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  • 1. Chapter 23: The Respiratory System Biol 141 A & P
  • 2. The Respiratory System <ul><li>Cells produce energy: </li></ul><ul><ul><li>for maintenance, growth, defense, and division </li></ul></ul><ul><ul><li>through mechanisms that use oxygen and produce carbon dioxide </li></ul></ul>
  • 3. Oxygen <ul><li>Is obtained from the air by diffusion across delicate exchange surfaces of lungs </li></ul><ul><li>Is carried to cells by the cardiovascular system which also returns carbon dioxide to the lungs </li></ul>3D Movie of Respiratory System PLAY
  • 4. 5 Functions of the Respiratory System <ul><li>Provides extensive gas exchange surface area between air and circulating blood </li></ul><ul><li>Moves air to and from exchange surfaces of lungs </li></ul><ul><li>Protects respiratory surfaces from outside environment </li></ul><ul><li>Produces sounds </li></ul><ul><li>Participates in olfactory sense </li></ul>
  • 5. Components of the Respiratory System Figure 23–1 3D Peel-Away of Respiratory System PLAY
  • 6. Organization of the Respiratory System <ul><li>The respiratory system is divided into the upper respiratory system , above the larynx, and the lower respiratory system , from the larynx down </li></ul>
  • 7. The Respiratory Tract <ul><li>Consists of a conducting portion : </li></ul><ul><ul><li>from nasal cavity to terminal bronchioles </li></ul></ul><ul><li>Consists of a respiratory portion : </li></ul><ul><ul><li>the respiratory bronchioles and alveoli </li></ul></ul><ul><ul><li>Alveoli </li></ul></ul><ul><li>Are air-filled pockets within the lungs </li></ul><ul><ul><li>where all gas exchange takes place </li></ul></ul>The Respiratory Tract PLAY
  • 8. The Respiratory Epithelium Figure 23–2
  • 9. The Respiratory Epithelium <ul><li>For gases to exchange efficiently: </li></ul><ul><ul><li>alveoli walls must be very thin (&lt; 1 µ m) </li></ul></ul><ul><ul><li>surface area must be very great (about 35 times the surface area of the body) </li></ul></ul>
  • 10. The Respiratory Mucosa <ul><li>Consists of: </li></ul><ul><ul><li>an epithelial layer </li></ul></ul><ul><ul><li>an areolar layer </li></ul></ul><ul><li>Lines conducting portion of respiratory system </li></ul>
  • 11. The Lamina Propria <ul><li>Underlies areolar tissue </li></ul><ul><li>In the upper respiratory system, trachea, and bronchi: </li></ul><ul><ul><li>contains mucous glands that secrete onto epithelial surface </li></ul></ul><ul><li>In the conducting portion of lower respiratory system: </li></ul><ul><ul><li>contains smooth muscle cells that encircle lumen of bronchioles </li></ul></ul>
  • 12. Structure of Respiratory Epithelium <ul><li>Changes along respiratory tract </li></ul><ul><li>Alveolar Epithelium </li></ul><ul><li>Is a very delicate, simple squamous epithelium </li></ul><ul><li>Contains scattered and specialized cells </li></ul><ul><li>Lines exchange surfaces of alveoli </li></ul>
  • 13. How are delicate respiratory exchange surfaces protected from pathogens, debris, and other hazards?
  • 14. The Respiratory Defense System <ul><li>Consists of a series of filtration mechanisms </li></ul><ul><li>Removes particles and pathogens </li></ul><ul><li>* Components of the Respiratory Defense System </li></ul><ul><li>Goblet cells and mucous glands : produce mucus that bathes exposed surfaces </li></ul><ul><li>Cilia : sweep debris trapped in mucus toward the pharynx ( mucus escalator ) </li></ul><ul><li>Filtration in nasal cavity removes large particles </li></ul><ul><li>Alveolar macrophages engulf small particles that reach lungs </li></ul>
  • 15. The Upper Respiratory System Figure 23–3
  • 16. The Nose <ul><li>Air enters the respiratory system: </li></ul><ul><ul><li>through nostrils or external nares </li></ul></ul><ul><ul><li>into nasal vestibule </li></ul></ul><ul><li>Nasal hairs : </li></ul><ul><ul><li>are in nasal vestibule </li></ul></ul><ul><ul><li>are the first particle filtration system </li></ul></ul>
  • 17. The Nasal Cavity <ul><li>The nasal septum : </li></ul><ul><ul><li>divides nasal cavity into left and right </li></ul></ul><ul><li>Mucous secretions from paranasal sinus and tears: </li></ul><ul><ul><li>clean and moisten the nasal cavity </li></ul></ul><ul><li>Superior portion of nasal cavity is the olfactory region : </li></ul><ul><ul><li>provides sense of smell </li></ul></ul>
  • 18. Air Flow <ul><li>From vestibule to internal nares : </li></ul><ul><ul><li>through superior , middle, and inferior meatuses </li></ul></ul><ul><ul><li>Meatuses </li></ul></ul><ul><li>Constricted passageways that produce air turbulence: </li></ul><ul><ul><li>warm and humidify incoming air </li></ul></ul><ul><ul><li>trap particles </li></ul></ul>
  • 19. The Palates <ul><li>Hard palate : </li></ul><ul><ul><li>forms floor of nasal cavity </li></ul></ul><ul><ul><li>separates nasal and oral cavities </li></ul></ul><ul><li>Soft palate : </li></ul><ul><ul><li>extends posterior to hard palate </li></ul></ul><ul><ul><li>divides superior nasopharynx from lower pharynx </li></ul></ul>
  • 20. Air Flow <ul><li>Nasal cavity opens into nasopharynx through internal nares </li></ul><ul><li>The Nasal Mucosa </li></ul><ul><li>Warm and humidify inhaled air for arrival at lower respiratory organs </li></ul><ul><li>Breathing through mouth bypasses this important step </li></ul>
  • 21. The Pharynx and Divisions <ul><li>A chamber shared by digestive and respiratory systems </li></ul><ul><li>Extends from internal nares to entrances to larynx and esophagus </li></ul><ul><li>Nasopharynx </li></ul><ul><li>Oropharynx </li></ul><ul><li>Laryngopharynx </li></ul>
  • 22. The Nasopharynx <ul><li>Superior portion of the pharynx </li></ul><ul><li>Contains pharyngeal tonsils and openings to left and right auditory tubes </li></ul><ul><li>The Oropharynx </li></ul><ul><li>Middle portion of the pharynx </li></ul><ul><li>Communicates with oral cavity </li></ul><ul><li>The Laryngopharynx </li></ul><ul><li>Inferior portion of the pharynx </li></ul><ul><li>Extends from hyoid bone to entrance to larynx and esophagus </li></ul>
  • 23. What is the structure of the larynx and its role in normal breathing and production of sound?
