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The Respiratory System

A. Organs 1. Nose a. Anatomy b. Physiology 2. Pharynx 3. Larynx 4. Trachea 5. Bronchi 6. Lungs a. Gross anatomy b. Lobes and fissures c. Lobules

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The Respiratory System

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  1. A. Organs 1. Nose a. Anatomy b. Physiology 2. Pharynx 3. Larynx 4. Trachea 5. Bronchi 6. Lungs a. Gross anatomy b. Lobes and fissures c. Lobules d. Alveolar-capillary (respiratory) membrane e. Blood supply to the lungs B. Physiology of respiration 1. Pulmonary ventilation a. Inspiration b. Expiration c. Compliance 2. Pulmonary air volumes and capacities a. Pulmonary volumes b. Pulmonary capacities 3. Exchange of oxygen and carbon dioxide a. Dalton's law 4. Physiology of external (pulmonary) respiration 5. Physiology of internal (tissue) respiration 6. Transport of oxygen and carbon dioxide a. Oxygen b. Carbon dioxide c. Summary of gas exchange in lungs and tissues C. Control of respiration 1. Nervous control a. Medullary rhythmicity area b. Pneumotaxic area c. Apneustic area 2. Regulation of respiratory center activity a. Cortical influences b. Inflation reflex c. Chemical regulation The Respiratory System

  2. Overview of Respiratory System

  3. The respiratory system has the following functions: • 1. gas exchange • 2. contains receptors for the sense of smell • 3. filters, warms, and moistens inspired air • 4. produces sounds • 5. helps eliminate wastes other than carbon dioxide

  4. Respiration is the exchange of gases between the atmosphere, the blood, and the body cells. • There are three basic processes involved: • 1. pulmonary ventilation • 2. external respiration • 3. internal respiration

  5. Respiratory Organs • 1. upper vs lower • 2. conducting vs respiratory

  6. Nose Anatomy • 1. external nose • 2. internal nose • 3. nasal cavity a. mucosa b. nasal septum c. vestibule d. nasal conchae (turbinate bones)

  7. Nose Physiology • 1. filter, moisten, and warm air • 2. olfaction • 3. resonating chamber

  8. Pharynx • 1. muscular tube • 2. location • 3. constrictor muscles • 4. divisions a. nasopharynx b. oropharynx c. laryngopharynx

  9. Larynx • 1. nine cartilages • 2. thyroid cartilage • 3. epiglottis • 4. cricoid cartilage • 5. laryngospasm • 6. mucosa • 7. vestibular folds • 8. vocal folds • 9. glottis • 10. voice production

  10. Larynx and Voice Production

  11. Trachea • 1. location • 2. mucosa • 3. submucosa • 4. cartilage • 5. adventitia

  12. Bronchial Tree • 1. primary bronchi • 2. secondary (lobar) bronchi ( 3 right, 2 left) • 3. tertiary (segmental) bronchi (10 right, 8 left) • 4. bronchioles • 5. terminal bronchioles • 6. respiratory bronchioles • 7. alveolar ducts and sacs • 8. alveoli

  13. Bronchial Tree Con’t • 1. primary bronchi • 2. secondary (lobar) bronchi • 3. tertiary (segmental) bronchi • 4. bronchioles • 5. terminal bronchioles • 6. respiratory bronchioles • 7. alveolar ducts and sacs • 8. alveoli

  14. Bronchial Tree (anatomical changes) • 1. cartilage Trachea – C-shaped cartilage Bronchi – irregular plates of cartilage Bronchioles – cartilage gone • 2. smooth muscle increases as cartilage decreases bronchodilation vs. bronchoconstriction • 3. epithelium ciliated pseudostratified + goblet cells (trachea) ciliated simple columnar + goblet cells ciliated simple cuboidal + goblet cells ciliated simple cuboidal simple cuboidal simple squamous (alveoli) alveolus Smooth muscle Simple cuboidal Lumen of bronchiole

  15. Lungs • 1. location • 2. pleurae a. parietal b. visceral • 3. pleural cavity (potential space) • 4. pleural fluid

  16. Pleura

  17. Lungs, con’t • 5. apex vs base • 6. hilus • 7. rt. lung = 3 lobes, 2 fissures (horizontal and oblique) • 8. lt. lung = 2 lobes, 1 fissure (oblique)

  18. Lungs, con’t • 9. bronchopulmonary segments • 10. lobules • 11. alveolus (3 cell types) a. squamous epithelial cell b. macrophage (dust cell) c. septal cell -- surfactant

