The Respiratory System

1. The Respiratory System

2. Respiratory System Functions • Pulmonary ventilation movement of air into and out of lungs “breathing” • External respiration movement of O2 and CO2 between blood and lungs • Transport of respiratory gases transport of O2 and CO2 between tissue and lungs • Internal respiration movement of O2 and CO2 between blood and tissue • Olfaction

3. Respiratory System • Upper respiratory system • Lower respiratory system • Conducting Zone • Respiratory Zone • Respiratory mucosa • Respiratory defense system (adaptive or innate?)

4. Upper Respiratory • External nares • Nasal cavity • Warm, moisten & filter air (Nasal conchae, surface area) • Detect smell (olfactory epithelium) • Modifying sounds by resonance • Pharynx both respiratory & digestive pathway

5. Larynx • Provide an open airway • to route air and food properly • Produce a voice

6. Sound Production • Phonation • Articulation

7. Trachea • “windpipe” • Lined in mucosa with cilia that propel debris laden mucus to the pharynx • (destroyed by smoking, use coughing instead)

8. Lungs

9. Lungs • Lobes • Superior, middle, inferior • Superior, inferior • Oblique fissures • Cardiac notch

10. Bronchial Tree • Primary bronchi • Secondary bronchi • Tertiary bronchi • Bronchopulmonarysegment • Bronchioles • Bronchodilation • Bronchoconstrction • Terminal bronchiole

11. Pulmonary lobule • Lymph vessel, arteriole, and venule • Respiratory bronchioles

12. Alveoli • Alveolar duct • Alveolar sacs • Alveoli • Capillaries • Elastic tissue

13. Alveoli • Type I alveolar cells • Alveolar macrophage • Type II alveolar cells (septal cells) • Surfactant • Surface tension • Respiratory distress syndrome (RDS)

14. Respiratory Physiology • Pulmonary ventilation “breathing” • Inhalation • Exhalation • External (pulmonary) respiration • Internal (tissue) respiration • Problems • Hypoxia • Ventilation-perfusion coupling • Anoxia

15. Respiratory Gas Laws

16. Boyle’s Law: P=1/V

17. Inhalation (inspiration) • Requires changes in air pressure. • At sea level air pressure is 1 atmosphere (atm) or 760mmHg. • During inhalation pressure must drop below 1 atm. • Gas particles move from an area of high pressure to an area of low pressure (diffusion). • Increasing the volume of a quantity of gas leads to a drop in pressure—an inverse relationship.

18. Respiration • Atmospheric pressure • Intrapulmonary pressure • Intrapleural pressure

19. Muscles of inspiration • Diaphragm • External intercostals • During forceful breathing • Sternocleidomastoid • Scalenes • Pectoralis minor

20. Muscles of expiration • Relaxation of inspiratory muscles • During forceful expiration • Internal intercostals • Abdominals

21. Respiratory Volumes • Tidal Volume each breath. • Inspiratory Capacity biggest inhale • Expiratory Reserve  biggest exhale • Vital Capacity maximum volume • Residual Volumeair left after exhale VD anatomical dead space

22. Respiratory Capacities • TLC • VC • IC • FRC

23. Spirogram of lung volumes

24. Inhalation and exhalation summary

25. Other factors affecting ventilation • Compliance • Elasticity • Surface tension • Thoracic mobility • Airway resistance • Airway diameter • Contraction and relaxation of smooth muscles • ANS input • Greatest resistance is in medium bronchi • Obstruction or collapse of airways

26. Gas exchange: Dalton’s Law • Dalton’s law—each gas exerts its own pressure • Atm=PN2+PO2+PH2O+PCO2+Pothergases • Inhaled air • PO2 = 159 mmHg • PCO2= 0.3 mmHg • Alveolar air • PO2 = 105 mmHg • PCO2= 40 mmHg • Exhaled air is a mixture of inhaled and alveolar air

27. Gas exchange: Henry’s Law • Henry’s law—the quantity of a gas that will dissolve in a liquid is proportional to the partial pressure of the gas AND the solubility each gas. • CO2 is 20X more soluble than O2

28. Gas Exchange • Partial pressure differences • Small distance • Molecular weight and solubility of gases • Large surface area • Coordinated blood- and airflow

29. Ventilation-perfusion coupling • Necessary for efficient gas exchange • Ventilationthe amount of gas reaching the alveoli • Perfusion blood flow in the capillaries

30. Oxygen transport • Red blood cells • Hb + O2« HbO2 • Hemoglobin saturation and affinity • PO2 of blood • Blood pH • PCO2 of blood • Temperature • Metabolism in RBC’s

31. Hemoglobin and PO2 • Oxygen-hemoglobin saturation curve • Shape of Hb changes as O2 binds • Cooperativity • Oxygen reserve • Oxygen “bars” • Carbon monoxide

32. Hemoglobin and pH • Normal blood—pH = 7.4 • Active tissues are acidic • Bohr Effect interaction between hemoglobin's affinity for oxygen and its affinity for hydrogen ions

33. Hemaglobin and PCO2 CO2 + H2O « H2CO3« H+ + HCO3-

34. Hemaglobin and Temperature • Normal blood has temperature = 37ºC • Active tissues havehigher temps

35. Hemaglobin and BPG • Biphosphoglycerate (BPG) found in RBCs decreases the affinity of Hb for O2 • Glycolysis produces lactic acid and BPG • BPG binds reversibly to Hb and is required for Hb to release O2

36. Fetal Hemoglobin • Higher affinity for O2 than adult Hb

37. CO2 Transport • Dissolved CO2 • Carbamino compounds • Carbaminohemoglobin • Bicarbonate ions • CO2 + H2O « H2CO3« H+ + HCO3- • Chloride shift • Haldane effect

38. Summary

39. Haldane effect • O2 effects on CO2 transport in blood

40. Nervous Control • Respiratory center • Medullary rhythmicity area • Ventral respiratory group responsible for pattern generation of breathing • Pontine respiratory group (Pneumotaxic area)

41. Chemical Control • PCO2 • PO2

43. Respiratory Reflexes • Chemoreceptors • Central • Peripheral • Aortic and carotid bodies • Hypercapnia • Involuntary hyperventilation • Hypocapnia • Voluntary hyperventilation

44. Homeostatic Imbalances • Rhinitis • Hyperventilation • Hyperapnea • COPD • Dyspnea • Emphysema • Bronchitis • Asthma • TB • Lung Cancer • Cystic Fibrosis

45. Resources • Interactive Respiratory Physiology • Function of the Respiratory System