  • 24. Anatomy of the Larynx Figure 23–4 <ul><li>Air Flow- </li></ul><ul><li>From the pharynx enters the larynx : </li></ul><ul><ul><li>a cartilaginous structure that surrounds the glottis </li></ul></ul>
  • 25. Cartilages of the Larynx <ul><li>3 large, unpaired cartilages form the larynx : </li></ul><ul><ul><li>the thyroid cartilage </li></ul></ul><ul><ul><li>the cricoid cartilage </li></ul></ul><ul><ul><li>the epiglottis </li></ul></ul>
  • 26. The Thyroid Cartilage <ul><li>Also called the Adam’s apple </li></ul><ul><li>Is a hyaline cartilage </li></ul><ul><li>Forms anterior and lateral walls of larynx </li></ul><ul><li>Ligaments attach to hyoid bone, epiglottis, and laryngeal cartilages </li></ul>
  • 27. The Cricoid Cartilage <ul><li>Is a hyaline cartilage </li></ul><ul><li>Form posterior portion of larynx </li></ul><ul><li>Ligaments attach to first tracheal cartilage </li></ul><ul><li>Articulates with arytenoid cartilages </li></ul><ul><li>The Epiglottis </li></ul><ul><li>Composed of elastic cartilage </li></ul><ul><li>Ligaments attach to thyroid cartilage and hyoid bone </li></ul>
  • 28. Cartilage Functions <ul><li>Thyroid and cricoid cartilages support and protect: </li></ul><ul><ul><li>the glottis </li></ul></ul><ul><ul><li>the entrance to trachea </li></ul></ul><ul><li>During swallowing: </li></ul><ul><ul><li>the larynx is elevated </li></ul></ul><ul><ul><li>the epiglottis folds back over glottis </li></ul></ul><ul><li>Prevents entry of food and liquids into respiratory tract </li></ul>
  • 29. The Glottis Figure 23–5 <ul><li>3 pairs of Small Hyaline Cartilages of the Larynx </li></ul><ul><li>arytenoid cartilages, corniculate cartilages </li></ul><ul><ul><li>cuneiform cartilages </li></ul></ul>
  • 30. Cartilage Functions <ul><li>Corniculate and arytenoid cartilages function in: </li></ul><ul><ul><li>opening and closing of glottis </li></ul></ul><ul><ul><li>production of sound </li></ul></ul>
  • 31. Ligaments of the Larynx <ul><li>Vestibular ligaments and vocal ligaments : </li></ul><ul><ul><li>extend between thyroid cartilage and arytenoid cartilages </li></ul></ul><ul><ul><li>are covered by folds of laryngeal epithelium that project into glottis </li></ul></ul><ul><ul><li>1) The Vestibular Ligaments </li></ul></ul><ul><li>Lie within vestibular folds : </li></ul><ul><ul><li>which protect delicate vocal folds </li></ul></ul>
  • 32. Sound Production <ul><li>Air passing through glottis: </li></ul><ul><ul><li>vibrates vocal folds </li></ul></ul><ul><ul><li>produces sound waves </li></ul></ul><ul><ul><li> Sound Variation </li></ul></ul><ul><li>Sound is varied by: </li></ul><ul><ul><li>tension on vocal folds: slender and short =high pitched, thicker and longer = low pitched </li></ul></ul><ul><ul><li>voluntary muscles (position arytenoid cartilage relative to thyroid cartilage) </li></ul></ul>
  • 33. Speech <ul><li>Is produced by: </li></ul><ul><ul><li>phonation : </li></ul></ul><ul><ul><ul><li>sound production at the larynx </li></ul></ul></ul><ul><ul><li>articulation : </li></ul></ul><ul><ul><ul><li>modification of sound by other structures </li></ul></ul></ul>
  • 34. The Laryngeal Musculature <ul><li>The larynx is associated with: </li></ul><ul><ul><li>muscles of neck and pharynx </li></ul></ul><ul><ul><li>intrinsic muscles that: </li></ul></ul><ul><ul><ul><li>control vocal folds </li></ul></ul></ul><ul><ul><ul><li>open and close glottis </li></ul></ul></ul><ul><ul><ul><li>Coughing reflex: food or liquids went “down the wrong pipe” </li></ul></ul></ul>
  • 35. Anatomy of the Trachea Figure 23–6 What is the structure of airways outside the lungs?
  • 36. The Trachea <ul><li>Also called the windpipe </li></ul><ul><li>Extends from the cricoid cartilage into mediastinum </li></ul><ul><ul><li>where it branches into right and left pulmonary bronchi </li></ul></ul><ul><ul><li>The Submucosa </li></ul></ul><ul><ul><li>Beneath mucosa of trachea </li></ul></ul><ul><li>Contains mucous glands </li></ul>
  • 37. The Tracheal Cartilages <ul><li>15–20 tracheal cartilages : </li></ul><ul><ul><li>strengthen and protect airway </li></ul></ul><ul><ul><li>discontinuous where trachea contacts esophagus </li></ul></ul><ul><li>Ends of each tracheal cartilage are connected by: </li></ul><ul><ul><li>an elastic ligament and trachealis muscle </li></ul></ul>
  • 38. The Primary Bronchi <ul><li>Right and left primary bronchi : </li></ul><ul><ul><li>separated by an internal ridge (the carina ) </li></ul></ul><ul><ul><li>1) The Right Primary Bronchus </li></ul></ul><ul><li>Is larger in diameter than the left </li></ul><ul><li>Descends at a steeper angle </li></ul>
  • 39. Structure of Primary Bronchi <ul><li>Each primary bronchus: </li></ul><ul><ul><li>travels to a groove ( hilus ) along medial surface of the lung </li></ul></ul><ul><ul><li>Hilus- </li></ul></ul><ul><li>Where pulmonary nerves, blood vessels, and lymphatics enter lung </li></ul><ul><li>Anchored in meshwork of connective tissue </li></ul>
  • 40. The Root of the Lung <ul><li>Complex of connective tissues, nerves, and vessels in hilus: </li></ul><ul><ul><li>anchored to the mediastinum </li></ul></ul>
  • 41. Gross Anatomy of the Lungs Figure 23–7 <ul><li>Left and right lungs : </li></ul><ul><ul><li>are in left and right pleural cavities </li></ul></ul><ul><li>The base : </li></ul><ul><ul><li>inferior portion of each lung rests on superior surface of diaphragm </li></ul></ul>
  • 42. Lobes of the Lungs <ul><li>Lungs have lobes separated by deep fissures </li></ul><ul><li>1) The Right Lung- Has 3 lobes: </li></ul><ul><ul><li>superior, middle, and inferior </li></ul></ul><ul><ul><li>separated by horizontal and oblique fissures </li></ul></ul><ul><ul><li>2) The Left Lung- Has 2 lobes: </li></ul></ul><ul><ul><li>superior and inferior </li></ul></ul><ul><ul><li>are separated by an oblique fissure </li></ul></ul>
  • 43. Relationship between Lungs and Heart Figure 23–8
  • 44. Lung Shape <ul><li>Right lung: </li></ul><ul><ul><li>is wider </li></ul></ul><ul><ul><li>is displaced upward by liver </li></ul></ul><ul><li>Left lung: </li></ul><ul><ul><li>is longer </li></ul></ul><ul><ul><li>is displaced leftward by the heart forming the cardiac notch </li></ul></ul>
  • 45. The Bronchial Tree <ul><li>Is formed by the primary bronchi and their branches </li></ul><ul><li>Extrapulmonary Bronchi </li></ul><ul><li>The left and right bronchi branches outside the lungs </li></ul><ul><li>Intrapulmonary Bronchi </li></ul><ul><li>Branches within the lungs </li></ul>
  • 46. Bronchi and Lobules Figure 23–9 A Primary Bronchus Branches to form secondary bronchi (lobar bronchi) 1 secondary bronchus goes to each lobe
