pearson Education, Inc. 23-7 Pulmonary Ventilation • Pulmonary Ventilation • Is the physical movement of air in and out of respiratory tract • Provides alveolar ventilation • The Movement of Air • Atmospheric pressure • The weight of air • Has several important physiological effects
  96. 96. © 2012 Pearson Education, Inc. 23-7 Pulmonary Ventilation • Gas Pressure and Volume • Boyle’s Law • Defines the relationship between gas pressure and volume P = 1/V • In a contained gas: • External pressure forces molecules closer together • Movement of gas molecules exerts pressure on container
  97. 97. © 2012 Pearson Education, Inc. Figure 23-13 Gas Pressure and Volume Relationships
  98. 98. © 2012 Pearson Education, Inc. Figure 23-13a Gas Pressure and Volume Relationships If you decrease the volume of the container, collisions occur more frequently per unit time, elevating the pressure of the gas.
  99. 99. © 2012 Pearson Education, Inc. Figure 23-13b Gas Pressure and Volume Relationships If you increase the volume, fewer collisions occur per unit time, because it takes longer for a gas molecule to travel from one wall to another. As a result, the gas pressure inside the container declines.
  100. 100. © 2012 Pearson Education, Inc. 23-7 Pulmonary Ventilation • Pressure and Airflow to the Lungs • Air flows from area of higher pressure to area of lower pressure • A Respiratory Cycle • Consists of: • An inspiration (inhalation) • An expiration (exhalation)
  101. 101. © 2012 Pearson Education, Inc. 23-7 Pulmonary Ventilation • Pulmonary Ventilation • Causes volume changes that create changes in pressure • Volume of thoracic cavity changes • With expansion or contraction of diaphragm or rib cage
  102. 102. © 2012 Pearson Education, Inc. Figure 23-14a Mechanisms of Pulmonary Ventilation Ribs and sternum elevate Diaphragm contracts As the rib cage is elevated or the diaphragm is depressed, the volume of the thoracic cavity increases.
  103. 103. © 2012 Pearson Education, Inc. Figure 23-14b Mechanisms of Pulmonary Ventilation Diaphragm Pleural cavity Cardiac notch At rest. Pressure outside and inside are equal, so no air movement occurs Poutside = Pinside
  104. 104. © 2012 Pearson Education, Inc. Figure 23-14c Mechanisms of Pulmonary Ventilation Poutside > Pinside Volume increases Inhalation. Elevation of the rib cage and contraction of the diaphragm increase the size of the thoracic cavity. Pressure within the thoracic cavity decreases, and air flows into the lungs. Pressure inside falls, so air flows in
  105. 105. © 2012 Pearson Education, Inc. Figure 23-14d Mechanisms of Pulmonary Ventilation Poutside < Pinside Volume decreases Pressure inside rises, so air flows out Exhalation. When the rib cage returns to its original position and the diaphragm relaxes, the volume of the thoracic cavity decreases. Pressure rises, and air moves out of the lungs.
  106. 106. © 2012 Pearson Education, Inc. 23-7 Pulmonary Ventilation • Compliance • An indicator of expandability • Low compliance requires greater force • High compliance requires less force • Factors That Affect Compliance • Connective tissue structure of the lungs • Level of surfactant production • Mobility of the thoracic cage
  107. 107. © 2012 Pearson Education, Inc. 23-7 Pulmonary Ventilation • Pressure Changes during Inhalation and Exhalation • Can be measured inside or outside the lungs • Normal atmospheric pressure • 1 atm = 760 mm Hg ANIMATION Respiration: Pressure Gradients
  108. 108. © 2012 Pearson Education, Inc. 23-7 Pulmonary Ventilation • The Intrapulmonary Pressure • Also called intra-alveolar pressure • Is relative to atmospheric pressure • In relaxed breathing, the difference between atmospheric pressure and intrapulmonary pressure is small • About −1 mm Hg on inhalation or +1 mm Hg on exhalation
  109. 109. © 2012 Pearson Education, Inc. 23-7 Pulmonary Ventilation • Maximum Intrapulmonary Pressure • Maximum straining, a dangerous activity, can increase range • From −30 mm Hg to +100 mm Hg
  110. 110. © 2012 Pearson Education, Inc. 23-7 Pulmonary Ventilation • The Intrapleural Pressure • Pressure in space between parietal and visceral pleura • Averages −4 mm Hg • Maximum of −18 mm Hg • Remains below atmospheric pressure throughout respiratory cycle
  111. 111. © 2012 Pearson Education, Inc. Table 23-1 The Four Most Common Methods of Reporting Gas Pressures
  112. 112. © 2012 Pearson Education, Inc. 23-7 Pulmonary Ventilation • The Respiratory Cycle • Cyclical changes in intrapleural pressure operate the respiratory pump • Which aids in venous return to heart • Tidal Volume (VT) • Amount of air moved in and out of lungs in a single respiratory cycle
  113. 113. © 2012 Pearson Education, Inc. 23-7 Pulmonary Ventilation • Injury to the Chest Wall • Pneumothorax allows air into pleural cavity • Atelectasis (also called a collapsed lung) is a result of pneumothorax
