Respiratory physiology:

1. Respiratory physiology:

2. Respiration • Ventilation: Movement of air into and out of lungs • External respiration: Gas exchange between air in lungs and blood • Transport of oxygen and carbon dioxide in the blood • Internal respiration: Gas exchange between the blood and tissues

3. Respiratory System Functions • Gas exchange: Oxygen enters blood and carbon dioxide leaves • Regulation of blood pH: Altered by changing blood carbon dioxide levels • Voice production: Movement of air past vocal folds makes sound and speech • Olfaction: Smell occurs when airborne molecules drawn into nasal cavity • Protection: Against microorganisms by preventing entry and removing them

4. Respiratory System Divisions • Upper tract • Nose, pharynx and associated structures • Lower tract • Larynx, trachea, bronchi, lungs

5. Nasal Cavity and Pharynx

6. Nose External nose Nasal cavity Functions Passageway for air Cleans the air Humidifies, warms air Smell Along with paranasal sinuses are resonating chambers for speech Pharynx Common opening for digestive and respiratory systems Three regions Nasopharynx Oropharynx Laryngopharynx Nose and Pharynx

7. Larynx • Functions • Maintain an open passageway for air movement • Epiglottis and vestibular folds prevent swallowed material from moving into larynx • Vocal folds are primary source of sound production

8. Vocal Folds

9. Trachea • Windpipe • Divides to form • Primary bronchi • Carina: Cough reflex

10. Tracheobronchial Tree • Conducting zone • Trachea to terminal bronchioles which is ciliated for removal of debris • Passageway for air movement • Cartilage holds tube system open and smooth muscle controls tube diameter • Respiratory zone • Respiratory bronchioles to alveoli • Site for gas exchange

11. Tracheobronchial Tree

12. Bronchioles and Alveoli

13. Alveolus and Respiratory Membrane

15. Fig. 4. Effects of methacholine on depth of airway • surface liquid. a: control tissue not exposed to methacholine. • b: 2-min methacholine exposure. Putative • sol and mucous gel are clearly visible. c: 30-min • exposure. Tissues were radiant etched for 20 s to 1 • min. Scale bar 5 20 μm. • From Am. J. Physiol. 274 (Lung Cell. Mol. Physiol. 18): L388–L395, 1998.—

16. Lungs • Two lungs: Principal organs of respiration • Right lung: Three lobes • Left lung: Two lobes • Divisions • Lobes, bronchopulmonary segments, lobules

17. Thoracic WallsMuscles of Respiration

18. Thoracic Volume

20. Pleura • Pleural fluid produced by pleural membranes • Acts as lubricant • Helps hold parietal and visceral pleural membranes together

21. Ventilation • Movement of air into and out of lungs • Air moves from area of higher pressure to area of lower pressure • Pressure is inversely related to volume

22. Alveolar Pressure Changes

23. Changing Alveolar Volume • Lung recoil • Causes alveoli to collapse resulting from • Elastic recoil and surface tension • Surfactant: Reduces tendency of lungs to collapse • Pleural pressure • Negative pressure can cause alveoli to expand • Pneumothorax is an opening between pleural cavity and air that causes a loss of pleural pressure

24. Normal Breathing Cycle

25. Compliance • Measure of the ease with which lungs and thorax expand • The greater the compliance, the easier it is for a change in pressure to cause expansion • A lower-than-normal compliance means the lungs and thorax are harder to expand • Conditions that decrease compliance • Pulmonary fibrosis • Pulmonary edema • Respiratory distress syndrome

26. Pulmonary Volumes • Tidal volume • Volume of air inspired or expired during a normal inspiration or expiration • Inspiratory reserve volume • Amount of air inspired forcefully after inspiration of normal tidal volume • Expiratory reserve volume • Amount of air forcefully expired after expiration of normal tidal volume • Residual volume • Volume of air remaining in respiratory passages and lungs after the most forceful expiration