  • 47. Secondary Bronchi <ul><li>Branch to form tertiary bronchi , also called the segmental bronchi </li></ul><ul><li>Each segmental bronchus : </li></ul><ul><ul><li>supplies air to a single bronchopulmonary segment- </li></ul></ul><ul><ul><li>The right lung has 10 </li></ul></ul><ul><ul><li>The left lung has 8 or 9 </li></ul></ul>
  • 48. Bronchial Structure <ul><li>The walls of primary, secondary, and tertiary bronchi: </li></ul><ul><ul><li>contain progressively less cartilage and more smooth muscle </li></ul></ul><ul><ul><li>increasing muscular effects on airway constriction and resistance </li></ul></ul>
  • 49. The Bronchioles Figure 23–10 Bronchitis: Inflammation of bronchial walls: causes constriction and breathing difficulty
  • 50. The Bronchioles <ul><li>Each tertiary bronchus branches into multiple bronchioles </li></ul><ul><li>Bronchioles branch into terminal bronchioles: </li></ul><ul><ul><li>1 tertiary bronchus forms about 6500 terminal bronchioles </li></ul></ul>
  • 51. Bronchiole Structure <ul><li>Bronchioles: </li></ul><ul><ul><li>have no cartilage </li></ul></ul><ul><ul><li>are dominated by smooth muscle </li></ul></ul><ul><ul><li>Autonomic Control </li></ul></ul><ul><li>Regulates smooth muscle: </li></ul><ul><ul><li>controls diameter of bronchioles </li></ul></ul><ul><ul><li>controls airflow and resistance in lungs </li></ul></ul>
  • 52. Bronchodilation <ul><li>Dilation of bronchial airways </li></ul><ul><li>Caused by sympathetic ANS activation </li></ul><ul><li>Reduces resistance </li></ul><ul><li>Bronchoconstriction </li></ul><ul><li>Constricts bronchi </li></ul><ul><li>Caused by: </li></ul><ul><ul><li>parasympathetic ANS activation </li></ul></ul><ul><ul><li>histamine release (allergic reactions) </li></ul></ul>
  • 53. Asthma <ul><li>Excessive stimulation and bronchoconstriction </li></ul><ul><li>Stimulation severely restricts airflow </li></ul>
  • 54. Pulmonary Lobules <ul><li>Are the smallest compartments of the lung </li></ul><ul><li>Are divided by the smallest trabecular partitions ( interlobular septa ) </li></ul><ul><li>Each terminal bronchiole delivers air to a single pulmonary lobule </li></ul><ul><li>Each pulmonary lobule is supplied by pulmonary arteries and veins </li></ul>
  • 55. Exchange Surfaces <ul><li>Within the lobule: </li></ul><ul><ul><li>each terminal bronchiole branches to form several respiratory bronchioles , where gas exchange takes place </li></ul></ul>
  • 56. Alveolar Organization Figure 23–11 <ul><li>Respiratory bronchioles are connected to alveoli along alveolar ducts </li></ul><ul><li>Alveolar ducts end at alveolar sacs: </li></ul><ul><ul><li>common chambers connected to many individual alveoli </li></ul></ul>
  • 57. An Alveolus <ul><li>Has an extensive network of capillaries </li></ul><ul><li>Is surrounded by elastic fibers </li></ul><ul><li>Alveolar Epithelium </li></ul><ul><li>Consists of simple squamous epithelium </li></ul><ul><li>Consists of thin, delicate Type I cells </li></ul><ul><li>Patrolled by alveolar macrophages , also called dust cells </li></ul><ul><li>Contains septal cells ( Type II cells ) that produce Surfactant- an oily secretion which </li></ul><ul><li>1) Contains phospholipids and proteins </li></ul><ul><li>2) Coats alveolar surfaces and reduces surface tension </li></ul>
  • 58. Respiratory Distress <ul><li>Difficult respiration: </li></ul><ul><ul><li>due to alveolar collapse </li></ul></ul><ul><ul><li>caused when septal cells do not produce enough surfactant </li></ul></ul>
  • 59. Respiratory Membrane - The thin membrane of alveoli where gas exchange takes place <ul><li>3 Parts of the Respiratory Membrane </li></ul><ul><li>Squamous epithelial lining of alveolus </li></ul><ul><li>Endothelial cells lining an adjacent capillary </li></ul><ul><li>Fused basal laminae between alveolar and endothelial cells </li></ul><ul><li>Diffusion- Across respiratory membrane is very rapid: </li></ul><ul><ul><li>because distance is small </li></ul></ul><ul><ul><li>gases (O 2 and CO 2 ) are lipid soluble </li></ul></ul>
  • 60. Inflammation of Lobules <ul><li>Also called pneumonia : </li></ul><ul><ul><li>causes fluid to leak into alveoli </li></ul></ul><ul><ul><li>compromises function of respiratory membrane </li></ul></ul>
  • 61. Blood Supply to Respiratory Surfaces <ul><li>Each lobule receives an arteriole and a venule </li></ul><ul><ul><li>respiratory exchange surfaces receive blood: </li></ul></ul><ul><ul><ul><li>from arteries of pulmonary circuit </li></ul></ul></ul><ul><ul><li>a capillary network surrounds each alveolus: </li></ul></ul><ul><ul><ul><li>as part of the respiratory membrane </li></ul></ul></ul><ul><ul><li>blood from alveolar capillaries: </li></ul></ul><ul><ul><ul><li>passes through pulmonary venules and veins </li></ul></ul></ul><ul><ul><ul><li>returns to left atrium </li></ul></ul></ul>
  • 62. Blood Supply to the Lungs <ul><li>Capillaries supplied by bronchial arteries: </li></ul><ul><ul><li>provide oxygen and nutrients to tissues of conducting passageways of lung </li></ul></ul><ul><li>Venous blood bypasses the systemic circuit and flows into pulmonary veins </li></ul>
  • 63. Blood Pressure <ul><li>In pulmonary circuit is low (30 mm Hg) </li></ul><ul><li>Pulmonary vessels are easily blocked by blood clots, fat, or air bubbles, causing pulmonary embolism </li></ul>
  • 64. Pleural Cavities and Pleural Membranes Figure 23–8
  • 65. Pleural Cavities and Pleural Membranes <ul><li>2 pleural cavities : </li></ul><ul><ul><li>are separated by the mediastinum </li></ul></ul><ul><li>Each pleural cavity: </li></ul><ul><ul><li>holds a lung </li></ul></ul><ul><ul><li>is lined with a serous membrane (the pleura ) </li></ul></ul><ul><li>Pleura consist of 2 layers: </li></ul><ul><ul><li>parietal pleura </li></ul></ul><ul><ul><li>visceral pleura </li></ul></ul><ul><li>Pleural fluid : </li></ul><ul><ul><li>lubricates space between 2 layers </li></ul></ul>
  • 66. Respiration <ul><li>Refers to 2 integrated processes: </li></ul><ul><ul><li>External respiration- Includes all processes involved in exchanging O 2 and CO 2 with the environment </li></ul></ul><ul><ul><li>Internal respiration- Also called cellular respiration </li></ul></ul><ul><li>Involves the uptake of O 2 and production of CO 2 within individual cells </li></ul>
  • 67. 3 Processes of External Respiration <ul><li>Pulmonary ventilation (breathing) </li></ul><ul><li>Gas diffusion : </li></ul><ul><ul><li>across membranes and capillaries </li></ul></ul><ul><li>Transport of O 2 and CO 2 : </li></ul><ul><ul><li>between alveolar capillaries </li></ul></ul><ul><ul><li>between capillary beds in other tissues </li></ul></ul>
  • 68. What physical principles govern the movement of air into the lungs?