  114. 114. © 2012 Pearson Education, Inc. Figure 23-15 Pressure and Volume Changes during Inhalation and Exhalation Trachea Bronchi Lung Diaphragm Right pleural cavity Left pleural cavity Intrapulmonary pressure (mm Hg) Intrapleural pressure (mm Hg) Tidal volume (mL) Changes in intrapulmonary pressure during a single respiratory cycle Changes in intrapleural pressure during a single respiratory cycle A plot of tidal volume, the amount of air moving into and out of the lungs during a single respiratory cycle Time (sec) INHALATION EXHALATION
  115. 115. © 2012 Pearson Education, Inc. 23-7 Pulmonary Ventilation • The Respiratory Muscles • Most important are: • The diaphragm • External intercostal muscles of the ribs • Accessory respiratory muscles • Activated when respiration increases significantly
  116. 116. © 2012 Pearson Education, Inc. 23-7 Pulmonary Ventilation • The Mechanics of Breathing • Inhalation • Always active • Exhalation • Active or passive
  117. 117. © 2012 Pearson Education, Inc. 23-7 Pulmonary Ventilation • Muscles Used in Inhalation • Diaphragm • Contraction draws air into lungs • 75% of normal air movement • External intercostal muscles • Assist inhalation • 25% of normal air movement • Accessory muscles assist in elevating ribs • Sternocleidomastoid • Serratus anterior • Pectoralis minor • Scalene muscles
  118. 118. © 2012 Pearson Education, Inc. Figure 23-16a The Respiratory Muscles Diaphragm contracts Ribs and sternum elevate Movements of the ribs and diaphragm that increase the volume of the thoracic cavity. Diaphragmatic movements were also illustrated in Figure 23–14.
  119. 119. © 2012 Pearson Education, Inc. Figure 23-16b The Respiratory Muscles Accessory Muscles of Inhalation Sternocleidomastoid muscle Scalene muscles Pectoralis minor muscle Serratus anterior muscle Primary Muscle of Inhalation Diaphragm Internal oblique muscle Rectus abdominus External oblique muscle Transversus thoracis muscle Internal intercostal muscles Accessory Muscles of Exhalation Primary Muscle of Inhalation External intercostal muscles An anterior view at rest (with no air movement), showing the primary and accessory respiratory muscles.
  120. 120. © 2012 Pearson Education, Inc. Figure 23-16c The Respiratory Muscles Primary Muscle of Inhalation Inhalation. A lateral view during inhalation, showing the muscles that elevate the ribs. Sternocleidomastoid muscle Accessory Muscle of Inhalation (active when needed) Scalene muscles Pectoralis minor muscle Serratus anterior muscle External intercostal muscles Diaphragm
  121. 121. © 2012 Pearson Education, Inc. 23-7 Pulmonary Ventilation • Muscles Used in Exhalation • Internal intercostal and transversus thoracis muscles • Depress the ribs • Abdominal muscles • Compress the abdomen • Force diaphragm upward
  122. 122. © 2012 Pearson Education, Inc. Figure 23-16d The Respiratory Muscles Exhalation. A lateral view during exhalation, showing the muscles that depress the ribs. The abdominal muscles that assist in exhalation are represented by a single muscle (the rectus abdominis). Rectus abdominis and other abdominal muscles (not shown) Internal intercostal muscles Transversus thoracis muscle Accessory Muscles of Exhalation (active when needed)
  123. 123. © 2012 Pearson Education, Inc. 23-7 Pulmonary Ventilation • Modes of Breathing • Respiratory movements are classified • By pattern of muscle activity • Quiet breathing • Forced breathing
  124. 124. © 2012 Pearson Education, Inc. 23-7 Pulmonary Ventilation • Quiet Breathing (Eupnea) • Involves active inhalation and passive exhalation • Diaphragmatic breathing or deep breathing • Is dominated by diaphragm • Costal breathing or shallow breathing • Is dominated by rib cage movements
  125. 125. © 2012 Pearson Education, Inc. 23-7 Pulmonary Ventilation • Elastic Rebound • When inhalation muscles relax • Elastic components of muscles and lungs recoil • Returning lungs and alveoli to original position
  126. 126. © 2012 Pearson Education, Inc. 23-7 Pulmonary Ventilation • Forced Breathing (Hyperpnea) • Involves active inhalation and exhalation • Assisted by accessory muscles • Maximum levels occur in exhaustion
  127. 127. © 2012 Pearson Education, Inc. 23-7 Pulmonary Ventilation • Respiratory Rates and Volumes • Respiratory system adapts to changing oxygen demands by varying: • The number of breaths per minute (respiratory rate) • The volume of air moved per breath (tidal volume)
  128. 128. © 2012 Pearson Education, Inc. 23-7 Pulmonary Ventilation • The Respiratory Minute Volume (VE) • Amount of air moved per minute • Is calculated by: respiratory rate × tidal volume • Measures pulmonary ventilation
