dr andreas lecture 12 re-upload

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Respiratory physiology awh 02[1] تعديل

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dr andreas lecture 12 re-upload

  1. 1. 3/18/2013 Respiratory Physiology Lecture 2 Andreas W. Henkel, Ph.D. Diagnosis of lung malfunctionRespiration Exhalevolume Inhale L/sec L/sec Inspiratory reserve vol. Tidal vol. Exspiratory reserve vol. Residual vol. Respiration speed 1
  2. 2. 3/18/2013Diagnosis of lung malfunctionDiagnose stenoses with spirometer: No change in any volume Slower inhalation speed Slower exhalation speedDiagnosis of lung malfunction Inspiratory reserve Tidal Exspiratory reserve residual 2
  3. 3. 3/18/2013Diagnosis of lung malfunctionDiagnose obstruction with spirometer: Residual volume is slightly increased Expiratory reserve volume is slightly increased Inspiratory reserve volume is slightly decreased Little slower inhalation speed Slower exhalation speed Diagnosis of lung malfunction Inspiratory reserve Tidal Exspiratory reserve residual 3
  4. 4. 3/18/2013 Diagnosis of lung malfunctionDiagnose Emphysema with spirometer: Residual volume is largely increased Expiratory reserve volume is slightly increased Inspiratory reserve volume is largely decreased Little slower inhalation speed Much slower exhalation speed Diagnosis of lung malfunction Inspiratory reserve Tidal Exspiratory reserve residual 4
  5. 5. 3/18/2013 Diagnosis of lung malfunction Diagnose Restriction with spirometer: Expiratory reserve volume is decreased Inspiratory reserve volume is decreased Little slower inhalation speed Little slower exhalation speed Gas partial pressureAtmospheric pressure at sea level :760 mm Hg (Mercury) = 760 torr= 1013 millibarDalton’s law:Pressure is sum of partial pressuresPartial pressure O2 =760 * 0.21 = 159100 % water saturation at 37 C= 47 mm HgThe colder the water, the more gas can bedissolvedSolubility depends on gas type 5
  6. 6. 3/18/2013 Gas partial pressureNitrogen (N2) 78.1%Oxygen (O2) 20.9%Argon (Ar) 0.9%Carbon dioxide (CO2) 0.038%Neon (Ne) 0.002%Helium (He) (0.000524%) Methane (CH4) 1.79 (0.000179%) , Krypton(Kr) (0.000114%) , Hydrogen (H2) (0.000055%) ,Nitrous oxide (N2O)(0.00003%), Xenon (Xe) (9 × 10−6%), Ozone (O3) (0% to 7 × 10−6%),Nitrogen dioxide (NO2) (2 × 10−6%), Iodine (I) (1 × 10−6%), Carbonmonoxide (CO) ,Ammonia (NH3) trace Pressure distribution in the atmosphere human live zone 6
  7. 7. 3/18/2013Respiratory zone anatomy Alveolar air 7
  8. 8. 3/18/2013 Calculation of alveolar O2 Sample values given for air at sea level at 37°C . Quantity Description Sample value pAO2 The alveolar partial pressure of oxygen (pO2) 107 mmHg The fraction of inspired gas that is oxygen FIO2 0.21 (expressed as a decimal). PATM The prevailing atmospheric pressure 760 mmHg The saturated vapour pressure of water at pH2O body temperature and the prevailing 47 mmHg atmospheric pressure The arterial partial pressure of carbon paCO2 36 mmHg dioxide (pCO2) RQ The respiratory quotient (CO 2/O2) 0.8 Calculation of alveolar O2The respiratory quotient (RQ) iscalculated from the ratio: RQ = CO2 eliminated / O2 consumedcarbon dioxide (CO2) removed"eliminated“ from the body. 8
  9. 9. 3/18/2013Calculation of alveolar O2 in La PazCalculation of alveolar O2 in La Paz Air pressure at 3640 m = 484 torr Water vapor in alveoli = 100 % = 47 torr CO2 - pressure in air ~ 0 torr CO2 - pressure in alveoli = 42 torr Fraction of O2 in air = 0.21 = 21 % Respiratory quotient = 0.8 PalveolarO2 = 0.21 *(484 – 47) – (42/0.8) = 39.27 torr 9
  10. 10. 3/18/2013 Respiratory zone Blood Alveolar air Respiratory membrane Gas exchange across this surface takes place driven entirely by DIFFUSION.Diffusion and respiratory functionGas exchange acrossrespiratory membranes-Differences in partial pressure-Small diffusion distance-Lipid-soluble gases-Large surface area of all alveoli-Coordination of blood flow and airflow 10