  • 69. Pulmonary Ventilation <ul><li>Is the physical movement of air in and out of respiratory tract </li></ul><ul><li>Provides alveolar ventilation </li></ul>InterActive Physiology: Respiratory System: Anatomy Review: Respiratory Structures PLAY
  • 70. Gas Pressure and Volume Figure 23–13 Atmospheric Pressure <ul><li>The weight of air: </li></ul><ul><ul><li>has several important physiological effects </li></ul></ul>
  • 71. Boyle’s Law <ul><li>Defines the relationship between gas pressure and volume: </li></ul><ul><li>P = 1/V </li></ul><ul><li>In a contained gas: </li></ul><ul><ul><li>external pressure forces molecules closer together </li></ul></ul><ul><ul><li>movement of gas molecules exerts pressure on container </li></ul></ul>
  • 72. Mechanisms of Pulmonary Ventilation Respiration: Pressure Gradients PLAY Figure 23–14 <ul><li>Pressure Difference </li></ul><ul><li>Air flows from area of higher pressure to area of lower pressure </li></ul>
  • 73. A Respiratory Cycle <ul><li>Consists of: </li></ul><ul><ul><li>an inspiration (inhalation) </li></ul></ul><ul><ul><li>an expiration (exhalation) </li></ul></ul><ul><ul><li>Respiration </li></ul></ul><ul><li>Causes volume changes that create changes in pressure </li></ul><ul><li>Volume of thoracic cavity changes: </li></ul><ul><ul><li>with expansion or contraction of diaphragm or rib cage </li></ul></ul>
  • 74. Compliance of the Lung <ul><li>An indicator of expandability </li></ul><ul><li>Low compliance requires greater force </li></ul><ul><li>High compliance requires less force </li></ul><ul><li>Factors That Affect Compliance </li></ul><ul><li>Connective-tissue structure of the lungs </li></ul><ul><li>Level of surfactant production </li></ul><ul><li>Mobility of the thoracic cage </li></ul>
  • 75. Pressure and Volume Changes with Inhalation and Exhalation Figure 23–15 <ul><li>Can be measured inside or outside the lungs </li></ul><ul><li>Normal atmospheric pressure: </li></ul><ul><ul><li>1 atm or Patm at sea level: 760 mm Hg </li></ul></ul>
  • 76. Intrapulmonary Pressure <ul><li>Also called intra-alveolar pressure </li></ul><ul><li>Is relative to P atm </li></ul><ul><li>In relaxed breathing, the difference between P atm and intrapulmonary pressure is small: </li></ul><ul><ul><li>about —1 mm Hg on inhalation or +1 mm Hg on expiration </li></ul></ul>
  • 77. Maximum Intrapulmonary Pressure <ul><li>Maximum straining, a dangerous activity, can increase range: </li></ul><ul><ul><li>from —30 mm Hg to +100 mm Hg </li></ul></ul>
  • 78. Intrapleural Pressure <ul><li>Pressure in space between parietal and visceral pleura </li></ul><ul><li>Averages —4 mm Hg </li></ul><ul><li>Maximum of —18 mm Hg </li></ul><ul><li>Remains below P atm throughout respiratory cycle </li></ul>
  • 79. The Respiratory Pump <ul><li>Cyclical changes in intrapleural pressure operate the respiratory pump: </li></ul><ul><ul><li>which aids in venous return to heart </li></ul></ul><ul><ul><li>Tidal Volume </li></ul></ul><ul><li>Amount of air moved in and out of lungs in a single respiratory cycle </li></ul>
  • 80. Injury to the Chest Wall <ul><li>Pneumothorax: </li></ul><ul><ul><li>allows air into pleural cavity </li></ul></ul><ul><li>Atelectasis: </li></ul><ul><ul><li>also called a collapsed lung </li></ul></ul><ul><ul><li>result of pneumothorax </li></ul></ul>
  • 81. What are the origins and actions of the respiratory muscles responsible for respiratory movements?
  • 82. The Respiratory Muscles Figure 23–16a, b <ul><li>Most important are: </li></ul><ul><ul><li>the diaphragm </li></ul></ul><ul><ul><li>external intracostal muscles of the ribs </li></ul></ul><ul><ul><li>accessory respiratory muscles : </li></ul></ul><ul><ul><ul><li>activated when respiration increases significantly </li></ul></ul></ul>
  • 83. The Respiratory Muscles Figure 23–16c, d
  • 84. The Mechanics of Breathing <ul><li>Inhalation: </li></ul><ul><ul><li>always active </li></ul></ul><ul><li>Exhalation: </li></ul><ul><ul><li>active or passive </li></ul></ul>
  • 85. 3 Muscle Groups of Inhalation <ul><li>Diaphragm: </li></ul><ul><ul><li>contraction draws air into lungs </li></ul></ul><ul><ul><li>75% of normal air movement </li></ul></ul><ul><li>External intracostal muscles: </li></ul><ul><ul><li>assist inhalation </li></ul></ul><ul><ul><li>25% of normal air movement </li></ul></ul><ul><li>Accessory muscles assist in elevating ribs: </li></ul><ul><ul><li>sternocleidomastoid </li></ul></ul><ul><ul><li>serratus anterior </li></ul></ul><ul><ul><li>pectoralis minor </li></ul></ul><ul><ul><li>scalene muscles </li></ul></ul>
  • 86. Muscles of Active Exhalation <ul><li>Internal intercostal and transversus thoracis muscles: </li></ul><ul><ul><li>depress the ribs </li></ul></ul><ul><li>Abdominal muscles: </li></ul><ul><ul><li>compress the abdomen </li></ul></ul><ul><ul><li>force diaphragm upward </li></ul></ul>
  • 87. Modes of Breathing <ul><li>Respiratory movements are classified: </li></ul><ul><ul><li>by pattern of muscle activity </li></ul></ul><ul><ul><li>into quiet breathing and forced breathing </li></ul></ul>
  • 88. Quiet Breathing (Eupnea) <ul><li>Involves active inhalation and passive exhalation </li></ul><ul><li>Diaphragmatic breathing or deep breathing : </li></ul><ul><ul><li>is dominated by diaphragm </li></ul></ul><ul><li>Costal breathing or shallow breathing : </li></ul><ul><ul><li>is dominated by ribcage movements </li></ul></ul><ul><ul><li>Elastic Rebound </li></ul></ul><ul><li>When inhalation muscles relax: </li></ul><ul><ul><li>elastic components of muscles and lungs recoil </li></ul></ul><ul><ul><li>returning lungs and alveoli to original position </li></ul></ul>
  • 89. Forced Breathing <ul><li>Also called hyperpnea </li></ul><ul><li>Involves active inhalation and exhalation </li></ul><ul><li>Assisted by accessory muscles </li></ul><ul><li>Maximum levels occur in exhaustion </li></ul>
  • 90. Respiratory Rates and Volumes <ul><li>Respiratory system adapts to changing oxygen demands by varying: </li></ul><ul><ul><li>the number of breaths per minute ( respiratory rate ) </li></ul></ul><ul><ul><li>the volume of air moved per breath ( tidal volume ) </li></ul></ul>