  19. Alveolar-capillary membrane(respiratory membrane) • 1. surfactant • 2. alveolar epithelial cell • 3. fused basement membrane • 4. capillary endothelial cell

  20. Blood supply to the lungs • 1. pulmonary artery • 2. bronchial artery • 3. pulmonary veins

  21. Physiology of Respiration • What is the purpose of respiration? • What three processes are necessary to accomplish this task: • 1. pulmonary ventilation • 2. external respiration • 3. internal respiration

  22. Pulmonary Ventilation (breathing) • 1. inspiration vs expiration • 2. atmospheric pressure • 3. intrapulmonic pressure • 4. pressure gradient

  23. Thoracic Cavity Dimensions

  24. Inspiration (Active) • 1. Boyle's law • 2. inspiratory muscles • 3. phrenic nerve (C3-5) • 4. process thoracic volume pleural volume intrapleural pr. lung volume intrapulmonic pr. air flows into lungs Decrease volume increase pressure Increase volume decrease pressure

  25. Inspiration (Active) • 1. Boyle's law • 2. inspiratory muscles • 3. phrenic nerve (C3-5) • 4. process thoracic volume pleural volume intrapleural pr. lung volume intrapulmonic pr. air flows into lungs

  26. Expiration (passive) • 1. elastic recoil • 2. surface tension • 3. process thoracic volume pleural volume intrapleural pr. lung volume intrapulmonic pr. air flows out

  27. Forced Expiration

  28. Compliance -- the ease with which the lungs and thoracic wall can be expanded. • It is related to two factors: 1. elasticity 2. surface tension • Compliance is decreased with any condition that: 1. destroys lung tissue (emphysema) 2. fills the lungs with fluid (pneumonia) 3. produces a deficiency of surfactant (premature birth, near-drowning) 4. interferes with lung expansion (pneumothorax)

  29. Pulmonary Volumes and Capacities • 1. clinical respiration • 2. tidal vol. (500 ml) • 3. anatomic dead space (150 ml) • 5. inspiratory reserve volume (3,000 ml) • 6. expiratory reserve volume (1,200 ml) • 7. residual volume(1,300 ml) • 8. vital capacity (4,700 ml) • Rates maximum voluntary ventilation = TV x breaths/minute alveolar ventilation rate = alveolar ventilation x breaths/minute

  30. Exchange of Oxygen and Carbon Dioxide • 1. O2 flows down its concentration gradient by diffusion: alveoli ---> blood ---> interstitial fluid ---> body cells • 2. CO2 flows down its concentration gradient by diffusion: cells ---> interstitial fluid ---> blood ---> alveoli • 3. diffusion is dependent upon Dalton'slaw

  31. Dalton's law = each gas in a mixture of gases exerts its own pressure as if all of the other gases were not present. • 1. The pressure of a specific gas is known as its partial pressure (p). • 2. The total pressure of a mixture is the sum of all the partial pressures. • 3. Atmospheric air pressure = 760 mm Hg nitrogen = 597 mm Hg + oxygen = 159 mm Hg + carbon dioxide = 0.3 mm Hg + water vapor = 3.7 mm Hg

  32. PARTIAL PRESSURES OF OXYGEN alveolar air = 104 mmHg EXTERNAL RESPIRATION deoxygenated (pulmonary arterial) blood = 40 mmHg oxygenated (systemic arterial) blood = 104 mmHg interstitial fluid = 40 mmHg INTERNAL RESPIRATION cytoplasm = <40 mmHg

  33. PARTIAL PRESSURES OF CARBON DIOXIDE alveolar air = 40 mmHg EXTERNAL RESPIRATION deoxygenated (pulmonary arterial) blood = 46 mmHg oxygenated (systemic arterial) blood = 40 mmHg interstitial fluid = 46 mmHg INTERNAL RESPIRATION cytoplasm = >46 mmHg

  34. External (Pulmonary Respiration) • 1. alveoli <---> blood a. deoxygenated ---> oxygenated blood b. loss of CO2 • 2. diffusion 100% of time • 3. rate dependent upon: a. partial pr. differences b. surface area c. diffusion distance d. breathing rate and depth

  35. Internal (Tissue Respiration) • 1. blood <---> tissue fluid <---> cells a. oxygenated ---> deoxygenated (only 25% O2 given up) b. gains CO2 • 2. diffusion 100% of time