27. Pulmonary Capacities • Inspiratory capacity • Tidal volume plus inspiratory reserve volume • Functional residual capacity • Expiratory reserve volume plus the residual volume • Vital capacity • Sum of inspiratory reserve volume, tidal volume, and expiratory reserve volume • Total lung capacity • Sum of inspiratory and expiratory reserve volumes plus the tidal volume and residual volume

28. Spirometer and Lung Volumes/Capacities

29. Minute and Alveolar Ventilation • Minute ventilation: Total amount of air moved into and out of respiratory system per minute • Respiratory rate or frequency: Number of breaths taken per minute • Anatomic dead space: Part of respiratory system where gas exchange does not take place • Alveolar ventilation: How much air per minute enters the parts of the respiratory system in which gas exchange takes place

31. Physical Principles of Gas Exchange • Partial pressure • The pressure exerted by each type of gas in a mixture • Dalton’s law • Water vapor pressure • Diffusion of gases through liquids • Concentration of a gas in a liquid is determined by its partial pressure and its solubility coefficient • Henry’s law

36. Physical Principles of Gas Exchange • Diffusion of gases through the respiratory membrane • Depends on membrane’s thickness, the diffusion coefficient of gas, surface areas of membrane, partial pressure of gases in alveoli and blood • Relationship between ventilation and pulmonary capillary flow • Increased ventilation or increased pulmonary capillary blood flow increases gas exchange • Physiologic shunt is deoxygenated blood returning from lungs

37. Oxygen Moves from alveoli into blood. Blood is almost completely saturated with oxygen when it leaves the capillary P02 in blood decreases because of mixing with deoxygenated blood Oxygen moves from tissue capillaries into the tissues Carbon dioxide Moves from tissues into tissue capillaries Moves from pulmonary capillaries into the alveoli Oxygen and Carbon Dioxide Diffusion Gradients

38. Changes in Partial Pressures

40. Hemoglobin and Oxygen Transport • Oxygen is transported by hemoglobin (98.5%) and is dissolved in plasma (1.5%) • Oxygen-hemoglobin dissociation curve shows that hemoglobin is almost completely saturated when P02 is 80 mm Hg or above. At lower partial pressures, the hemoglobin releases oxygen. • A shift of the curve to the left because of an increase in pH, a decrease in carbon dioxide, or a decrease in temperature results in an increase in the ability of hemoglobin to hold oxygen

41. Hemoglobin and Oxygen Transport • A shift of the curve to the right because of a decrease in pH, an increase in carbon dioxide, or an increase in temperature results in a decrease in the ability of hemoglobin to hold oxygen • The substance 2.3-bisphosphoglycerate increases the ability of hemoglobin to release oxygen • Fetal hemoglobin has a higher affinity for oxygen than does maternal

42. Oxygen-HemoglobinDissociation Curve at Rest

43. Bohr effect:

44. Temperature effects:

46. Shifting the Curve

47. Transport of Carbon Dioxide • Carbon dioxide is transported as bicarbonate ions (70%) in combination with blood proteins (23%) and in solution with plasma (7%) • Hemoglobin that has released oxygen binds more readily to carbon dioxide than hemoglobin that has oxygen bound to it (Haldane effect) • In tissue capillaries, carbon dioxide combines with water inside RBCs to form carbonic acid which dissociates to form bicarbonate ions and hydrogen ions

49. Transport of Carbon Dioxide • In lung capillaries, bicarbonate ions and hydrogen ions move into RBCs and chloride ions move out. Bicarbonate ions combine with hydrogen ions to form carbonic acid. The carbonic acid is converted to carbon dioxide and water. The carbon dioxide diffuses out of the RBCs. • Increased plasma carbon dioxide lowers blood pH. The respiratory system regulates blood pH by regulating plasma carbon dioxide levels

50. Haldane Effect • The amount of carbon dioxide transported is markedly affected by the PO2 • Haldane effect – the lower the PO2 and hemoglobin saturation with oxygen, the more carbon dioxide can be carried in the blood