Section 2 Respiratory Gases Exchange

1. Section 2 Respiratory Gases Exchange

4. Partial pressure • The pressure exerted by each type of gas in a mixture • Partial pressure=total pressure x percent of volume • Diffusion of gases through liquids • Concentration of a gas in a liquid is determined by its partial pressure and its solubility.

11. Oxygen and Carbon Dioxide Diffusion Gradients • Oxygen • Moves from alveoli into blood. Blood is almost completely saturated with oxygen when it leaves the capillary • Oxygen moves from tissue capillaries into the tissues • Carbon dioxide • Moves from tissues into tissue capillaries • Moves from pulmonary capillaries into the alveoli

13. Capillary Basement membrane Epithelial Basement membrane 0.2micrometer

14. Diffusion distance—thickness of alveolar membrane (inverse ratio relationship) Pulmonary fibrosis---Thickness increases Pulmonary edema---Diffusion decreases ｝

15. Diffusion area of alveolar membrane : when diffusion area of alveolar membrane is large,it diffuses fast. • diffusion area of alveolar membrane is 40m2 in normal quiet state. • diffusion area of alveolar membrane is 70m2 during sports. • diffusion area of alveolar membrane decreases in disease.

16. Much gas or less blood little gas or Much blood V/Q↑ V/Q↓ alveolar dead space↑ arteriovenous shunt efficiency

17. partial alveolar gas can not exchange fully with the blood e.g. pulmonary embolism ventilation /perfusion ratio decreases: it means partial blood flow through hypoventilation alveoli. They can not get fully exchange. And it equals functional arteriovenous shunt.

18. 3.3 Upright position 0.63

19. Internal Respiration • All cells require oxygen for metabolism • All cells require means to remove carbon dioxide • Gas exchange at cellular level

20. Concept: Gas exchange between the capillary and the tissues throughout the body • Process: • Factors affecting the internal respiration: • Distance between the cells and the capillary • metabolic rate • Speed of the blood flow in capillary Interstitialfliud

21. Most of oxygen and carbon dioxide in the blood is transported in chemical combination Only the gas in physical dissolution express PP and diffuse to a place with low PP. Dynamic balance between the two forms: Physical dissolution Chemical combination PP PP

22. Content of O2 and CO2 in the blood （ml/100ml） arterial blood venous blood dissolve combine total dissolve combine total O2 0.31 20.0 20.31 0.11 15.2 15.31 CO2 2.53 46.4 48.93 2.91 50.0 52.91

25. each of which contains a heme attached to a polypeptide chain by a nitrogen atom to from one subunits of hemoglobin.

27. Oxygen

28. O2 + Hb HbO2 Oxyhemoglobin Formation • Oxyhemoglobin forms when an oxygen molecule reversibly attaches to the heme portion of hemoglobin. The heme unit contains iron ( +2 ) which provides the attractive force. • The process is summarized as follows:

29. character • 1. Reversible binding. Without enzyme. Fast. Effected by PO2. • In lungs, increasing of PO2 promotes combination. • In tissues, decreasing of PO2 promotes releasing.

31. reversible binding of Hb and O2 • O2 partial pressure is higher(lung) • Hb＋O2 HbO2 • O2 partial pressure is lower(tissues) deoxyhemoglobin 、royal blueOxyhemoglobin、red • molecular configuration : salt bond break • tense relaxed • salt bond form

32. Hb binds with O2 —salt bond breaks, R form，the affinity of R form to O2 is larger. Hb dissociates with O2—salt bond forms,T form，the affinity of T form to O2 is smaller.

34. character • 2.O2 binds with Fe2+ of ferrohemoglobin . The ion value is permanent. The iron stays in the ferrous state, So the process is called oxygenation but not oxidation.

35. 3. Globin of ferrohemoglobin is made up of two αpeptide chains and two β peptide chains . There is a heme molecular on each peptide chain including a Fe2+. Each Fe2+ binds with an O2 . • So each ferrohemoglobin can bind with four O2. （HbO8） • 1gHb can bind with 1.34－1.39mlO2.

36. In 15g/100ml blood , 1g Hb binds with 1.34ml O2. Oxygen capacity= 15×1.34＝20ml arterial blood: 20ml O2 venous blood: 15ml O2

37. Oxygen saturation: The percentage of oxygen content to oxygen capacity. In arterial blood, oxygen content equals 20ml and oxygen saturation is 100%. In venous blood , oxygen content equals 15ml and oxygen saturation is 75%.

40. 4. The binding or dissociation curves of Hb and O2 appear S form.This is related to the allosterism effect of Hb.

42. The oxygen-hemoglobin dissociation curve A. Flattened upper portion B. Steep middle portion C. Lower portion

43. Binding zone • Slope is flat. • 1） Partial pressure of oxygen is high， oxygenation saturation is also high. • 2） Partial pressure of oxygen changes greatly. But saturation changes little—even PO2 of environment or alveoli descents, oxygenation saturation will maintain high level. • When PO2＞100mmHg, rising of oxygenation saturation is not obvious . Rising of blood oxygen volume is little.

45. 2. Middle segment of curve: • PO2 60－40mmHg . HbO2 releases O2. • At this time Hb oxygen saturation is 75%, oxygen content in blood is 14.4mLO2. • In the other words, every 100ml blood releases 5mlO2 when it flows over tissues. • The percentage of oxygen capacity released when blood flows over tissues to oxygen content in arteria is called oxygen utilization coefficient. It is 25% in normal quiet state and it increases to 75% in sports.

46. The slope is steep. • PO2 descents a little. It makes oxygen dissociation saturation descent. This is benefit to supplying oxygen for tissue activity. Oxygen utilization coefficient increases to 75%. Storage of O2

50. Shifting the Curve