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Understanding Lung Ventilation and Perfuson: Practical Insights

Explore the intricate relationship between lung ventilation, perfusion, minute ventilation, and metabolic activity. Learn about factors influencing ventilation and critical thresholds in oxygen consumption during exercise.

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Understanding Lung Ventilation and Perfuson: Practical Insights

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  1. Breathing_practical class ? lung ventilation ? lung perfusion

  2. ventilation perfusion

  3. Ventilation Minute ventilation = breath frequency x air volume (balanced) spontaneous ~15 x ~500 ml = 7,5-8,0 L/min maximum ~ 150 L/min Minute ventilation is influenced by * pCO2 in arterialblood (central receptors - influence rate of firing of neurons in respiratory centers in medula -exciting other portions of respiratory center (dorsal respiratory, ventral respiratory, pneumotaxic, etc.) CO2 + H2O -> H+ + HCO3- *pO2 - periphery receptors (aortic, carotid bodies) - only when pO2 decreases from 100 mmHg to 60 mmHg * Temperature - diffusion rate Low pH ->increased expiration of CO2 -> regulation of pH

  4. Ventilation vs. body load VE (ml/min) V1 V2 Body load - O2 consumption => alveolar ventilation or alv pCO2 1 2 pCO2 -> breathing stimulant => lung ventilation pCO2 Minute ventilation = frequency x volume (balanced) spontaneous ~15 x ~500 ml = 7,5-8,0 L/min maximum ~ 150 L/min constant metabolic activity - constant amount of CO2 expired amount of expired CO2 = volume x pCO2 (concentration) The same amount of CO2 is possible to expire by increased ventilation and low concentration or low ventilation and high concentration body load All CO2 produced by body has to be expired, so insufficient ventilation leads to hyperkapnia (high pCO2)

  5. Consumption of O2 during load Maximal O2 uptake(VO2max)- the highest rate at which oxygen can be taken up and used by the body during severe exercise(ml/kg/min or L / min - absolute uptake) Mean value of VO2max : Regular population: mencca 45 ml/kg/min, females 35 ml/kg/min (normal) Top sportsmen (appropriate training): men more than 78 ml O2/kg/min,females over 68 ml O2/kg/min Lactate - concentration 0,5-2,2 mmol/L in human body (no load) Amount of lactic acid in blood during intensive work load depends on the type of metabolism (system used for energy production): < 2 mmol/l aerobic (slow glycolysis, oxidative metabolism)  3 – 7 mmol/l aerobic-anaerobic (slow- fast glycolysis)  > 7 mmol/l anaerobic (fast glycolyses, glycogene system)

  6. Anaerobic zone Aerobic-anareobic zone Aerobic zone lactate load (W) Dynamic of load indicators during excercise VO2max - maximal O2 uptake, SF- cardiac frequency, ANP - anaerobic threshold, KR - critical intensity of a load

  7. Respiratory quotient (RQ) = CO2/O2 expiredCO2 /inspiredO2 CO2output / O2 input RQ depends on the intensity of the work RQ gives an information about foodcomposition (type of metabolism used for energy): oxidation1 molecule of glucose (C6H12O6) requires 6 molecules of O2 - 6 molecule of CO2 released =>RQ = 1 Feat acids (lactic acid)- oxidation of 6*CH2 (C6H12) - requires 9 mol. O2 - 6 CO2 released =>RQ = 6/9 Respiratoryquotient/different kind of metabolism: RQ metabolism 1,0 sacharides 0,9 sacharides-fats 0,8 fats-sacharides 0,7 fats

  8. If consumptionof O2 is 50% to 60% of VO2max(trained persons 70-80%) - anareobic metabolism take place, lactate in the blood increases during excercise (H+, pH…) - CO2 HCO3- D RQ represents the percentual participation of anaerobic glycolysis in the total energy expediture RQ is over 1 at heavy work loads Time course of RQ during heavy work load RQ = CO2/O2 3 phases: a) initial increase (greater anaerobic glycolysis, increased formation of lactate) b) secondary drop (slower anaerobic glycolysis -increased O2 supply- temporary more lactic acid eliminated than formed) c) a continuous rise to a steady state (after approx. 3.5-4 min) (correlation with lactic acid level in the blood)

  9. 1. Spiroergometry the aim -to understand why the R.Q. during physical stress changes. expiredCO2 /inspiredO2 The Gas Analyzer has an infra-red transducer to measure CO2 concentration and a visible spectrum transducer to measure oxygen concentration Spirometer and attached flow head together function as a pneumotachometer, with an output signal proportional to the airflow rate during breathing. the load on the bicycle ergometer increase in a step-wise manner. • Questions • Which factors influence the respiratory quotient? • Explain differences in R.Q. during normal ventilation and higher physical exercise.

  10. 2. Spirometry The aim -to understand pCO2 and minute ventilation dependence. Spirometer and attached flow head together function as a pneumotachometer Expired or inspired air passes through avery fine wire mesh in the flow head. This creates a pressure differential between the two sides of the mesh proportional to the flow rate of the air passing through the flow head. Volume x respiratory rate = Minute Ventilation integration of expiratory flow gives the volume. • Questions • Explain why during hyperventilation CO2 at the end of expiration decreases? • Explain the differences between changes of CO2 in hyperventilation and in increased minute ventilation as a result of physical exercise. • 3. How does CO2 output change during the test?

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