2.3.2 Oxygen and Carbon Dioxide Transport Flashcards
In what two forms is oxygen transported through the body?
Dissolved in plasma and rbc water
Combined with Hb
What is equation for dissolved O2?
Dissolved O2 = PO2 * S
What is the solubility constant, S, for O2?
0.003 mL/dL/mm Hg
What is the normal oxygen consumption of the body?
250-300 mL O2/min
How much oxygen can 1 g of Hb hold?
1.34 mL O2
What is the normal amount of Hb (g) in the blood?
15 g of Hb
Blood PO2 is determined by what form of oxygen carried in the blood?
The O2 in the liquid phase (not attached to Hb)
What is the equation for O2 saturation of Hb (%)?
O2 saturation of Hb (%) = [(HbO2,ml/dl / (Hb, g/dl * 1.34 ml/g)] x 100
What is the equation for blood O2 content?
Blood [O2] content, ml/dl = [0.003 ml/(mmHg x dl) x PO2 (mmHg)] + [Hb] g/dl x 1.34 ml/g x % O2 sat]
Calculate and insert the remaining values
What is the normal PO2 in the arteries? veins?
PaO2 = 100 mm Hg
PvO2 = 40 mm Hg
Draw the oxygen dissociation curve of Hb with O2 saturation on the y-axis
What four changes can cause the red shift in the ODC of Hb? blue shift?
When trying to remember the changes that occur to cause the red shift, think of the changes that occur while working out
Drawing a variation of the ODC by plotting total blood O2 content vs PO2.
What is different about this curve from the ODC with O2 sat vs PO2?
Because dissolved oxygen is a now factor in the y-axis, the ODC curve will not level off. As PO2 rises, the amount of dissolved O2 in the blood willl continue to rise.
What is the equation for VO2?
VO2 = Q * C(a-v) O2
Q, cardiac output
C (a-v) O2, difference in arterial and venous O2 content
What is the equation for oxygen extraction ratio (O2ER)?
O2ER- C (a-v) O2/ CaO2
What are the three ways that CO2 can be transported?
- Physical solution. Dissolved CO2, mmol / L = 0.03 mmol/(L x mmHg)* PCO2, mmHg.
- Hydration of CO2, formation of carbonic acid and dissociation into bicarbonate and hydrogen ions
- Formation of carbamino compounds with plasma proteins and Hb.
Where is most of the bicarbonate produced then stored?
Most of the bicarbonate is produced within the RBC. It is then gets transported out of the RBC via a HCO3--Cl- exchanger and is stored in the plasma.
What enzyme plays an important role in the formation of bicarbonic acid from CO2 and water?
Carbonic Anhydrase
Draw the curve for CO2 saturation of Hb. Identify the HbO2 saturation at venous and arterial PCO2.
Draw the curve where arterial and venous blood O2 and CO2 content, in ml/dl, are plotted as a function of the respective partial pressures