  11. 11. 3/18/2013 Blood gas transport O2 is carried in the blood as: 1. Dissolved gas (in plasma) 2. Bound to hemoglobin as oxyhemoglobin (Hb O2). Blood Alveoli Hemoglobin Hemoglobin is composed of protein (globin) and heme-groups4 globins and 4 hemes = 1 hemoglobin molecule O2 Heme-group contains Fe2+ Remember! 1 O2 binds to 1 Fe 11
  12. 12. 3/18/2013Oxygen binding to hemoglobin changes its structure Blood O2 transport by hemoglobin 4th O2 3rd O2 2nd O2 Cooperative binding of O2 1st O2 to hemoglobin 12
  13. 13. 3/18/2013 O2 content in bloodCalculation:Concentration of Hb in blood 110 -180 gNormal Hb-saturation = 97%1 g Hb can bind max. 1.34 ml O2Total O2 in blood = Hb-bound + free O2= Hb max * saturation [%] + free O2 Gas transport controlpHCO2TemperatureDPG (2,3-Bisphosphoglyceric acid) makes it harder for oxygen to bind hemoglobin and more likely to be released to adjacent tissues 13
  14. 14. 3/18/2013 Control of O2 in the blood CyanosisHow can you get blue blood ?Inhibit hemoglobin binding capacity by carbonmonoxid (250 times better binding to Hb)Central cyanosisventilatory problemslowing down of circulationPeripheral cyanosispoor circulation in the small vessels 14
  15. 15. 3/18/2013 Oxygen DeliveryOxygen Delivery (DO2)- Cardiac output (Qt)- Hb content of blood- Ability of the lung to oxygenate the bloodTotal O2 delivered = Qt * O2 in arterial blood.Qt = 5 L / minute, alveoloar O2 = 20 %;Lungs deliver 1 L of O2 to our tissues each minute. CO2 transport in blood CO2 is transported in blood… as HCO3- ion = bicarbonate (90 %) as dissolved CO2 (5 %) as carbamino protein complexes (5 %) Predominant transport mechanism of CO2 is as HCO3- within the red blood cells 15
  16. 16. 3/18/2013 CO2 transport in bloodCO2 is transported as carbonate ionCO2 + H2O H2CO3 H+ + HCO3-Enzyme is Carbonic Anhydrase in RBCChloride shift to compensate forbicarbonate moving in and out of RBCEnzymatic conversion of CO2 16
  17. 17. 3/18/2013 Regulation of breathing Two major descending pathways from the Medulla oblongata: 1. voluntary breathing 2. involuntary breathing Controls of respiration Input 1Input consists of 3 Input 2 Input 3 components:1. The central & peripheral Medulla oblongata in the brainstem chemo receptors (input 1) (integrator)2. The pulmonary mechanoreceptors (input 2) Output (via phrenic nerve)3. Input from reticular activation system, cerebral Respiratory muscles cortex, thalamus (input 3) 17
  18. 18. 3/18/2013Brain stem breathing centers Rhythmic center in formatio reticularis of medulla oblongata I-neurons (inspiration) stimulate spinal motoneurons E-neurons (expiration) inhibit I-neurons Apneustic centre stimulates I-neurons Pneumotactic centre inhibits apneustic centre Chemo receptors provide sensory input O2, CO2 and pH are monitored Arterial CO2 is the most important! 1. Central chemo receptors in Medulla oblongata 2. Peripheral chemo receptors (aortic und carotid bodies) provide indirect input to Medulla oblongata 18
  19. 19. 3/18/2013 Motoric innervations of muscles Cortical input (voluntary)Ventilation, regulated by pH & CO2 19
  20. 20. 3/18/2013 Blood gas abnormalitiesOxygen toxicity:100 % oxygen at 760 – 1500 mm Hg OK!higher pressure > 1800 mm Hg enzyme andnerve damageNitrogen narcosis (rapture of the deep):long term exposure to high pressure >2500mm Hg for > 1 hlike alcohol intoxication Blood gas abnormalitiesDecompression sicknessOnly happens after prolonged stay athigh pressure.Nitrogen forms bubbles, when a diverascents to fast.Obey decompression tables 20
  21. 21. 3/18/2013 Blood gas abnormalities Stagnant hypoxia: intravascular stasis. Decreased venous outflow of blood from tissue. Anemic hypoxia: decreased concentration of functional hemoglobin or low RBC count Hypoxic hypoxia: defective mechanism of oxygenation in the lungs Blood gas abnormalitiesArterial hypoxemia : arterial PaO2 is to low.An arterial PaO2 less than 80 mm Hg is abnormalHypoxia: insufficient oxygen to carry out normalmetabolic functions. Thus, hypoxia and hypoxemiaare frequently used interchangeably.Hypercapnia : increase in arterial PaCO2 above 40 ±2 mm HgHypocapnia : abnormally low arterial PaCO2 (lessthan 35 mm Hg). 21

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