赖蒽茵 浙江大学医学院生理系 求是特聘教授 浙江省“千人计划”人才， 博导 laienyin@zju

1. Respiratory Physiology（呼吸生理学） 赖蒽茵 浙江大学医学院生理系 求是特聘教授 浙江省“千人计划”人才，博导laienyin@zju.edu.cn May 26 and 27, 8:00 – 9:35 am, 基础医学各论 I 紫金港校区西2-303, 2012级五年制临床, 共162人

2. Respiratory Exchange of oxygen (O2) and carbon dioxide (CO2) with environment

3. Pulmonary ventilation 气体经呼吸道进出肺的过程 The process of moving air into and out of the lungs

4. Pulmonary ventilation 呼吸过程中肺内压的变化 吸气时，肺内压为 -2 to -1mmHg 尽力吸气时 (-100 to -30mmHg） 呼气时，肺内压为 1 to 2 mmHg 尽力呼气时 （60 to 140mmHg）

5. Thorax • The thorax is a closed compartment that is bounded at the neck by muscles and connective tissue and completely separated from the abdomen by the diaphragm.

6. Mechanics of pulmonary ventilation Muscles that cause lung expansion and contraction 吸气肌：diaphragm (膈肌) external intercostals (肋间外肌) 呼气肌：abdominal muscles (腹肌) internal intercostals (肋间内肌)

7. Structures of pulmonary ventilation

8. Breathing is an active process To inhale • Contraction of external intercostal muscles →elevation of ribs & sternum →increased front-to-back dimension of thoracic cavity →lowers air pressure in lungs →air moves into lungs • Contraction of diaphragm →diaphragm moves downward →increases vertical dimension of thoracic cavity →lowers air pressure in lungs →air moves into lungs

9. •To exhale Relaxation of external intercostal muscles & diaphragm →return of diaphragm, ribs, & sternum (胸骨) to resting position →restores thoracic cavity to pre-inspiratory volume →increases pressure in lungs →air is exhaled

11. Pattern of respiration •Abdominal breathing 腹式呼吸 •Thoracic breathing 胸式呼吸 •Eupnea平静呼吸 •Forced breathing 用力呼吸

12. Principles of pulmonary ventilation • Direct force of breathing • Pressure gradient between atmosphere and lung • Original force of breathing • Respiratory movement

13. Respiration A processes involved in exchange of oxygen (O2) and carbon dioxide (CO2) between an organism and the environment • Consist of • Inspiration: the inhalation of air into the lung • Expiration: breathing out

14. Respiratory system Upper airway Lower airway

15. The relaxation/contraction of circular smooth muscle lining these “airways’” determines how easily airflow can occur. Most gas exchange occurs in the alveolar sacs.

16. Four major steps of respiration • 1.Pulmonary ventilation • 2.Gas exchange • Lung • Tissue • 3.Gas transport in blood • 4.Cellular respiration

17. Respiratory process ｝外呼吸External respiration 气体在血液中的运输Gas transport in the blood ｝内呼吸Internal respiration

18. Process of respiration: Fig. 13.06

19. Tissue cells O2 CO2 O2 CO2 Tissue capillaries Gas exchange Pulmonary gas exchange Tissue gas exchange O2 CO2 CO2 O2 Pulmonary capillary

20. Principles of gas exchange • Diffusion: continuous random motion of gas molecules. • Partial pressure: the individual pressure of each gas, eg. PO2

21. Boyle’s law states that the pressure of a fixed number of gas molecules is inversely proportional to the volume of the container.

22. Laws governing gas diffusion • Henry’s law: The amount of dissolved gas is directly proportional to the partial pressure of the gas

23. Factors affecting gas exchange • D: Rate of gas diffusion • P: Difference of partial pressure • S: Solubility of the gas • T: Absolute temperature • A: Area of diffusion • d: Distance of diffusion • MW: Molecular weight

24. Gas partial pressure (mmHg) Atmosphere Alveoli Arterial Venous Tissue Po2 159 104 100 40 30 Pco2 0.3 40 40 46 50

25. In the lungs, the concentration gradients favor the diffusion of oxygen toward the blood and the diffusion of carbon dioxide toward the alveolar air. In the interface of the blood and the active cells, these gradients are reversed due to the metabolic activities of cells.

