2. RESPIRATORY SYSTEM Chapter 19 19-1

3. Functions of the Respiratory System Supply oxygen from the air to body cells and transport carbon dioxide from the body to the air Speech Acid base balance Body defenses against infection Hormonal regulation of blood pressure

4. Processes of Respiration breathing or ventilation external respiration transport internal respiration cellular respiration Respiration is the process of exchanging gases between the atmosphere and body cells. Consists of the following events: 19-2

5. Why We Breathe

6. Organs of the Respiratory System 19-3

7. Upper Respiratory Tract 19-4

8. Mucous in Respiratory Tract Cilia move mucus and trapped particles from the nasal cavity to the pharynx 19-5

9. Sinuses Air-filled spaces in maxillary, frontal, ethmoid, and sphenoid bones 19-6

10. Pharynx Nasopharynx Oropharynx Laryngopharynx

11. Larynx 19-7

12. Vocal Cords 19-8

13. Vocal Cords

14. Trachea

15. Cross section of trachea Wall of trachea 19-9

16. Tracheostomy Performed to allow air to bypass an obstruction within the larynx 19-10

17. Bronchial Tree

18. Primary bronchi-lung Secondary bronchi-lobe Tertiary bronchi-bronchopulmonary unit Intralobular bronchioles-lobules Terminal bronchioles Respiratory bronchioles Alveolar duct Alveolar sacs Alveoli

19. Bronchial Tree 19-11

20. Bronchial Tree 19-12

21. Bronchial Tree Structural changes that occur as the tubes become smaller Cartilage Smooth Muscle Epithelial Lining

22. Alveoli

23. Lungs

24. Transverse Section of Lungs 19-15

25. Breathing Mechanism Boyle’s Law Pressure of a gas in a closed container is inversely proportional to the volume of the container Volume increases Pressure decreases Gases flow from high to low pressure Gas pressure is measured relative to atmospheric pressure-760mmHg

26. Lungs at Rest When lungs are at rest, the pressure on the inside of the lungs is equal to the pressure on the outside of the thorax 19-16

27. Air Movements Moving the plunger of a syringe causes air to move in or out Air movements in and out of the lungs occur in much the same way 19-17

28. Animation: Alveolar Pressure Changes During Inspiration and Expiration

29. Inspiration Intra-alveolar pressure decreases to about 758mm Hg as the thoracic cavity enlarges Atmospheric pressure forces air into the airways 19-18

30. Surfactant Prevents Alveoli From Collapsing During Breathing

31. Maximal Inspiration Thorax at end of normal inspiration Thorax at end of maximal inspiration aided by contraction of sternocleidomastoid and pectoralis minor muscles 19-19

32. Expiration due to elastic recoil of the lung tissues and abdominal organs 19-20

33. Maximal Expiration contraction of abdominal wall muscles contraction of posterior internal intercostal muscles 19-21

34. Terms Compliance-ease with which the lungs can be inflated Pneumothorax-air in the chest

35. Respiratory Volumes tidal volume – volume moved in or out during a normal breath, 500 ml inspiratory reserve volume – volume that can be inhaled during forced breathing in addition to tidal volume, 3,000ml expiratory reserve volume – volume that can be exhaled during forced breathing in addition to tidal volume, 1,100ml residual volume – volume that remains in lungs at all times, 1,200ml 19-22

36. Respiratory Capacities inspiratory capacity = tidal volume + inspiratory reserve volume functional residual capacity = expiratory reserve volume + the residual volume vital capacity = tidal volume + inspiratory reserve volume + expiratory reserve volume Maximum amount of air that can be exhaled after a maximum inspiration total lung capacity = vital capacity + residual volume 19-23

37. Respiratory Volumes and Capacities 19-24

38. Non-Useful Air Anatomic dead space-air filling the conducting airway passages that does not participate in gas exchange, 150ml Alveolar dead space-non functioning parts of the lungs, usually 0 in a healthy individual Physiologic dead space-anatomic plus alveolar dead space

39. Alveolar Ventilation alveolar ventilation rate major factor affecting concentrations of oxygen and carbon dioxide in the alveoli tidal volume minus physiologic dead space then multiplied by breathing rate (500ml - 150ml) x 12 breaths per min = 4,200 ml/min 19-25

40. Nonrespiratory Air Movements coughing sneezing laughing crying hiccuping yawning speech 19-26

41. Control of Breathing Nervous Control Two separate mechanisms Voluntary system –originates in the cerebral cortex and controls breathing during speaking and eating Involuntary system –located in the medulla oblongata and pons, –called the respiratory center –regulates respiration according to the metabolic needs of the body

42. 41 Respiratory Areas Groups of neurons in the brainstem comprise the respiratory areas that control breathing Impulses travel on cranial nerves and spinal nerves, causing inspiration and expiration Respiratory areas also adjust the rate and depth of breathing The respiratory areas include: Medullary respiratory center Ventral and dorsal respiratory groups Pontine respiratory group Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Diaphragm Medulla oblongata Pons Midbrain Dorsal respiratory group Pontine respiratory group Ventral respiratory group Fourth ventricle Medullary respiratory center Internal (expiratory) intercostal muscles External (inspiratory) intercostal muscles