  36. Oxygen Transport 1. 98.5% as oxyhemoglobin 2. fully saturated vs partially saturated 3. percent saturation of HB 4. O2 - Hb dissociation curve 5. pO2 most important factor 100% 100% oxygen released to tissues at rest oxygen released to tissues during exercise 80% 80% 60% 60% oxygen saturation oxygen saturation 40% 40% 20% 20% 20 60 100 PO2 (mmHg) 20 60 100 PO2 (mmHg) 23% 73% 98% 98% 75% 25% LUNGS TISSUES LUNGS TISSUES

  37. Oxygen Transport Con’t • 6. Hb saturation and pH (Bohr effect) • 7. Hb saturation and pCO2 • 8. Hb saturation and temperature curve shifts to right when: pH decreases, PCO2 increases, temp. increases curve shifts to left when: pH increases, PCO2 decreases, temp. increases

  38. Carbon Dioxide Transport • 1. 5% dissolved in plasma, 7% exhanged • 2. 5% as carbamino-Hb, 23% exchanged • 3. 90% as bicarbonate ion, (HCO3-) 70% exchanged a. carbonic anhydrase b. Bohr effect c. chloride shift CO2 + H2O H2CO3 H+ + HCO3- Carbonic anyhydrase

  39. IN THE TISSUES SUMMARY H ion binds Hb in RBC and causes oxygen release (Bohr effect) diffuses from tissues into blood (RBCs) CO2 + H2O H2CO3 H+ + HCO3_ diffuses into plasma in exchange for chloride ions (chloride shift)

  40. Systemic Gas Exchange (in the Tissues)

  41. IN THE LUNGS SUMMARY H ion released from Hb into RBC cytoplasm diffuses into alveoli and breathed away CO2 + H2O H2CO3 H+ + HCO3- diffuses into RBC from plasma in exchange for chloride ions

  42. Alveolar Gas Exchange (in the lungs)

  43. Respiratory Centers • In the medulla • Dorsal Respiratory Group • Ventral Respiratory Group • Inspiratory neurons • Expiratory neurons • In the pons • Pneumotaxic Area • Apneustic Area

  44. Control of Respiration RESPIRATION AT REST active 2 seconds inactive 3 seconds inspiratory neurons diaphragm and external intercostals contract diaphragm and external intercostals relax + elastic recoil and surface tension effects normal resting inspiration normal resting expiration FORCED RESPIRATION diaphragm, external intercostals, scalenes, sternocleidomastoid contract forced inspiration DRG and inspiratory neurons active DRG and inspiratory neurons inhibited expiratory neurons of VRG inhibited inspiratory muscles relax expiratory neurons of VRG active internal intercostals and abdominal muscles contract active expiration

  45. Control of Respiration Continued • Pons controls transition between inhalation and exhalation A. Pneumotaxic center (overides apneustic) - sends inhibitory impulses to inspiratory area which shortens duration of inhalation before lungs get too full • Apneustic area - sends stimulatory impusles to the inspiratory area. Prolongs inhalation.

  46. Other influences on Respiration cerebral cortex limbic system hypothalamus sleep, exercise, vocalizations, exercise, breath holding, emotional responses • cortical influences • (chemoreceptors (Co2, H+) • 2. Hering-Breuer inflation reflex • Proprioceptors • Pain receptors pons respiratory group ventral respiratory group dorsal respiratory group altered patterns of breathing

  47. Hyperventilation and Hypoventilation • What would be the net effect of hyperventilation? reaction shifts to the left H+ used to reform carbonic acid used to reform CO2 pH increases increased CO2 lost from the body • What would be the net effect of hypoventilation? • reaction shifts to the right as CO2 accumulates in the body • H+ accumulate in the body • pH decreases CO2 + H2O H2CO3 H+ + HCO3- CO2 + H2O H2CO3 H+ + HCO3-

  48. Negative Feedback Control CONTROLLED CONDITION A stimulus or stress disrupts homeostasis by causing a decrease in arterial oxygen and/or increase in hydrogen ions and/or an increase in carbon dioxide RETURN TO HOMEOSTASIS Hyperventilation results in increase in arterial oxygen and/or pH, and/or decrease in arterial carbon dioxide RECEPTOR Chemosensitive neurons in medulla and chemoreceptors in aortic and carotid bodies respond to changes and direct nerve impulses to the control center EFFECTORS Muscles of inspiration contract more often and more forcefully (hyperventilation) CONTROL CENTER Inspiratory neurons of medulla interpret sensory input and generate nerve impulses that pass ultimately to effectors

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