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### 17 Cards in this Set

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 what gas mixtures make up the air inside a room Nitrogen (79%) O2 (21) what gas mixture makes up the air inside our airways N2, O2, and Vapro pressure if we breathe in 3600 ml of air, how do we determine the amount of air in the alveoli (vol inside the alveoli) the volumes inside the alveoli depends on the gases that are exchanged, only gases exchanged are O2 and Co2, N2 is ignored, the amount of O2 figured out by following: 3600X.21 (since O2 makes up 21%)= 756, we extract 250 ml so total amount of O2 in the alveolus is 756-250= 506ml N2 is 3600X.79= 2844ml Co2 is based on what's put inside the blood, w/c= 200ml if add all of these up we get total amount of Air inside the alveolus= 2844+506+200= 3550 To figure out the mole fractions (F)we use these #'s divided by 3550 e.g FO2= 556/3550= .142 FN2=2844/3550=.80 FCo2=200/3550=.06 TO CALCULATE THE PARTIAL PRESSURES OF ALL OF THESE GASES WE USE: PP=FXTotal Pressure PO2= .14X713= 102 PCo2= .80X713=571, we ignore the vapor pressure for simplicity when measuring alveolar ventilation where does the gas comes from? 2 places 1 dead space called VD 2 alveoli called VA, what does total ventilation or expired vol equal Vexpired= Vd+Va what is the key thing to remember w/Va and Vd since gase exchange only takes place in the alveoli, the dead space doesn't contribute much how is ventilation measured by getting a patient to slowly exhale, remembering that first burst of air expelled is from dead space, once the exhalation continues, it comes form the alveolus and that's what measured why is amount of gas breathed out smaller than amount breathed in b/c it depends in O2 breathed in. when we breathe in O2, it goes to Co2, 1 O2 yields 1 Co2, but some of the O2 also combines w/H to make H2O, so we breathe more O2 and it is divided into 2 places and we only exhale Co2, w/c is less O2 then we take in what is total/tidal minute ventilation it Vt= Vd+Va, it is usually measured by taking into account the frequency (F) of breaths/minute, so its actually: VtF=VdF+VaF, it is always denoted w/a dot what does total minute ventilation tell us it tells us the fraction of ventilation that goes to the dead space and the amount that goes the actual exchange area or alveolus what is Alveolar Gas eq 1 PaCo2~ VCo2/Va according to the alveolar gas eq 1, what does the PaCo2 depend on it is dependent on Vol of Co2 (directly) and amount of ventilation (inversely) what happen to PaCo2 when hyperventilate Hypoventilate PaCo2 decreases PaCo2 Increase, assuming that vol of Co2 stays constant what is alveolar gas equation 2 PAO2= PIo2-PaCO2/r r=0.8 PIo2= pressure of O2 inhlaed what is the purpose of this eqution this equation is there to assess the lung function in a patient what are the dead spaces 2 types 1)anatomical(large airways, not measured) 2)physiological(measured), this is usually strongly elevated in pulmonary embolus where are physiological dead spaces elevated anywhere there is high V?Q ratio or anywhere a tube is inserted in series w/a patients airways