  • 91. Respiratory Minute Volume <ul><li>Amount of air moved per minute </li></ul><ul><li>Is calculated by: </li></ul><ul><ul><li>respiratory rate  tidal volume </li></ul></ul><ul><li>Measures pulmonary ventilation </li></ul><ul><li>Anatomic Dead Space </li></ul><ul><li>Only a part of respiratory minute volume reaches alveolar exchange surfaces </li></ul><ul><li>Volume of air remaining in conducting passages is anatomic dead space </li></ul>
  • 92. Alveolar Ventilation <ul><li>Amount of air reaching alveoli each minute </li></ul><ul><li>Calculated as: </li></ul><ul><ul><li>tidal volume — anatomic dead space  respiratory rate </li></ul></ul><ul><li>Alveoli contain less O 2 , more CO 2 than atmospheric air: </li></ul><ul><ul><li>because air mixes with exhaled air </li></ul></ul>
  • 93. Alveolar Ventilation Rate <ul><li>Determined by respiratory rate and tidal volume: </li></ul><ul><ul><li>for a given respiratory rate: </li></ul></ul><ul><ul><ul><li>increasing tidal volume increases alveolar ventilation rate </li></ul></ul></ul><ul><ul><li>for a given tidal volume: </li></ul></ul><ul><ul><ul><li>increasing respiratory rate increases alveolar ventilation </li></ul></ul></ul>
  • 94. Respiratory Volumes and Capacities Figure 23–17
  • 95. Lung Volume <ul><li>Total lung volume is divided into a series of volumes and capacities useful in diagnosis </li></ul><ul><li>Pulmonary Function Tests </li></ul><ul><li>Measure rates and volumes of air movements </li></ul>
  • 96. 4 Pulmonary Volumes <ul><li>Resting tidal volume: </li></ul><ul><ul><li>in a normal respiratory cycle </li></ul></ul><ul><li>Expiratory reserve volume (ERV): </li></ul><ul><ul><li>after a normal exhalation </li></ul></ul><ul><li>Residual volume: </li></ul><ul><ul><li>after maximal exhalation </li></ul></ul><ul><ul><li>minimal volume (in a collapsed lung) </li></ul></ul><ul><li>Inspiratory reserve volume (IRV): </li></ul><ul><ul><li>after a normal inspiration </li></ul></ul>
  • 97. 4 Calculated Respiratory Capacities <ul><li>Inspiratory capacity: </li></ul><ul><ul><li>tidal volume + inspiratory reserve volume </li></ul></ul><ul><li>Functional residual capacity (FRC): </li></ul><ul><ul><li>expiratory reserve volume + residual volume </li></ul></ul><ul><li>Vital capacity: </li></ul><ul><ul><li>expiratory reserve volume + tidal volume + inspiratory reserve volume </li></ul></ul><ul><li>Total lung capacity: </li></ul><ul><li> vital capacity + residual volume </li></ul>
  • 98. Gas Exchange <ul><li>Occurs between blood and alveolar air </li></ul><ul><li>Across the respiratory membrane </li></ul><ul><li>Depends on: </li></ul><ul><ul><li>partial pressures of the gases </li></ul></ul><ul><ul><li>diffusion of molecules between gas and liquid </li></ul></ul>InterActive Physiology: Respiratory System: Gas Exchange PLAY
  • 99. The Gas Laws <ul><li>Diffusion occurs in response to concentration gradients </li></ul><ul><li>Rate of diffusion depends on physical principles, or gas laws </li></ul><ul><ul><li>e.g., Boyle’s law </li></ul></ul>
  • 100. Composition of Air <ul><li>Nitrogen (N 2 ) about 78.6% </li></ul><ul><li>Oxygen (O 2 ) about 20.9% </li></ul><ul><li>Water vapor (H 2 O) about 0.5% </li></ul><ul><li>Carbon dioxide (CO 2 ) about 0.04% </li></ul>
  • 101. Gas Pressure <ul><li>Atmospheric pressure (760 mm Hg): </li></ul><ul><ul><li>produced by air molecules bumping into each other </li></ul></ul><ul><li>Each gas contributes to the total pressure: </li></ul><ul><ul><li>in proportion to its number of molecules ( Dalton’s law ) </li></ul></ul>
  • 102. Partial Pressure <ul><li>The pressure contributed by each gas in the atmosphere </li></ul><ul><li>All partial pressures together add up to 760 mm Hg </li></ul>
  • 103. Henry’s Law Figure 23–18 <ul><li>When gas under pressure comes in contact with liquid: </li></ul><ul><ul><li>gas dissolves in liquid until equilibrium is reached </li></ul></ul><ul><li>At a given temperature: </li></ul><ul><ul><li>amount of a gas in solution is proportional to partial pressure of that gas </li></ul></ul>
  • 104. Gas Content &amp; Solubility in body fluids <ul><li>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 </li></ul><ul><li>CO 2 is very soluble </li></ul><ul><li>O 2 is less soluble </li></ul><ul><li>N 2 has very low solubility </li></ul>
  • 105. Diffusion and the Respiratory Membrane <ul><li>Direction and rate of diffusion of gases across the respiratory membrane determine different partial pressures and solubilities </li></ul>
  • 106. Efficiency of Gas Exchange <ul><li>Due to: </li></ul><ul><ul><li>– substantial differences in partial pressure across the respiratory membrane </li></ul></ul><ul><ul><li>– distances involved in gas exchange are small </li></ul></ul><ul><ul><li>O 2 and CO 2 are lipid soluble </li></ul></ul><ul><ul><li>– total surface area is large </li></ul></ul><ul><ul><li>– blood flow and air flow are coordinated </li></ul></ul>
  • 107. Respiratory Processes and Partial Pressure Figure 23–19 An Overview of Respiratory Processes and Partial Pressures in Respiration PLAY <ul><li>Normal Partial Pressures </li></ul><ul><li>In pulmonary vein plasma: </li></ul><ul><ul><li>PCO2 = 40 mm Hg </li></ul></ul><ul><ul><li>PO2 = 100 mm Hg </li></ul></ul><ul><ul><li>PN2 = 573 mm Hg </li></ul></ul>
  • 108. O 2 and CO 2 <ul><li>Blood arriving in pulmonary arteries has: </li></ul><ul><ul><li>low P O 2 </li></ul></ul><ul><ul><li>high P CO 2 </li></ul></ul><ul><li>The concentration gradient causes: </li></ul><ul><ul><li>O 2 to enter blood </li></ul></ul><ul><ul><li>CO 2 to leave blood </li></ul></ul><ul><li>Rapid exchange allows blood and alveolar air to reach equilibrium </li></ul>
  • 109. Mixing <ul><li>Oxygenated blood mixes with unoxygenated blood from conducting passageways </li></ul><ul><li>Lowers the PO 2 of blood entering systemic circuit (about 95 mm Hg) </li></ul>Respiration: Gas Mixture in Air PLAY
  • 110. Interstitial Fluid <ul><li>P O 2 40 mm Hg </li></ul><ul><li>P CO 2 45 mm Hg </li></ul><ul><li>Concentration gradient in peripheral capillaries is opposite of lungs: </li></ul><ul><ul><li>CO 2 diffuses into blood </li></ul></ul><ul><ul><li>O 2 diffuses out of blood </li></ul></ul>
  • 111. How is oxygen picked up, transported, and released in the blood? What is the structure and function of hemoglobin?