  129. 129. © 2012 Pearson Education, Inc. 23-7 Pulmonary Ventilation • Alveolar Ventilation (VA) • Only a part of respiratory minute volume reaches alveolar exchange surfaces • Volume of air remaining in conducting passages is anatomic dead space • Alveolar ventilation is the amount of air reaching alveoli each minute • Calculated as: (tidal volume − anatomic dead space) × respiratory rate
  130. 130. © 2012 Pearson Education, Inc. 23-7 Pulmonary Ventilation • Alveolar Gas Content • Alveoli contain less O2, more CO2 than atmospheric air • Because air mixes with exhaled air
  131. 131. © 2012 Pearson Education, Inc. 23-7 Pulmonary Ventilation • Relationships among VT, VE, and VA • Determined by respiratory rate and tidal volume • For a given respiratory rate: • Increasing tidal volume increases alveolar ventilation rate • For a given tidal volume: • Increasing respiratory rate increases alveolar ventilation
  132. 132. © 2012 Pearson Education, Inc. 23-7 Pulmonary Ventilation • Respiratory Performance and Volume Relationships • Total lung volume is divided into a series of volumes and capacities useful in diagnosing problems • Four Pulmonary Volumes 1. Resting tidal volume (Vt) 2. Expiratory reserve volume (ERV) 3. Residual volume 4. Inspiratory reserve volume (IRV)
  133. 133. © 2012 Pearson Education, Inc. 23-7 Pulmonary Ventilation • Resting Tidal Volume (Vt) • In a normal respiratory cycle • Expiratory Reserve Volume (ERV) • After a normal exhalation • Residual Volume • After maximal exhalation • Minimal volume (in a collapsed lung) • Inspiratory Reserve Volume (IRV) • After a normal inspiration
  134. 134. © 2012 Pearson Education, Inc. 23-7 Pulmonary Ventilation • Four Calculated Respiratory Capacities 1. Inspiratory capacity • Tidal volume + inspiratory reserve volume 2. Functional residual capacity (FRC) • Expiratory reserve volume + residual volume 3. Vital capacity • Expiratory reserve volume + tidal volume + inspiratory reserve volume
  135. 135. © 2012 Pearson Education, Inc. 23-7 Pulmonary Ventilation • Four Calculated Respiratory Capacities 4. Total lung capacity • Vital capacity + residual volume • Pulmonary Function Tests • Measure rates and volumes of air movements
  136. 136. © 2012 Pearson Education, Inc. Figure 23-17 Pulmonary Volumes and Capacities Pulmonary Volumes and Capacities (adult male) Resting tidal volume (VT = 500 mL) Inspiratory reserve volume (IRV) Inspiratory capacity Vital capacity Total lung capacity Expiratory reserve volume (ERV) Residual volume Functional residual capacity (FRC) Minimal volume (30–120 mL) Time 0 1200 2200 2700 Volume(mL) 6000
  137. 137. © 2012 Pearson Education, Inc. Figure 23-17 Pulmonary Volumes and Capacities Gender Differences Vital capacity Males Females Total lung capacity 6000 mL 4200 mL Residual volume 1200Residual volume 1200 Inspiratory capacity Functional residual capacity IRV 3300 1900 500500VT ERV 1000 700 1100
  138. 138. © 2012 Pearson Education, Inc. 23-8 Gas Exchange • Gas Exchange • Occurs between blood and alveolar air • Across the respiratory membrane • Depends on: 1. Partial pressures of the gases 2. Diffusion of molecules between gas and liquid
  139. 139. © 2012 Pearson Education, Inc. 23-8 Gas Exchange • The Gas Laws • Diffusion occurs in response to concentration gradients • Rate of diffusion depends on physical principles, or gas laws • For example, Boyle’s law
  140. 140. © 2012 Pearson Education, Inc. 23-8 Gas Exchange • Dalton’s Law and Partial Pressures • Composition of Air • Nitrogen (N2) is about 78.6% • Oxygen (O2) is about 20.9% • Water vapor (H2O) is about 0.5% • Carbon dioxide (CO2) is about 0.04%
  141. 141. © 2012 Pearson Education, Inc. 23-8 Gas Exchange • Dalton’s Law and Partial Pressures • Atmospheric pressure (760 mm Hg) • Produced by air molecules bumping into each other • Each gas contributes to the total pressure • In proportion to its number of molecules (Dalton’s law)
  142. 142. © 2012 Pearson Education, Inc. 23-8 Gas Exchange • Partial Pressure • The pressure contributed by each gas in the atmosphere • All partial pressures together add up to 760 mm Hg
  143. 143. © 2012 Pearson Education, Inc. 23-8 Gas Exchange • Diffusion between Liquids and Gases • Henry’s Law • When gas under pressure comes in contact with liquid • Gas dissolves in liquid until equilibrium is reached • At a given temperature • Amount of a gas in solution is proportional to partial pressure of that gas • The actual amount of a gas in solution (at given partial pressure and temperature) • Depends on the solubility of that gas in that particular liquid
  144. 144. © 2012 Pearson Education, Inc. Figure 23-18 Henry’s Law and the Relationship between Solubility and Pressure
  145. 145. © 2012 Pearson Education, Inc. Figure 23-18a Henry’s Law and the Relationship between Solubility and Pressure Increasing the pressure drives gas molecules into solution until an equilibrium is established. Example Soda is put into the can under pressure, and the gas (carbon dioxide) is in solution at equilibrium.