26. Pulmonary gas exchange factors • Thickness of respiratory membrane (呼吸膜) • Surface area of respiratory membrane • The diffusion coefficient of gas (扩散系数) • The pressure difference of gas between the two sides of membrane

27. Alveoli Each of the clustered alveoli includes an abundance of pulmonary capillaries, thereby assuring that the ventilated air is brought into close proximity to the “pulmonary” blood, allowing efficient and thorough gas exchange between the air and the blood.

28. Extensive branching of alveoli produces lots of surface area for exchange between air and blood. Alveolar and capillary walls are thin, permitting rapid diffusion of gases.

29. alveolus capillary endothelial cell surfactant CO2 epithelial cell O2 red blood cell interstitial space Respiratory membrane • Is the structure through which oxygen diffuse from the alveolus into the blood, and carbon dioxide in the opposite direction.

30. Gas transport in the blood • Respiratory gases are transported in the blood in two forms: • Physical dissolution • Chemical combination Alveoli Blood Tissue O2 →dissolve→combine→dissolve→ O2 CO2 ←dissolve←combine←dissolve← CO2

32. Transport of oxygen • Forms of oxygen transported • Chemical combination: 98.5% • Physical dissolution: 1.5% • Hemoglobin (血红蛋白，Hb) is essential for the transport of O2 by blood. (porphyrin molecules,卟啉分子)

33. Normal adult hemoglobin is composed of four subunits linked together, with each subunit containing a single heme -- the ring-like structure with a central iron atom that binds to an oxygen atom.

34. High PO2 Hb + O2 HbO2 Low PO2

35. Oxygen capacity 氧容量 • The maximal capacity of Hb to bind O2 in a blood sample • Oxygen content 氧含量 • The actual binding amount of O2 with Hb • Oxygen saturation 氧饱和度 • Is expressed as O2 bound to Hb devided by the maximal capacity of Hb to bindO2 • (O2 content / O2 capacity) x 100%

36. Hb >50g/L --- Cyanosis紫绀 • is a physical sign causing bluish discoloration of the skin and mucous membranes. • is caused by a lack of oxygen in the blood. • is associated with cold temperatures, heart failure, lung diseases. It is seen in infants at birth as a result of heart defects, respiratory distress syndrome, or lung and breathing problems. Hb + O2 HbO2

37. Cyanosis • Hb >50g/L

38. Carbon monoxide poisoning • CO competes for the O2 sides in Hb • CO has extremely high affinity for Hb • Carboxyhemoglobin---20%-40%, lethal (致命的). • A bright or cherry red coloration to the skin

39. Transport of carbon dioxide • Forms of carbon dioxide transported • Chemical combination: 93% • Bicarbonate ion (HCO3-) : 70% • Carbamino hemoglobin(氨基甲酸血红蛋白 ): 23% • Physical dissolve: 7%

40. Total blood carbon dioxide Sum of • Dissolved carbon dioxide • Bicarbonate • carbon dioxide in carbamino hemoglobin

41. CO2 transport in tissue capillaries tissues CO2 tissue capillaries CO2 CO2 + Hb HbCO2 carbonic anhydrase CO2 + H2O H2CO3 HCO3- H+ +HCO3- Cl- plasma tissuecapillaries

42. CO2 transport in pulmonary capillaries CO2 + Hb HbCO2 alveoli CO2 pulmonary capillaries CO2 carbonicanhydrase H2CO3 CO2 + H2O HCO3- H+ +HCO3- plasma Cl- Cl- pulmonary capillaries

44. Airflow (F) is a function of the pressure differences between the alveoli (Palv) and the atmosphere (Patm) divided by airflow resistance (R). Air enters the lungs when Palv < Patm Air exits the lungs when Palv > Patm

45. Intrapleural pressure （胸内压） Intrapleural pressure is the pressure within pleural cavity (胸膜腔)

46. Intrapleural pressure • Pleural cavity • Pleural cavity is the closed space between parietal pleura & lungs covered with visceral pleura

47. Intrapleural pressure the pressure within pleural cavity

48. Direct measurement of intrapleural pressure

49. Indirect measurement of intrapleural pressure • Measurement of the pressure inside the esophagus