Video 3 Blood Gas transport Flashcards
What is the partial pressure of oxygen? How do you calculate it?
160 mmHg
0.21 (concentration of oxygen) x 760 mmHg (barometric pressure)
When air is inspired it is _______ and _______ and saturated with _________ at _______ degrees celcius.
warmed
moistened
water vapor
37
What is the partial pressure of water vapor at 37 degrees?
47 mmHg
What needs to be considered when calculating the partial pressure of oxygen? How is it calculated?
The inspired gas is moist, subtract the partial pressure of water vapor from the barometric pressure before multiplying by 0.21
760-47= 713 mmHg
0.21 x 713 mmHg= 150 mmHg
What is the partial pressure of oxygen in water if equilibrated to oxygen in air?
150 mmHg
What is the concentration of oxygen in air vs water? Why such a difference?
21 ml/dl vs 0.45 ml/dl
The solubility of oxygen in water is very low
PO2 in arterial blood
100 mmHg
Amount of oxygen dissolved in arterial blood
0.3 ml/dl OR 3ml/liter
Why isnt oxygen in solution sufficient for our tissues?
oxygen in transport (hemoglobin) is required because the maximum O2 available in solution is 90 ml/min assuming a cardiac output of 30 liters/min during exercise. The O2 requirement at that level is 3000 ml/min
Structure of hemoglobin
4 heme molecules, 4 polypeptide chains (2 alpha and 2 beta)
Hemoglobin A vs hemoglobin F
adult vs fetal
Fetal Hb has a high ______
oxygen affinity
Describe sickle cell hemoglobin
one chain is altered due to mutation
What is oxygen capacity?
The total amount of oxygen that the blood can carry attached to hemoglobin
Why is the oxygen dissociation curve sigmodoidal shaped?
due to the confirmation change the hemoglobin undergoes as oxygen attaches; after one oxygen molecule attaches, the affinity goes up
In arterial blood, with a PO2 of 100, what is the oxygen concentration?
Nearly 100% (97%)
What is mixed venous blood?
Blood in the pulmonary artery coming into the lung
Venous blood has a PO2 of _______ and an O2 saturation of ______
40 mmHg
75%
What is P50? What is the normal value in arterial blood?
Partial pressure of oxygen for 50% saturation
27 mmHg
How to calculate total oxygen concentration of blood
Total O2 = 1.39 x Hb x %saturation/100 + (0.003 x PO2)
How much oxygen can combine with hb?
one gram of Hb can combine with 1.39 ml of oxygen
Normal hemoglobin level
15 g/dl
Shifting the oxygen dissociation curve to the left has what effect on affinity
increased affinity; the oxygen saturation for a given PO2 is increased
What 4 factors shift the dissociation curve to the right?
- Temp
- increased P CO2
- increased H ion concentration
- increased 2,3 DPG
An exercising muscle favors a shift in what direction on the dissociation curve?
Shift to the right; want to unload more oxygen
what is 2,3 DPG
product of red cell metabolism
Describe CO affinity for hemoglin
extremely high; about 240 times that of oxygen
If 33% of Hb is bound to CO, does the affinity for oxygen increase or decrease? what effect does this have?
increase
It is difficult to unload the oxygen in the periphery
3 forms that carbon dioxide is carried in the blood
- dissolved
- as bicarb
- as carbamino compound
Compare the solubility of oxgyen to that of CO2
0.003 ml.dl vs 0.067 ml/dl
carbon dioxide combines with water to form? what enzyme helps speed up this reaction?
carbonic acid
carbonic anhydrase
Where does CO2 bind to Hb? what does it form?
terminal amine group
carbamino hemoglobin
T/F: Plasma contains carbonic anhydrase
False; it is only in red blood cells
carbonic acid dissociates to
bicarb and a Hydrogen ion
Reduced Hb combines with ______ much more easily than _______ Hb
protons
oxygenated
The lower the oxygen saturation in the blood, the better it is to take up?
CO2
What causes the chloride shift into the red blood cells?
The H ions inability to diffuse across the cell wall like bicarb after disassociation of carbonic acid . Chloride ions shift to balance the electronegativity
All of the processes happening in the RBC cause?
water to shift into the cell due to the increased osmolarity
Of the 3 forms of CO2 carriage in arterial blood, which is the most prevalent? What about mixed blood?
90% is carried by bicarb. Bicarb is also most prevalent in mixed blood, however the percentage is 60%
Why it a result of a more linear and steeper CO2 dissociation curve when compared to oxygen?
The difference in partial pressure between the arterial and the mixed venous blood is much less for CO2 than oxygen
What is the Boehr effect?
Reducing CO2 increases oxygen affinity