  146. 146. © 2012 Pearson Education, Inc. Figure 23-18b Henry’s Law and the Relationship between Solubility and Pressure When the gas pressure decreases, dissolved gas molecules leave the solution until a new equilibrium is reached. Example Opening the can of soda relieves the pressure, and bubbles form as the dissolved gas leaves the solution.
  147. 147. © 2012 Pearson Education, Inc. 23-8 Gas Exchange • Solubility in Body Fluids • CO2 is very soluble • O2 is less soluble • N2 has very low solubility
  148. 148. © 2012 Pearson Education, Inc. 23-8 Gas Exchange • Normal Partial Pressures • In pulmonary vein plasma • PCO 2 = 40 mm Hg • PO 2 = 100 mm Hg • PN 2 = 573 mm Hg
  149. 149. © 2012 Pearson Education, Inc. Table 23-1 The Four Most Common Methods of Reporting Gas Pressures
  150. 150. © 2012 Pearson Education, Inc. 23-8 Gas Exchange • Diffusion and Respiratory Function • Direction and rate of diffusion of gases across the respiratory membrane • Determine different partial pressures and solubilities
  151. 151. © 2012 Pearson Education, Inc. 23-8 Gas Exchange • Five Reasons for Efficiency of Gas Exchange 1. Substantial differences in partial pressure across the respiratory membrane 2. Distances involved in gas exchange are short 3. O2 and CO2 are lipid soluble 4. Total surface area is large 5. Blood flow and airflow are coordinated
  152. 152. © 2012 Pearson Education, Inc. 23-8 Gas Exchange • Partial Pressures in Alveolar Air and Alveolar Capillaries • Blood arriving in pulmonary arteries has: • Low PO 2 • High PCO 2 • The concentration gradient causes: • O2 to enter blood • CO2 to leave blood • Rapid exchange allows blood and alveolar air to reach equilibrium
  153. 153. © 2012 Pearson Education, Inc. 23-8 Gas Exchange • Partial Pressures in the Systemic Circuit • Oxygenated blood mixes with deoxygenated blood from conducting passageways • Lowers the PO 2 of blood entering systemic circuit (drops to about 95 mm Hg)
  154. 154. © 2012 Pearson Education, Inc. 23-8 Gas Exchange • Partial Pressures in the Systemic Circuit • Interstitial Fluid • PO 2 40 mm Hg • PCO 2 45 mm Hg • Concentration gradient in peripheral capillaries is opposite of lungs • CO2 diffuses into blood • O2 diffuses out of blood
  155. 155. © 2012 Pearson Education, Inc. Figure 23-19a An Overview of Respiratory Processes and Partial Pressures in Respiration Systemic circuit Pulmonary circuit Alveolus Respiratory membrane Pulmonary capillary External Respiration Systemic circuit O = 100P 2 CO2 40=P O = 100P 2 CO2 40=P O = 40P 2 CO2 45=P CO2 O2
  156. 156. © 2012 Pearson Education, Inc. Figure 23-19b An Overview of Respiratory Processes and Partial Pressures in Respiration Internal Respiration Interstitial fluid Systemic capillary O = 95P 2 CO2 40=P CO 2 O 2 Systemic circuit Pulmonary circuit Systemic circuit CO2 45=P O = 40P 2 O = 40P 2 CO2 45=P
  157. 157. © 2012 Pearson Education, Inc. 23-9 Gas Transport • Gas Pickup and Delivery • Blood plasma cannot transport enough O2 or CO2 to meet physiological needs • Red Blood Cells (RBCs) • Transport O2 to, and CO2 from, peripheral tissues • Remove O2 and CO2 from plasma, allowing gases to diffuse into blood
  158. 158. © 2012 Pearson Education, Inc. 23-9 Gas Transport • Oxygen Transport • O2 binds to iron ions in hemoglobin (Hb) molecules • In a reversible reaction • New molecule is called oxyhemoglobin (HbO2) • Each RBC has about 280 million Hb molecules • Each binds four oxygen molecules
  159. 159. © 2012 Pearson Education, Inc. 23-9 Gas Transport • Hemoglobin Saturation • The percentage of heme units in a hemoglobin molecule that contain bound oxygen • Environmental Factors Affecting Hemoglobin • PO 2 of blood • Blood pH • Temperature • Metabolic activity within RBCs
  160. 160. © 2012 Pearson Education, Inc. 23-9 Gas Transport • Oxygen–Hemoglobin Saturation Curve • A graph relating the saturation of hemoglobin to partial pressure of oxygen • Higher PO 2 results in greater Hb saturation • Curve rather than a straight line because Hb changes shape each time a molecule of O2 is bound • Each O2 bound makes next O2 binding easier • Allows Hb to bind O2 when O2 levels are low
  161. 161. © 2012 Pearson Education, Inc. 23-9 Gas Transport • Oxygen Reserves • O2 diffuses • From peripheral capillaries (high PO 2 ) • Into interstitial fluid (low PO 2 ) • Amount of O2 released depends on interstitial PO 2 • Up to 3/4 may be reserved by RBCs