  • 112. Gas Pickup and Delivery <ul><li>Blood plasma can’t transport enough O 2 or CO 2 to meet physiological needs </li></ul><ul><li>Red Blood Cells ( RBCs ) </li></ul><ul><li>Transport O 2 to, and CO 2 from, peripheral tissues </li></ul><ul><li>Remove O 2 and CO 2 from plasma, allowing gases to diffuse into blood </li></ul>
  • 113. Oxygen Transport <ul><li>O 2 binds to iron ions in hemoglobin (Hb) molecules: </li></ul><ul><ul><li>in a reversible reaction </li></ul></ul><ul><li>Each RBC has about 280 million Hb molecules: </li></ul><ul><ul><li>each binds 4 oxygen molecules -saturated </li></ul></ul><ul><li>The percentage of heme units in a hemoglobin molecule: </li></ul><ul><ul><li>that contain bound oxygen </li></ul></ul>Respiration: Oxygen and Carbon Dioxide Transport PLAY
  • 114. Oxyhemoglobin Saturation Curve Figure 23–20 (Navigator) Environmental Factors Affecting Hemoglobin PO2 of blood, Blood pH, Temperature Metabolic activity within RBCs
  • 115. Oxyhemoglobin Saturation Curve <ul><li>Is a graph relating the saturation of hemoglobin to partial pressure of oxygen: </li></ul><ul><ul><li>higher P O 2 results in greater Hb saturation </li></ul></ul><ul><li>Is a curve rather than a straight line: </li></ul><ul><ul><li>because Hb changes shape each time a molecule of O 2 is bound </li></ul></ul><ul><ul><li>each O 2 bound makes next O 2 binding easier </li></ul></ul><ul><ul><li>allows Hb to bind O 2 when O 2 levels are low </li></ul></ul>
  • 116. Oxygen Reserves <ul><li>O 2 diffuses: </li></ul><ul><ul><li>from peripheral capillaries (high PO 2 ) </li></ul></ul><ul><ul><li>into interstitial fluid (low PO 2 ) </li></ul></ul><ul><li>Amount of O 2 released depends on interstitial PO 2 </li></ul><ul><li>Up to 3/4 may be reserved by RBCs </li></ul><ul><li> Carbon Monoxide </li></ul><ul><li>CO from burning fuels: </li></ul><ul><ul><li>binds strongly to hemoglobin </li></ul></ul><ul><ul><li>takes the place of O 2 </li></ul></ul><ul><ul><li>can result in carbon monoxide poisoning </li></ul></ul>
  • 117. pH, Temperature, and Hemoglobin Saturation Figure 23–21
  • 118. The Oxyhemoglobin Saturation Curve <ul><li>Is standardized for normal blood (pH 7.4, 37°C) </li></ul><ul><li>When pH drops or temperature rises: </li></ul><ul><ul><li>more oxygen is released </li></ul></ul><ul><ul><li>curve shift to right </li></ul></ul><ul><li>When pH rises or temperature drops: </li></ul><ul><ul><li>less oxygen is released </li></ul></ul><ul><ul><li>curve shifts to left </li></ul></ul>
  • 119. The Bohr Effect <ul><li>Is the effect of pH on hemoglobin saturation curve </li></ul><ul><li>Caused by CO 2 : </li></ul><ul><ul><li>CO 2 diffuses into RBC </li></ul></ul><ul><ul><li>an enzyme, called carbonic anhydrase, catalyzes reaction with H 2 O </li></ul></ul><ul><ul><li>produces carbonic acid (H 2 CO 3 ) </li></ul></ul><ul><li>Carbonic acid (H 2 CO 3 ): </li></ul><ul><ul><li>dissociates into hydrogen ion (H + ) and bicarbonate ion (HCO 3 — ) </li></ul></ul><ul><li>Hydrogen ions diffuse out of RBC, lowering pH </li></ul>
  • 120. 2,3-biphosphoglycerate (BPG) <ul><li>RBCs generate ATP by glycolysis: </li></ul><ul><ul><li>forming lactic acid and BPG </li></ul></ul><ul><li>BPG directly affects O 2 binding and release: </li></ul><ul><ul><li>more BPG, more oxygen released </li></ul></ul><ul><li>BPG levels rise: </li></ul><ul><ul><li>when pH increases </li></ul></ul><ul><ul><li>when stimulated by certain hormones </li></ul></ul><ul><li>If BPG levels are too low: </li></ul><ul><ul><li>hemoglobin will not release oxygen </li></ul></ul>
  • 121. Fetal and Adult Hemoglobin Figure 23–22
  • 122. Fetal and Adult Hemoglobin <ul><li>The structure of fetal hemoglobin : </li></ul><ul><ul><li>differs from that of adult Hb </li></ul></ul><ul><li>At the same P O 2 : </li></ul><ul><ul><li>fetal Hb binds more O 2 than adult Hb </li></ul></ul><ul><ul><li>which allows fetus to take O 2 from maternal blood </li></ul></ul>
  • 123. KEY CONCEPT <ul><li>Hemoglobin in RBCs: </li></ul><ul><ul><li>carries most blood oxygen </li></ul></ul><ul><ul><li>releases it in response to low O 2 partial pressure in surrounding plasma </li></ul></ul><ul><li>If P O 2 increases, hemoglobin binds oxygen </li></ul><ul><li>If P O 2 decreases, hemoglobin releases oxygen </li></ul><ul><li>At a given P O 2 : </li></ul><ul><ul><li>hemoglobin will release additional oxygen </li></ul></ul><ul><ul><li>if pH decreases or temperature increases </li></ul></ul>
  • 124. How is carbon dioxide transported in the blood? Carbon Dioxide Transport Figure 23–23 (Navigator) Respiration: Carbon Dioxide and Oxygen Exchange PLAY InterActive Physiology: Respiratory System: Gas Transport PLAY
  • 125. Carbon Dioxide (CO 2 ) <ul><li>Is generated as a byproduct of aerobic metabolism (cellular respiration) </li></ul><ul><li>CO 2 in the Blood Stream </li></ul><ul><li>May be: </li></ul><ul><ul><li>converted to carbonic acid </li></ul></ul><ul><ul><li>bound to protein portion of hemoglobin </li></ul></ul><ul><ul><li>dissolved in plasma </li></ul></ul><ul><ul><li>Bicarbonate Ions </li></ul></ul><ul><li>Move into plasma by an exchange mechanism (the chloride shift ) that takes in Cl — ions without using ATP </li></ul>
  • 126. CO 2 in the Blood Stream <ul><li>70% is transported as carbonic acid (H 2 CO 3 ): </li></ul><ul><ul><li>which dissociates into H + and bicarbonate (HCO 3 — ) </li></ul></ul><ul><li>23% is bound to amino groups of globular proteins in Hb molecule: </li></ul><ul><ul><li>forming carbaminohemoglobin </li></ul></ul><ul><li>7% is transported as CO 2 dissolved in plasma </li></ul>
  • 127. KEY CONCEPT <ul><li>CO 2 travels in the bloodstream primarily as bicarbonate ions, which form through dissociation of carbonic acid produced by carbonic anhydrase in RBCs </li></ul><ul><li>Lesser amounts of CO 2 are bound to Hb or dissolved in plasma </li></ul>
  • 128. Summary: Gas Transport Figure 23–24
  • 129. Control of Respiration <ul><li>Gas diffusion at peripheral and alveolar capillaries maintain balance by: </li></ul><ul><ul><li>changes in blood flow and oxygen delivery </li></ul></ul><ul><ul><li>changes in depth and rate of respiration </li></ul></ul>InterActive Physiology: Respiratory System: Control of Respiration PLAY
