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Lesson # 14. The Respiratory System 3. Chapter 23. Objectives:. 1-Define partial pressure and discuss its relationships to a gas mixture such as air. 2- Discuss how partial pressure affects gas transport by blood. . 3- Describe the mechanism of transporting O 2 and CO 2 .
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Lesson # 14 The Respiratory System 3 Chapter 23 Objectives: 1-Define partial pressure and discuss its relationships to a gas mixture such as air. 2- Discuss how partial pressure affects gas transport by blood. 3- Describe the mechanism of transporting O2 and CO2 . 4- Describe the factors that govern gas exchange in the lungs and systemic capillaries.
Gas Exchange External Respiration O2 CO2 O2 • It is the loading of O2 and unloading of CO2 at the pulmonary capillaries (gas exchange). O2 O2 CO2 CO2 O2 Gas Exchange occurs between blood and alveolar air and across the respiratory membrane. O2 CO2 Internal Respiration O2 CO2 It is the unloading of O2 and loading of CO2 at the systemic capillaries. O2 O2 CO2 CO2 Gas Exchange occurs between blood and interstitial fluid across the capillary endothelium. O2 CO2 CO2 O2 Gas exchange depends on the partial pressures of the gases and the diffusion of molecules between gas and liquid. CO2 CO2
The Gas Laws Henry’s Law: • When gas under pressure comes in contact with liquid, gas dissolves in liquid until equilibrium is reached. • The gas moves from the area of higher partial pressure to the area of lower partial pressure. • At a given temperature, the amount of a gas in solution is proportional to partial pressure of that gas. Lower concentration Higher concentration Diffusion of a solid in liquid.
External Respiration O2 O2 O2 O2 O2 CO2 O2 CO2 O2 CO2 O2 CO2 CO2 CO2 CO2 O2 O2 CO2 CO2 CO2 Internal Respiration
Oxygen Transport Alveolus External Respiration: PO2 PO2 = 100 = 40 • It is the loading of O2and unloading of CO2at the pulmonary capillaries. O2 Loading of O2 Partial pressure of O2 in the alveolar air: 100 mm Hg Pulmonary capillary Partial pressure of O2 in the plasma of the pulmonary capillaries: 40 mm Hg 1- O2 from alveolar air diffuses to the plasma and travels as dissolved gas (1.5% of O2) 2- O2 from alveolar air diffuses to the plasma and binds to the Deoxyhemoglobin (98.5% of O2) + O2 Deoxyhemoglobin (HHb) + H+ Oxyhemoglobin (HbO2) (98.5% of O2) (from alveolar air) • As Hb loads O2 its affinity for H+decreases, H+dissociates from Hb. Those H+ will bind to HCO 3-to help in CO2 unloading. CO2 • HCO 3- + H+ CO2 + H2O H2CO3
Oxygen Transport Intersticial fluid Alveolus Internal Respiration: PO2 PO2 = 95 = 40 • It is the unloading of O2andloading of CO2at the systemic capillaries. O2 Unloading of O2 Partial pressure of O2 in the interstitial fluid: 40 mm Hg Partial pressure of O2 in the plasma of the systemic capillaries: 95 mm Hg Systemic capillary 1- O2 dissolved in plasma as gas diffuses to the tissues (1.5% of O2) • H++ Oxyhemoglobin (HbO2) Deoxyhemoglobin (HHb) + O2 (98.5% of O2) (to the tissues) Oxyhemoglobin (HbO2) reduces its affinity for O2 due the H+released by H2CO3 CO2 + H2O H2CO3 • HCO 3- + H+ CO2
Carbon Dioxide Transport Alveolus External Respiration: PCO2 PCO2 = 40 = 45 • It is the loading of O2 and unloading of CO2at the pulmonary capillaries. Unloading of CO2 Partial pressure of CO2 in the alveolar air: 40 mm Hg Pulmonary capillary Partial pressure of CO2 in the plasma of the pulmonary capillaries: 45 mm Hg 1- Unloading of CO2 carried by HCO3- (70% of CO2) • HCO 3- + H+ H2CO3 CO2 + H2O (70% of CO2) (to alveolar air) 2- Unloading of CO2 carried by Carbaminohemoglobin and other carbamino- compounds (23% of CO2) Hemoglobin (Hb) + CO2 Carbaminohemoglobin (HbCO2) (to alveolar air) CO2 3- CO2 as dissolved gas (7% of CO2) diffuses from plasma to the alveolar air.
Carbon Dioxide Transport Intersticial fluid Alveolus Internal Respiration: PCO2 PCO2 = 40 = 45 • It is the unloading of O2 andloading of CO2at the systemic capillaries. O2 Loading of CO2 Partial pressure of CO2 in the interstitial fluid: 45 mm Hg Partial pressure of CO2 in the plasma of the systemic capillaries: 40 mm Hg Systemic capillary 1- Loading of CO2 to HCO3-(70%) CO2 + H2O H2CO3 • HCO 3- + H+ (from tissues) (70% of CO2) Carbonic anhydrase 2- Loading of CO2 to Hemoglobin (23%) Carbaminohemoglobin (HbCO2) CO2 + Hemoglobin (Hb) (23%) of CO2 (from tissues) 3- CO2 from tissues diffuses to the plasma and travels as dissolved gas (7% of CO2) CO2
External Respiration O2 from alveolar air diffuses to the plasma and travels as dissolved gas (1.5% of O2) Loading of Oxygen O2 from alveolar air diffuses to the plasma and binds to the Deoxyhemoglobin (98.5% of O2) 2 1 3 3 2 1 2 2 1 1 Unloading of Carbon Dioxide Unloading of CO2 carried by HCO3- (70% of CO2) Unloading of CO2 carried by Carbaminohemoglobin and other carbamino-compounds (23% of CO2) CO2 as dissolved gas (7% of CO2) diffuses from plasma to the alveolar air.
Internal Respiration O2 dissolved in plasma as gas diffuses to the tissues (1.5% of O2) Unloading of Oxygen Unloading of O2 bind to Oxyhemoglobin (98.5%) 2 1 3 3 2 1 2 2 1 1 Loading of Carbon Dioxide Loading of CO2 to HCO3-(70%) Loading of CO2 to Hemoglobin (23% of CO2) CO2 from tissues diffuses to the plasma and travels as dissolved gas (7% of CO2)
Coupling of CO2 - O2 Exchange 1- External Respiration + H+ Oxyhemoglobin (HbO2) Deoxyhemoglobin (HHb) + O2 + H+ (98.5% of O2) (from alveolar air) (to alveolar air) Loading of O2releasesH+from Deoxyhemoglobin. Those H+ bind to HCO 3-and help in CO2 unloading • HCO 3- H2CO3 CO2 + H2O (70% of CO2) 2- Internal Respiration + H+ • HCO 3- H2CO3 CO2 + H2O + H+ (70% of CO2) (from tissues) carbonic anhydrase • Oxyhemoglobin (HbO2) Deoxyhemoglobin (HHb) Loading of CO2releasesH+from H2CO3. Those H+ reduces the affinity of Oxyhemoglobin (HbO2) for O2 and help in O2 unloading + O2 (98.5% of O2) (to tissues)