  162. 162. © 2012 Pearson Education, Inc. 23-9 Gas Transport • Carbon Monoxide • CO from burning fuels • Binds strongly to hemoglobin • Takes the place of O2 • Can result in carbon monoxide poisoning
  163. 163. © 2012 Pearson Education, Inc. 23-9 Gas Transport • The Oxygen–Hemoglobin Saturation Curve • Is standardized for normal blood (pH 7.4, 37°C) • When pH drops or temperature rises: • More oxygen is released • Curve shifts to right • When pH rises or temperature drops: • Less oxygen is released • Curve shifts to left
  164. 164. © 2012 Pearson Education, Inc. Figure 23-20 An Oxygen-Hemoglobin Saturation Curve Oxyhemoglobin(%saturation) % saturation of Hb(mm Hg) PO2 10 20 30 40 50 60 70 80 90 100 13.5 35 57 75 83.5 89 92.7 94.5 96.5 97.5 (mm Hg)PO2
  165. 165. © 2012 Pearson Education, Inc. 23-9 Gas Transport • Hemoglobin and pH • Bohr effect is the result of pH on hemoglobin-saturation curve • Caused by CO2 • CO2 diffuses into RBC • An enzyme, called carbonic anhydrase, catalyzes reaction with H2O • Produces carbonic acid (H2CO3) • Dissociates into hydrogen ion (H+ ) and bicarbonate ion (HCO3 − ) • Hydrogen ions diffuse out of RBC, lowering pH
  166. 166. © 2012 Pearson Education, Inc. Figure 23-21a The Effects of pH and Temperature on Hemoglobin Saturation Effect of pH. When the pH drops below normal levels, more oxygen is released; the oxygen–hemoglobin saturation curve shifts to the right. When the pH increases, less oxygen is released; the curve shifts to the left. Oxyhemoglobin(%saturation) 7.6 7.4 7.2 P (mm Hg)O2
  167. 167. © 2012 Pearson Education, Inc. 23-9 Gas Transport • Hemoglobin and Temperature • Temperature increase = hemoglobin releases more oxygen • Temperature decrease = hemoglobin holds oxygen more tightly • Temperature effects are significant only in active tissues that are generating large amounts of heat • For example, active skeletal muscles
  168. 168. © 2012 Pearson Education, Inc. Figure 23-21b The Effects of pH and Temperature on Hemoglobin Saturation Effect of temperature. When the temperature rises, more oxygen is released; the oxygen–hemoglobin saturation curve shifts to the right. 10°C 20°C 38°C 43°C Oxyhemoglobin(%saturation) (mm Hg)PO2
  169. 169. © 2012 Pearson Education, Inc. 23-9 Gas Transport • Hemoglobin and BPG • 2,3-bisphosphoglycerate (BPG) • RBCs generate ATP by glycolysis • Forming lactic acid and BPG • BPG directly affects O2 binding and release • More BPG, more oxygen released
  170. 170. © 2012 Pearson Education, Inc. 23-9 Gas Transport • BPG Levels • BPG levels rise: • When pH increases • When stimulated by certain hormones • If BPG levels are too low: • Hemoglobin will not release oxygen
  171. 171. © 2012 Pearson Education, Inc. 23-9 Gas Transport • Fetal Hemoglobin • The structure of fetal hemoglobin • Differs from that of adult Hb • At the same PO 2 : • Fetal Hb binds more O2 than adult Hb • Which allows fetus to take O2 from maternal blood
  172. 172. © 2012 Pearson Education, Inc. Figure 23-22 A Functional Comparison of Fetal and Adult Hemoglobin Fetal hemoglobin Adult hemoglobin PO2 (mm Hg) Oxyhemoglobin(%saturation)
  173. 173. © 2012 Pearson Education, Inc. 23-9 Gas Transport • Carbon Dioxide Transport (CO2) • Is generated as a by-product of aerobic metabolism (cellular respiration) • CO2 in the bloodstream can be carried three ways 1. Converted to carbonic acid 2. Bound to hemoglobin within red blood cells 3. Dissolved in plasma
  174. 174. © 2012 Pearson Education, Inc. 23-9 Gas Transport • Carbonic Acid Formation • 70% is transported as carbonic acid (H2CO3) • Which dissociates into H+ and bicarbonate (HCO3 − ) • Hydrogen ions bind to hemoglobin • Bicarbonate Ions • Move into plasma by an exchange mechanism (the chloride shift) that takes in Cl− ions without using ATP
  175. 175. © 2012 Pearson Education, Inc. 23-9 Gas Transport • CO2 Binding to Hemoglobin • 23% is bound to amino groups of globular proteins in Hb molecule • Forming carbaminohemoglobin • Transport in Plasma • 7% is transported as CO2 dissolved in plasma
  176. 176. © 2012 Pearson Education, Inc. Figure 23-23 Carbon Dioxide Transport in Blood CO2 diffuses into the bloodstream 93% diffuses into RBCs 23% binds to Hb, forming carbaminohemoglobin, Hb•CO2 H+ removed by buffers, especially Hb 70% converted to H2CO3 by carbonic anhydrase 7% remains dissolved in plasma (as CO2) H2CO3 dissociates into H+ and HCO3 − HCO3 − moves out of RBC in exchange for Cl− (chloride shift) RBC PLASMA