  • 130. Local Regulation of O 2 Transport (1 of 2) <ul><li>O 2 delivery in tissues and pickup at lungs are regulated by: </li></ul><ul><ul><li>rising P CO 2 levels: </li></ul></ul><ul><ul><ul><li>relaxes smooth muscle in arterioles and capillaries </li></ul></ul></ul><ul><ul><ul><li>increases blood flow </li></ul></ul></ul><ul><ul><li>coordination of lung perfusion and alveolar ventilation: </li></ul></ul><ul><ul><ul><li>shifting blood flow </li></ul></ul></ul><ul><ul><li>P CO 2 levels: </li></ul></ul><ul><ul><ul><li>control bronchoconstriction and bronchodilation </li></ul></ul></ul>
  • 131. Respiratory Centers of the Brain <ul><li>When oxygen demand rises: </li></ul><ul><ul><li>cardiac output and respiratory rates increase under neural control </li></ul></ul><ul><li>Have both voluntary and involuntary components </li></ul><ul><li>Involuntary Centers </li></ul><ul><li>Regulate respiratory muscles </li></ul><ul><li>In response to sensory information </li></ul>
  • 132. Voluntary Centers <ul><li>In cerebral cortex affect: </li></ul><ul><ul><li>respiratory centers of pons and medulla oblongata </li></ul></ul><ul><ul><li>motor neurons that control respiratory muscles </li></ul></ul><ul><ul><li>The Respiratory Centers </li></ul></ul><ul><li>3 pairs of nuclei in the reticular formation of medulla oblongata and pons </li></ul>
  • 133. Respiratory Rhythmicity Centers of the Medulla Oblongata <ul><li>Set the pace of respiration </li></ul><ul><li>Can be divided into 2 groups: </li></ul><ul><ul><li>Dorsal respiratory group (DRG)- </li></ul></ul><ul><li>Inspiratory center </li></ul><ul><li>Functions in quiet and forced breathing </li></ul><ul><li>Inspiratory and expiratory center </li></ul><ul><li>Functions only in forced breathing </li></ul><ul><li>Ventral respiratory group (VRG) </li></ul>
  • 134. Quiet Breathing Figure 23–25a <ul><li>Brief activity in the DRG: </li></ul><ul><ul><li>stimulates inspiratory muscles </li></ul></ul><ul><li>DRG neurons become inactive: </li></ul><ul><ul><li>allowing passive exhalation </li></ul></ul>
  • 135. Forced Breathing Figure 23–25b <ul><li>Increased activity in DRG: </li></ul><ul><ul><li>stimulates VRG </li></ul></ul><ul><ul><li>which activates accessory inspiratory muscles </li></ul></ul><ul><li>After inhalation: </li></ul><ul><ul><li>expiratory center neurons stimulate active exhalation </li></ul></ul>
  • 136. The Apneustic and Pneumotaxic Centers of the Pons <ul><li>Paired nuclei that adjust output of respiratory rhythmicity centers: </li></ul><ul><ul><li>regulating respiratory rate and depth of respiration </li></ul></ul><ul><ul><li>An Apneustic Center </li></ul></ul><ul><li>Provides continuous stimulation to its DRG center </li></ul><ul><li>Pneumotaxic Centers </li></ul><ul><li>Inhibit the apneustic centers </li></ul><ul><li>Promote passive or active exhalation </li></ul>
  • 137. Respiratory Centers and Reflex Controls Figure 23–26 <ul><li>Interactions between VRG and DRG: </li></ul><ul><ul><li>establish basic pace and depth of respiration </li></ul></ul><ul><li>The pneumotaxic center: </li></ul><ul><ul><li>modifies the pace </li></ul></ul>
  • 138. SIDS <ul><li>Also known as sudden infant death syndrome </li></ul><ul><li>Disrupts normal respiratory reflex pattern </li></ul><ul><li>May result from connection problems between pacemaker complex and respiratory centers </li></ul><ul><li>Respiratory Reflexes- Changes in patterns of respiration induced by sensory input </li></ul>
  • 139. 5 Sensory Modifiers of Respiratory Center Activities <ul><li>Chemoreceptors are sensitive to: </li></ul><ul><ul><li>P CO 2 , P O 2 , or pH </li></ul></ul><ul><ul><li>of blood or cerebrospinal fluid </li></ul></ul><ul><li>Baroreceptors in aortic or carotic sinuses: </li></ul><ul><ul><li>sensitive to changes in blood pressure </li></ul></ul>
  • 140. 5 Sensory Modifiers of Respiratory Center Activities <ul><li>Stretch receptors: </li></ul><ul><ul><li>respond to changes in lung volume </li></ul></ul><ul><li>Irritating physical or chemical stimuli: </li></ul><ul><ul><li>in nasal cavity, larynx, or bronchial tree </li></ul></ul><ul><li>Other sensations including: </li></ul><ul><ul><li>pain </li></ul></ul><ul><ul><li>changes in body temperature </li></ul></ul><ul><ul><li>abnormal visceral sensations </li></ul></ul>
  • 141. Chemoreceptor Reflexes <ul><li>Respiratory centers are strongly influenced by chemoreceptor input from: </li></ul><ul><ul><li>* cranial nerve IX - The glossopharyngeal nerve: </li></ul></ul><ul><ul><li>from carotid bodies </li></ul></ul><ul><ul><li>stimulated by changes in blood pH or P O 2 </li></ul></ul><ul><ul><li>* cranial nerve X -The vagus nerve: </li></ul></ul><ul><ul><li>from aortic bodies </li></ul></ul><ul><ul><li>stimulated by changes in blood pH or P O 2 </li></ul></ul><ul><ul><li>* receptors that monitor cerebrospinal fluid- </li></ul></ul><ul><li>Are on ventrolateral surface of medulla oblongata </li></ul><ul><li>Respond to P CO 2 and pH of CSF </li></ul>
  • 142. Chemoreceptor Responses to PCO 2 Figure 23–27
  • 143. <ul><li>Hypercapnia - An increase in arterial P CO 2 </li></ul><ul><li>Stimulates chemoreceptors in the medulla oblongata: </li></ul><ul><ul><li>to restore homeostasis </li></ul></ul><ul><ul><li>Hypoventilation- A common cause of hypercapnia </li></ul></ul><ul><li>Abnormally low respiration rate: </li></ul><ul><ul><li>allows CO 2 build-up in blood </li></ul></ul><ul><ul><li>Hyperventilation- Excessive ventilation </li></ul></ul><ul><li>Results in abnormally low P CO 2 ( hypocapnia ) </li></ul><ul><li>Stimulates chemoreceptors to decrease respiratory rate </li></ul>
  • 144. Baroreceptor Reflexes <ul><li>Carotid and aortic baroreceptor stimulation: </li></ul><ul><ul><li>affects blood pressure and respiratory centers </li></ul></ul><ul><li>When blood pressure falls: </li></ul><ul><ul><li>respiration increases </li></ul></ul><ul><li>When blood pressure increases: </li></ul><ul><ul><li>respiration decreases </li></ul></ul>
  • 145. Protective Reflexes <ul><li>Triggered by receptors in epithelium of respiratory tract when lungs are exposed to: </li></ul><ul><ul><li>toxic vapors </li></ul></ul><ul><ul><li>chemicals irritants </li></ul></ul><ul><ul><li>mechanical stimulation </li></ul></ul><ul><li>Cause sneezing, coughing, and laryngeal spasm </li></ul>
