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Chapter 17

Chapter 17. Mechanics of Breathing. About this Chapter. The respiratory system Gas laws Ventilation. Respiratory System. Functions External Respiration Exchange of gases between the atmosphere and the blood Homeostatic regulation of body pH

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Chapter 17

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  1. Chapter 17 Mechanics of Breathing

  2. About this Chapter • The respiratory system • Gas laws • Ventilation

  3. Respiratory System Functions • External Respiration • Exchange of gases between the atmosphere and the blood • Homeostatic regulation of body pH • Protection from inhaled pathogens and irritating substances • Vocalization

  4. Respiratory System Principles of Bulk Flow • Flow from regions of higher to lower pressure • Muscular pump creates pressure gradients • Resistance to flow • Diameter of tubes

  5. CO2 O2 Exchange I:atmosphereto lung(ventilation) Airways Alveoliof lungs O2 CO2 Exchange II:lung to blood O2 CO2 Pulmonarycirculation Transport ofgases inthe blood Systemiccirculation O2 CO2 CO2 Exchange III:blood to cells O2 Cellularrespiration Cells Nutrients ATP Respiratory System • Overview of external and cellular respiration Figure 17-1

  6. Respiratory System Components • Conducting system • Alveoli • Bones and muscle of thorax

  7. Respiratory System ANATOMY SUMMARY THE LUNGS AND THORACIC CAVITY Pharynx Nasal cavity Vocal cords Upperrespiratorysystem Tongue Esophagus Larynx Trachea Lowerrespiratorysystem Right lung Left lung Diaphragm Left bronchus Rightbronchus (a) The respiratory system Figure 17-2a

  8. Muscles Used for Ventilation Sternocleido-mastoids Scalenes Internalintercostals Externalintercostals Diaphragm Abdominalmuscles Muscles ofinspiration Muscles ofexpiration (b) Muscles used for ventilation Figure 17-2b

  9. The Respiratory System Air spaceof lung Air-filledballoon Pleuralfluid Pleuralmembrane Fluid-filled balloon Figure 17-3

  10. Branching of Airways ANATOMY SUMMARY THE LUNGS AND THORACIC CAVITY Larynx Trachea Cartilagering Left primarybronchus Secondarybronchus Bronchiole Alveoli (e) Branching of airways Figure 17-2e

  11. Branching of the Airways Figure 17-4

  12. Conditioning Air • Warming air to body temperature • Adding water vapor • Filtering out foreign material

  13. Ciliated Respiratory Epithelium Cilia move mucus to pharynx Dust particle Mucus layer trapsinhaled particles. inhaled particles. Watery saline layerallows cilia topush mucustoward pharynx. Cilia Goblet cellsecretes mucus. Nucleus ofcolumnarepithelial cell Basementmembrane Ciliated epithelium of the trachea Figure 17-5

  14. Alveolar Structure – Note cell types of alveoli Figure 17-2g

  15. Pulmonary Circulation • Right ventricle  pulmonary trunk  lungs  pulmonary veins  left atrium • Note oxygenation

  16. Anatomy Review PLAY Interactive Physiology® Animation: Respiratory System: Anatomy Review

  17. Gas Laws Table 17-1

  18. Gas Laws • Pgas = Patm % of gas in atmosphere Table 17-2

  19. Boyle’s Law • Gases move from areas of high pressure to areas of low pressure Figure 17-6

  20. Spirometer Bell Inspiration Expiration Inspiration Expiration Air 0.5 Volume(L) Water 0 Time Figure 17-7

  21. Lung Volumes and Capacities Figure 17-8

  22. Air Flow • Flow  P/R • Alveolar pressure or intrapleural pressure can be measured • Single respiratory cycle consists of one inspiration followed by one expiration

  23. Movement of the Diaphragm Figure 17-9a

  24. Movement of the Diaphragm Figure 17-9b

  25. Movement of the Diaphragm Figure 17-9c

  26. Dimensions of the Thoracic Cavity During Inspiration Figure 17-10a

  27. Dimensions of the Thoracic Cavity During Inspiration Figure 17-10b

  28. Pressure Changes During Quiet Breathing Inspiration Expiration Inspiration Expiration +2 Alveolarpressure(mm Hg) A4 Trachea +1 A1 0 A3 A5 Bronchi –1 A2 –2 Lung Intrapleuralpressure(mm Hg) B3 B1 –3 –4 –5 Diaphragm –6 B2 Right pleuralcavity Left pleuralcavity 750 Volumeof airmoved(mL) 500 C2 250 C3 C1 0 1 2 3 4 5 6 7 8 Time (sec) Figure 17-11