  177. 177. © 2012 Pearson Education, Inc. Figure 23-24 A Summary of the Primary Gas Transport Mechanisms Plasma Red blood cell Alveolar air space O2 pickup Pulmonary capillary O2 delivery Alveolar air space Pulmonary capillary Systemic capillary CO2 delivery Systemic capillary Red blood cell Cells in peripheral tissues Cells in peripheral tissues Chloride shift CO2 pickup
  178. 178. © 2012 Pearson Education, Inc. Figure 23-24 A Summary of the Primary Gas Transport Mechanisms Plasma Red blood cell Alveolar air space O2 pickup Pulmonary capillary
  179. 179. © 2012 Pearson Education, Inc. Figure 23-24 A Summary of the Primary Gas Transport Mechanisms O2 delivery Systemic capillary Red blood cell Cells in peripheral tissues
  180. 180. © 2012 Pearson Education, Inc. Figure 23-24 A Summary of the Primary Gas Transport Mechanisms Alveolar air space Pulmonary capillary CO2 delivery
  181. 181. © 2012 Pearson Education, Inc. Figure 23-24 A Summary of the Primary Gas Transport Mechanisms Systemic capillary Cells in peripheral tissues Chloride shift CO2 pickup
  182. 182. © 2012 Pearson Education, Inc. 23-10 Control of Respiration • Peripheral and Alveolar Capillaries • Maintain balance during gas diffusion by: 1. Changes in blood flow and oxygen delivery 2. Changes in depth and rate of respiration
  183. 183. © 2012 Pearson Education, Inc. 23-10 Control of Respiration • Local Regulation of Gas Transport and Alveolar Function • Rising PCO 2 levels • Relax smooth muscle in arterioles and capillaries • Increase blood flow • Coordination of lung perfusion and alveolar ventilation • Shifting blood flow • PCO 2 levels • Control bronchoconstriction and bronchodilation
  184. 184. © 2012 Pearson Education, Inc. 23-10 Control of Respiration • The Respiratory Centers of the Brain • When oxygen demand rises: • Cardiac output and respiratory rates increase under neural control • Have both voluntary and involuntary components
  185. 185. © 2012 Pearson Education, Inc. 23-10 Control of Respiration • The Respiratory Centers of the Brain • Voluntary centers in cerebral cortex affect: • Respiratory centers of pons and medulla oblongata • Motor neurons that control respiratory muscles • The Respiratory Centers • Three pairs of nuclei in the reticular formation of medulla oblongata and pons • Regulate respiratory muscles • In response to sensory information via respiratory reflexes
  186. 186. © 2012 Pearson Education, Inc. 23-10 Control of Respiration • Respiratory Centers of the Medulla Oblongata • Set the pace of respiration • Can be divided into two groups 1. Dorsal respiratory group (DRG) 2. Ventral respiratory group (VRG)
  187. 187. © 2012 Pearson Education, Inc. 23-10 Control of Respiration • Dorsal Respiratory Group (DRG) • Inspiratory center • Functions in quiet and forced breathing • Ventral Respiratory Group (VRG) • Inspiratory and expiratory center • Functions only in forced breathing
  188. 188. © 2012 Pearson Education, Inc. 23-10 Control of Respiration • Quiet Breathing • Brief activity in the DRG • Stimulates inspiratory muscles • DRG neurons become inactive • Allowing passive exhalation
  189. 189. © 2012 Pearson Education, Inc. Figure 23-25a Basic Regulatory Patterns of Respiration Quiet Breathing INHALATION (2 seconds) Diaphragm and external intercostal muscles contract and inhalation occurs. Dorsal respiratory group inhibited Dorsal respiratory group active Diaphragm and external intercostal muscles relax and passive exhalation occurs. EXHALATION (3 seconds)
  190. 190. © 2012 Pearson Education, Inc. 23-10 Control of Respiration • Forced Breathing • Increased activity in DRG • Stimulates VRG • Which activates accessory inspiratory muscles • After inhalation • Expiratory center neurons stimulate active exhalation
  191. 191. © 2012 Pearson Education, Inc. Figure 23-25b Basic Regulatory Patterns of Respiration INHALATION DRG and inspiratory center of VRG are active. Expiratory center of VRG is inhibited. DRG and inspiratory center of VRG are inhibited. Expiratory center of VRG is active. Forced Breathing Muscles of inhalation contract, and opposing muscles relax Inhalation occurs, EXHALATION Muscles of inhalation relax and muscles of exhalation contract. Exhalation occurs.