  • 146. Apnea <ul><li>A period of suspended respiration </li></ul><ul><li>Normally followed by explosive exhalation to clear airways: </li></ul><ul><ul><li>sneezing and coughing </li></ul></ul><ul><ul><li>Laryngeal Spasm </li></ul></ul><ul><li>Temporarily closes airway: </li></ul><ul><ul><li>to prevent foreign substances from entering </li></ul></ul>
  • 147. The Cerebral Cortex and Respiratory Centers <ul><li>Strong emotions: </li></ul><ul><ul><li>can stimulate respiratory centers in hypothalamus </li></ul></ul><ul><li>2. Temporarily closes airway: </li></ul><ul><ul><li>to prevent foreign substances from entering </li></ul></ul><ul><li>Anticipation of strenuous exercise: </li></ul><ul><ul><li>can increase respiratory rate and cardiac output </li></ul></ul><ul><ul><li>by sympathetic stimulation </li></ul></ul>
  • 148. KEY CONCEPTS <ul><li>A basic pace of respiration is established between respiratory centers in the pons and medulla oblongata, and modified in response to input from: </li></ul><ul><ul><li>Chemoreceptors, baroreceptors, stretch receptors </li></ul></ul><ul><li>In general, CO 2 levels, rather than O 2 levels, are primary drivers of respiratory activity </li></ul><ul><li>Respiratory activity can be interrupted by protective reflexes and adjusted by the conscious control of respiratory muscles </li></ul>
  • 149. Changes in Respiratory System at Birth (1) <ul><li>Before birth: </li></ul><ul><ul><li>pulmonary vessels are collapsed </li></ul></ul><ul><ul><li>lungs contain no air </li></ul></ul><ul><li>During delivery: </li></ul><ul><ul><li>placental connection is lost </li></ul></ul><ul><ul><li>blood P O 2 falls </li></ul></ul><ul><ul><li>P CO 2 rises </li></ul></ul><ul><li>At birth: </li></ul><ul><ul><li>newborn overcomes force of surface tension to inflate bronchial tree and alveoli and take first breath </li></ul></ul>
  • 150. Changes in Respiratory System at Birth (2) <ul><li>Large drop in pressure at first breath: </li></ul><ul><ul><li>pulls blood into pulmonary circulation </li></ul></ul><ul><ul><li>closing foramen ovale and ductus arteriosus </li></ul></ul><ul><ul><li>redirecting fetal blood circulation patterns </li></ul></ul><ul><li>Subsequent breaths: </li></ul><ul><ul><li>fully inflate alveoli </li></ul></ul>
  • 151. Respiratory Performance and Age Figure 23–28
  • 152. 3 Effects of Aging on the Respiratory System <ul><li>Elastic tissues deteriorate: </li></ul><ul><ul><li>reducing lung compliance </li></ul></ul><ul><ul><li>lowering vital capacity </li></ul></ul><ul><li>Arthritic changes: </li></ul><ul><ul><li>restrict chest movements </li></ul></ul><ul><ul><li>limit respiratory minute volume </li></ul></ul><ul><li>Emphysema: </li></ul><ul><ul><li>affects individuals over age 50 </li></ul></ul><ul><ul><li>depending on exposure to respiratory irritants ( e.g., cigarette smoke) </li></ul></ul>
  • 153. Integration with Other Systems <ul><li>Maintaining homeostatic O 2 and CO 2 levels in peripheral tissues requires coordination between several systems: </li></ul><ul><ul><li>particularly the respiratory and cardiovascular systems </li></ul></ul>
  • 154. Coordination of Respiratory and Cardiovascular Systems <ul><li>Improves efficiency of gas exchange: </li></ul><ul><ul><li>by controlling lung perfusion </li></ul></ul><ul><li>Increases respiratory drive: </li></ul><ul><ul><li>through chemoreceptor stimulation </li></ul></ul><ul><li>Raises cardiac output and blood flow: </li></ul><ul><ul><li>through baroreceptor stimulation </li></ul></ul>
  • 155. The Respiratory System and Other Systems Figure 23–29
  • 156. SUMMARY (1 of 4) <ul><li>5 functions of the respiratory system: </li></ul><ul><ul><li>gas exchange between air and circulating blood </li></ul></ul><ul><ul><li>moving air to and from exchange surfaces </li></ul></ul><ul><ul><li>protection of respiratory surfaces </li></ul></ul><ul><ul><li>sound production </li></ul></ul><ul><ul><li>facilitating olfaction </li></ul></ul><ul><li>Structures and functions of the respiratory tract: </li></ul><ul><ul><li>alveoli </li></ul></ul><ul><ul><li>respiratory mucosa </li></ul></ul><ul><ul><li>lamina propria </li></ul></ul><ul><ul><li>respiratory defense system </li></ul></ul>
  • 157. SUMMARY (2 of 4) <ul><li>Structures and functions of the upper respiratory system: </li></ul><ul><ul><li>the nose and nasal cavity </li></ul></ul><ul><ul><li>the pharynx </li></ul></ul><ul><li>Structures and functions of the larynx: </li></ul><ul><ul><li>cartilages and ligaments </li></ul></ul><ul><ul><li>sound production </li></ul></ul><ul><ul><li>the laryngeal musculature </li></ul></ul><ul><li>Structures and functions of the trachea and primary bronchi </li></ul>
  • 158. SUMMARY (3 of 4) <ul><li>Structures and functions of the lungs: </li></ul><ul><ul><li>lobes and surfaces, the bronchi </li></ul></ul><ul><ul><li>the bronchioles, alveoli and alveolar ducts </li></ul></ul><ul><ul><li>blood supply to the lungs </li></ul></ul><ul><ul><li>pleural cavities and membranes </li></ul></ul><ul><li>Respiratory physiology: </li></ul><ul><ul><li>external respiration </li></ul></ul><ul><ul><li>internal respiration </li></ul></ul><ul><li>Pulmonary ventilation: </li></ul><ul><ul><li>air movement </li></ul></ul><ul><ul><li>pressure changes </li></ul></ul><ul><ul><li>the mechanics of breathing </li></ul></ul><ul><ul><li>respiratory rates and volumes </li></ul></ul>
  • 159. SUMMARY (4 of 4) <ul><li>Gas exchange: </li></ul><ul><ul><li>the gas laws </li></ul></ul><ul><ul><li>diffusion and respiration </li></ul></ul><ul><li>Gas pickup and delivery: </li></ul><ul><ul><li>partial pressure </li></ul></ul><ul><ul><li>oxygen transport (RBCs and hemoglobin) </li></ul></ul><ul><ul><li>carbon dioxide transport </li></ul></ul><ul><li>Control of respiration: </li></ul><ul><ul><li>local regulation (lung perfusion, alveolar ventilation) </li></ul></ul><ul><ul><li>respiratory centers of the brain </li></ul></ul><ul><ul><li>respiratory reflexes </li></ul></ul><ul><ul><li>voluntary control of respiration </li></ul></ul><ul><li>Changes in the respiratory system at birth </li></ul><ul><li>Aging and the respiratory system </li></ul>

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