43. 42 Dorsal respiratory group Ventral respiratory group Respiratory muscles Changes in breathing Basic rhythm of breathing Respiratory areas Pontine respiratory group Medullary respiratory center Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

44. Control of Breathing- Chemical Control CO 2 + H 2 O  H 2 CO 3  H + + HCO3 - high blood P CO 2 and high cerebral spinal fluid H + concentrations stimulate chemoreceptors of the respiratory center alveolar ventilation increases CO 2 levels decrease in blood H + decrease in cerebrospinal fluid 19-31

45. Factors Affecting Breathing- Chemicals Decreased blood oxygen concentration stimulates peripheral chemoreceptors in the carotid and aortic bodies Does not occur until O 2 concentration is low 19-29

46. Factors Affecting Breathing- Respiratory Reflexes Hering Breur Reflex expansion of lungs stimulates stretch receptors in the lungs inhibitory impulses from receptors to respiratory center prevent overinflation of lungs 19-30

47. Alveolar Gas Exchange- Structure of Alveoli allow air to pass from one alveolus to another 19-32

48. Respiratory Membrane consists of the walls of the alveolus and the capillary 19-33

49. Respiratory Membrane Surfactant layer Simple squamous epithelium of the alveolar wall Basement membrane of the alveolar wall Interstitial space with connective tissue and tissue fluid Capillary basement membrane Capillary endothelium

50. 49 Animation: Movement of Oxygen and Carbon Dioxide

51. Diffusion Through the Respiratory Membrane-Partial Pressures Composition of atmospheric air –21% oxygen –79% nitrogen –.04% carbon dioxide Dalton’s Law –In a mixture of gases, each of the gases exerts its own pressure in proportion to its % in the mixture –Partial pressure is designated with the symbol “P” in front of the chemical symbol for the gas –Partial pressure is expressed in mmHg

52. Partial Pressures Examples PO 2 in the atmosphere= 21/100 x 760mmHg = 160mmHg PCO 2 in atmosphere=.04/100 x 760 mmHg =.3mmHg

53. Diffusion Through Respiratory Membrane Gases are exchanged between alveolar air and capillary blood because of differences in partial pressure Gases diffuse from high to low partial pressure, regardless of what other gases are present 19-34

54. 53 Animation: Gas Exchange During Respiration

55. Oxygen Transport-Hemoglobin Hb + O 2  HbO 2 Hemoglobin is an allosteric protein with 4 binding sites for oxygen

56. Oxygen Transport Most oxygen binds to hemoglobin to form oxyhemoglobin Oxyhemoglobin releases oxygen in the regions of body cells 19-35

57. Oxygen Release Amount of oxygen released from oxyhemoglobin increases as partial pressure of carbon dioxide increases the blood pH decreases blood temperature increases 19-36

58. Carbon Dioxide Transport dissolved in plasma combined with hemoglobin in the form of bicarbonate ions 19-37

59. Chloride Shift bicarbonate ions diffuse out erythrocytes chloride ions from plasma diffuse into erythrocytes electrical balance is maintained 19-38

60. Carbon Dioxide in Lungs 19-39

61. Disorders Pneumonia –Aveoli fill with fluid and pus –Virus or bacteria Emphysema –Progressive, degenerative disease –Alveolar walls break down Tuberculosis –Bacteria –Fibrous connective tissue forms around sites of infection forming structures called tubercles Asthma –Usually allergic reaction –Wall of bronchioles become edemas and cells secrete large amount of mucus – muscles in bronchioles contract

62. Disorders Pleurisy –Inflammation of pleural membranes Rhinitis –Inflammation of nasal cavity lining Sinusitis –Mucus membrane of the sinuses become inflamed Bronchitis –Inflammation of the bronchial lining

63. Disorders Carbon Monoxide Poisoning –Carbon monoxide competes for the active site filled by oxygen on hemoglobin –Does not dissociate Sleep Apnea –Stop breathing during sleep –Results in headache, fatigue, depression and drowsiness Respiratory Distress Syndrome –No surfactant –Alveoli collapse –Usually occurs in premature infants Sudden Infant Death Syndrome –Cause unknown –Death in children under one year of age –May be due to immaturity of respiratory center

64. Disorders Laryngitis –Inflammation of the vocal cords or laryngeal tissue Stuttering –Vocal cords are out of control Lung Cancer

65. Clinical Application The Effects of Cigarette Smoking on the Respiratory System cilia disappear excess mucus produced lung congestion increases lung infections lining of bronchioles thicken bronchioles lose elasticity emphysema fifteen times more common lung cancer more common much damage repaired when smoking stops 19-41

66. Life-Span Changes reflect accumulation of environmental influences reflect the effects of aging in other organ systems cilia less active mucous thickens swallowing, gagging, and coughing reflexes slow macrophages in lungs lose efficiency increased susceptibility to respiratory infections “barrel chest” may develop bronchial walls thin and collapse dead space increases 19-40