  192. 192. © 2012 Pearson Education, Inc. 23-10 Control of Respiration • The Apneustic and Pneumotaxic Centers of the Pons • Paired nuclei that adjust output of respiratory rhythmicity centers • Regulating respiratory rate and depth of respiration • Apneustic Center • Provides continuous stimulation to its DRG center • Pneumotaxic Centers • Inhibit the apneustic centers • Promote passive or active exhalation
  193. 193. © 2012 Pearson Education, Inc. 23-10 Control of Respiration • Respiratory Centers and Reflex Controls • Interactions between VRG and DRG • Establish basic pace and depth of respiration • The pneumotaxic center • Modifies the pace
  194. 194. © 2012 Pearson Education, Inc. Figure 23-26 Control of Respiration Respiratory Centers and Reflex Controls The locations and relationships between the major respiratory centers in the pons and medulla oblongata and other factors important to the reflex control of respiration. Pathways for conscious control over respiratory muscles are not shown. Pneumotaxic center HIGHER CENTERS Cerebral cortex Limbic system Hypothalamus Cerebrum CSF CHEMORECEPTORSPons Apneustic center Medulla oblongata KEY = Stimulation = Inhibition
  195. 195. © 2012 Pearson Education, Inc. Figure 23-26 Control of Respiration KEY = Stimulation = Inhibition Motor neurons controlling other respiratory muscles Respiratory Centers and Reflex Controls N IX and N X Chemoreceptors and baroreceptors of carotid and aortic sinuses Diaphragm Stretch receptors of lungs N X Spinal cord Motor neurons controlling diaphragm Medulla oblongata Respiratory Rhythmicity Centers Dorsal respiratory group (DRG) Ventral respiratory group (VRG) Phrenic nerve
  196. 196. © 2012 Pearson Education, Inc. 23-10 Control of Respiration • Sudden Infant Death Syndrome (SIDS) • Disrupts normal respiratory reflex pattern • May result from connection problems between pacemaker complex and respiratory centers
  197. 197. © 2012 Pearson Education, Inc. 23-10 Control of Respiration • Respiratory Reflexes • Chemoreceptors are sensitive to PCO2 , PO2 , or pH of blood or cerebrospinal fluid • Baroreceptors in aortic or carotid sinuses are sensitive to changes in blood pressure • Stretch receptors respond to changes in lung volume • Irritating physical or chemical stimuli in nasal cavity, larynx, or bronchial tree • Other sensations including pain, changes in body temperature, abnormal visceral sensations
  198. 198. © 2012 Pearson Education, Inc. 23-10 Control of Respiration • The Chemoreceptor Reflexes • Respiratory centers are strongly influenced by chemoreceptor input from: • Glossopharyngeal nerve (N IX) • Vagus nerve (N X) • Central chemoreceptors that monitor cerebrospinal fluid
  199. 199. © 2012 Pearson Education, Inc. 23-10 Control of Respiration • The Chemoreceptor Reflexes • The glossopharyngeal nerve • From carotid bodies • Stimulated by changes in blood pH or PO 2 • The vagus nerve • From aortic bodies • Stimulated by changes in blood pH or PO 2
  200. 200. © 2012 Pearson Education, Inc. 23-10 Control of Respiration • The Chemoreceptor Reflexes • Central chemoreceptors that monitor cerebrospinal fluid • Are on ventrolateral surface of medulla oblongata • Respond to PCO 2 and pH of CSF
  201. 201. © 2012 Pearson Education, Inc. 23-10 Control of Respiration • Chemoreceptor Stimulation • Leads to increased depth and rate of respiration • Is subject to adaptation • Decreased sensitivity due to chronic stimulation
  202. 202. © 2012 Pearson Education, Inc. 23-10 Control of Respiration • Hypercapnia • An increase in arterial PCO 2 • Stimulates chemoreceptors in the medulla oblongata • To restore homeostasis
  203. 203. © 2012 Pearson Education, Inc. 23-10 Control of Respiration • Hypercapnia and Hypocapnia • Hypoventilation is a common cause of hypercapnia • Abnormally low respiration rate • Allows CO2 buildup in blood • Excessive ventilation, hyperventilation, results in abnormally low PCO 2 (hypocapnia) • Stimulates chemoreceptors to decrease respiratory rate
  204. 204. © 2012 Pearson Education, Inc. Figure 23-27a The Chemoreceptor Response to Changes in PCO2 HOMEOSTASIS Normal arterial PCO2 HOMEOSTASIS RESTORED Increased respiratory rate with increased elimination of CO2 at alveoli Stimulation of CSF chemoreceptors at medulla oblongata HOMEOSTASIS DISTURBED Increased PCO2 , decreased pH in CSF Stimulation of arterial chemoreceptors Stimulation of respiratory muscles Start Normal arterial PCO2 Increased arterial PCO2 (hypocapnia) Increased arterial PCO2
  205. 205. © 2012 Pearson Education, Inc. Figure 23-27b The Chemoreceptor Response to Changes in PCO2 HOMEOSTASIS Normal arterial PCO2 Normal arterial PCO2 HOMEOSTASIS RESTORED Start Decreased respiratory rate with decreased elimination of CO2 at alveoli Reduced stimulation of CSF chemoreceptors Inhibition of respiratory muscles Inhibition of arterial chemoreceptors Decreased PCO2 , increased pH in CSF Decreased arterial PCO2 (hypocapnia) HOMEOSTASIS DISTURBED Decreased arterial PCO2
  206. 206. © 2012 Pearson Education, Inc. 23-10 Control of Respiration • The Baroreceptor Reflexes • Carotid and aortic baroreceptor stimulation • Affects blood pressure and respiratory centers • When blood pressure falls: • Respiration increases • When blood pressure increases: • Respiration decreases
  207. 207. © 2012 Pearson Education, Inc. 23-10 Control of Respiration • The Hering−Breuer Reflexes • Two baroreceptor reflexes involved in forced breathing 1. Inflation reflex • Prevents overexpansion of lungs 2. Deflation reflex • Inhibits expiratory centers • Stimulates inspiratory centers during lung deflation