  29. Subatmospheric Pressure in the Pleural Cavity P = –3 mm HgIntrapleural pressureis subatmospheric. Ribs Intrapleuralspace Pleuralmembranes Diaphragm Elastic recoil of thechest wall tries to pullthe chest wall outward. Elastic recoil of lungcreates an inward pull. (a) Normal lung at rest Figure 17-12a

  30. Subatmospheric Pressure in the Pleural Cavity • Pneumothorax results in collapsed lung that cannot function normally P = Patm Knife Lung collapses tounstretched size Air Intrapleuralspace Pleuralmembranes The rib cageexpands slightly. If the sealed pleural cavity is openedto the atmosphere, air flows in. (b) Pneumothorax Figure 17-12b

  31. Compliance and Elastance • Compliance: ability to stretch • High compliance • Stretches easily • Low compliance • Requires more force • Restrictive lung diseases • Fibrotic lung diseases • Inadequate surfactant production • Elastance: returning to its resting volume when stretching force is released

  32. Law of LaPlace • Surface tension is created by the thin fluid layer between alveolar cells and the air Figure 17-13

  33. Surfactant • More concentrated in smaller alveoli • Mixture containing proteins and phospholipids • Newborn respiratory distress syndrome • Premature babies • Inadequate surfactant concentrations

  34. Air Flow Table 17-3

  35. Pulmonary Ventilation PLAY Interactive Physiology® Animation: Respiratory System: Pulmonary Ventilation

  36. Ventilation • Total pulmonary ventilation is greater than alveolar ventilation because of dead space • Total pulmonary ventilation = ventilation rate  tidal volume

  37. P = O2 ~ P ~ O2 Ventilation Dead space filledwith fresh air The first exhaledair comes out ofthe dead space.Only 350 mLleaves the alveoli. 150mL 1 End of inspiration 1 2700 mL 2 Exhale 500 mL(tidal volume) Atmospheric air 150 350 At the end of expiration, thedead space is filled with“stale” air from alveoli. 3 2 Dead space isfilled withfresh air. 150mL 150 RESPIRATORYCYCLE INADULT 4 Inhale 500 mLof fresh air (tidal volume). Only 350 mLof fresh airreaches alveoli 350 2200 mL 150 2200 mL The first 150 mLof air into thealveoli is staleair from thedead space. 4 Dead space filledwith stale air KEY 150 mm Hg (fresh air) 150mL 100 mm Hg (stale air) 3 2200 mL Figure 17-14

  38. Ventilation • Alveolar ventilation = ventilation rate  (tidal volume – dead space volume) Table 17-4

  39. Ventilation Table 17-5

  40. Ventilation Table 17-6

  41. Ventilation • As alveolar ventilation increases, alveolar PO2 increases and PCO2 decreases Figure 17-15

  42. Ventilation Table 17-7

  43. Ventilation • Local control mechanisms attempt to match ventilation and perfusion Figure 17-16a

  44. Ventilation Figure 17-16b

  45. Ventilation Figure 17-16c

  46. Ventilation • Auscultation = diagnostic technique • Obstructive lung diseases • Asthma • Emphysema • Chronic bronchitis

  47. Summary • Respiratory system • Cellular respiration, external respiration, respiratory system, upper respiratory tract, pharynx, and larynx • Lower respiratory tract, trachea, bronchi, bronchioles, alveoli, Type I and Type II alveolar cells • Diaphragm, intercostal muscles, lung, pleural sac, and pleural fluid • Gas Laws: Dalton’s law and Boyle’s law

  48. Summary • Ventilation • Tidal volume, vital capacity, residual volume, and respiratory cycle • Alveolar pressure, active expiration, intrapleural pressures, compliance, elastance, surfactant, bronchoconstriction, and bronchodilation • Total pulmonary ventilation, alveolar ventilation, hyperventilation, and hypoventilation

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