  208. 208. © 2012 Pearson Education, Inc. 23-10 Control of Respiration • Protective Reflexes • Triggered by receptors in epithelium of respiratory tract when lungs are exposed to: • Toxic vapors • Chemical irritants • Mechanical stimulation • Cause sneezing, coughing, and laryngeal spasm
  209. 209. © 2012 Pearson Education, Inc. 23-10 Control of Respiration • Apnea • A period of suspended respiration • Normally followed by explosive exhalation to clear airways • Sneezing and coughing • Laryngeal Spasm • Temporarily closes airway • To prevent foreign substances from entering
  210. 210. © 2012 Pearson Education, Inc. 23-10 Control of Respiration • Voluntary Control of Respiration • Strong emotions can stimulate respiratory centers in hypothalamus • Emotional stress can activate sympathetic or parasympathetic division of ANS • Causing bronchodilation or bronchoconstriction • Anticipation of strenuous exercise can increase respiratory rate and cardiac output by sympathetic stimulation
  211. 211. © 2012 Pearson Education, Inc. 23-10 Control of Respiration • Changes in the Respiratory System at Birth • Before birth • Pulmonary vessels are collapsed • Lungs contain no air • During delivery • Placental connection is lost • Blood PO2 falls • PCO2 rises
  212. 212. © 2012 Pearson Education, Inc. 23-10 Control of Respiration • Changes in the Respiratory System at Birth • At birth • Newborn overcomes force of surface tension to inflate bronchial tree and alveoli and take first breath • Large drop in pressure at first breath • Pulls blood into pulmonary circulation • Closing foramen ovale and ductus arteriosus • Redirecting fetal blood circulation patterns • Subsequent breaths fully inflate alveoli
  213. 213. © 2012 Pearson Education, Inc. 23-11 Effects of Aging on the Respiratory System • Three Effects of Aging on the Respiratory System 1. Elastic tissues deteriorate • Altering lung compliance and lowering vital capacity 2. Arthritic changes • Restrict chest movements • Limit respiratory minute volume 3. Emphysema • Affects individuals over age 50 • Depending on exposure to respiratory irritants (e.g., cigarette smoke)
  214. 214. © 2012 Pearson Education, Inc. Figure 23-28 Decline in Respiratory Performance with Age and Smoking Regular smoker Disability Death Age (years) Stopped at age 65 Stopped at age 45 Never smoked Respiratoryperformance (%ofvalueatage25)
  215. 215. © 2012 Pearson Education, Inc. 23-12 Respiratory System Integration • Respiratory Activity • Maintaining homeostatic O2 and CO2 levels in peripheral tissues requires coordination between several systems • Particularly the respiratory and cardiovascular systems
  216. 216. © 2012 Pearson Education, Inc. 23-12 Respiratory System Integration • Coordination of Respiratory and Cardiovascular Systems • Improves efficiency of gas exchange by controlling lung perfusion • Increases respiratory drive through chemoreceptor stimulation • Raises cardiac output and blood flow through baroreceptor stimulation
  217. 217. © 2012 Pearson Education, Inc. Figure 23-29 System Integrator: The Respiratory System The RESPIRATORY System CardiovascularEndocrineNervousMuscularSkeletal Protects portions of upper respiratory tract; hairs guard entry to external nares Integumentary Body System Respiratory System Respiratory System Body System S Y S T E M I N T E G R A T O R Cardiovascular Page759 Endocrine Page632 Nervous Page543 Muscular Page369 Skeletal Page275 Integumentary Page165Page910Page992 Digestive Page1072 UrinaryReproductive Lymphatic Movements of ribs important in breathing; axial skeleton surrounds and protects lungs Muscular activity generates carbon dioxide; respiratory muscle fill and empty lungs; other muscles control entrances to respiratory tract; intrinsic laryngeal muscles control airflow through larynx and produce sounds Monitors respiratory volume and blood gas levels; controls pace and depth of respiration Epinephrine and norepinephrine stimulate respiratory activity and dilate respiratory passageways Circulates the red blood cells that transport oxygen and carbon dioxide between lungs and peripheral tissues Tonsils protect against infection at entrance to respiratory tract; lymphatic vessels monitor lymph drainage from lungs and mobilize adaptive defenses when infection occurs The respiratory system provides oxygen and eliminates carbon dioxide for our cells. Stabilizing the concentrations of these gases involves a continual exchange of materials with the outside world. The respiratory system is therefore crucial to maintaining homeostasis for all body systems. Page807 Lymphatic Provides oxygen to nourish tissues and removes carbon dioxide Provides oxygen to skeletal structures and disposes of carbon dioxide Provides oxygen needed for muscle contractions and disposs of carbon dioxide generated by active muscles Provides oxygen needed for neural activity and disposes of carbon dioxide Angiotensin-converting enzyme (ACE) from capillaries of lungs converts angiotensin I to angiotensin II Bicarbonate ions contribute to buffering capability of blood; activation of angiotensin II by ACE important in regulation of blood pressure and volume Alveolar phagocytes present antigens to trigger specific defenses; mucous membrane lining the nasal cavity and upper pharynx traps pathogens, protects deeper tissues

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