Respiratory 5&6 Flashcards
Solubility coefficient of oxygen?
0.003 mL/mmHg/100mL of blood
Bulk of oxygen blood is carried bound to _____
hemoglobin
What does pO2 represent?
Amount of o2 dissolved in blood
Heme is an ____ ____ compound
iron-porphyrin
What does heme consist of?
- Joined to progtein globin with 4 peptide chaines
- 2 alpha and 2 beta (adult Hb of HbA)
- Hemoglobin A is adult Hb, Hemoglobin F is fetal Hb, Hb S is Sickle cell Hb, and there are several other types that have differing affinities for Oxygen.
- Abnormal Hemoglobins such as Sulfhemoglobin and Methemoglobin are not useful for O2 carriage.
What is oxygen carrying capacity of hemoglobin?
1.39 mL O2/g of Hb
Average Hb concentraiton in blood?
15 g/100 mL blood
What is O2 saturation?
Percentage of available sites that have O2 attached
Equation:
O__2 combined with Hb x 100
O2 capacity
- O2 sat pO2 of 100 = 97.5%
- O2 sat mixed venous with pO2 40= 75%
- O2 sat in blood with pO2 26.5= 50% (called P50)
What does arterial oxygen content include?
Amount carried in blood (both dissolved O2 and O2 bound to hemoglobin)
How do you calculate arterial o2 content?
CaO2= (Hb x SaO2 x 1.34mL O2/g of Hb) + (paO2 x 0.003 mL/mmHg/100mL blood)
(per 100mL)
How do you calculate Oxygen Delivery?
Do2= CaO2 x CO x 10 (per L)
It is easier to raise O2 by _____ than by oxygen adminitration
increased Hb
What are some properties of oxygen dissociation curve?
- Sigmoidal shape
- Up to P50, steep so large amount of O2 taken up by tissues for relatively small drop in alveolar/arterial po2
- Falt part at top, binding of O2 to Hb continues at low alveolar/arterial po2
- Shift to left= avid binding, less release
- Shift to right- less binding, easier release
What causes right shift?
Acidosis
Higher CO2
Higher temp
Higher 2-3 DPG
(CADET faces right)
What causes left shift?
Alkalosis
CO
Lower CO2
Lower temp
Lower 2-3 DPG
What is 2,3- DPG?
- Allosteric effector of Hb affinity for oxygen
- Binding decreases affinity promoting release
- Synthesis of 2,3 -DPG is controlle dyb local pH as normal glycolytic pathway
- High elevels of 2,3 DPG during pregnancy facilitate transfer of oxygen to fetal blood as fetal Hb is much less sensitive
Exercising msucle is acidic, hypercarbic and hot. _____ unloading of O2 by a shift to right
Increasing
2,3- DPG is ______ in face of chronic hypoxia, (such as high altitude, chronic lung disease)
Increased
This helps to shift curve to right and increase unloading of O2
CO binds ____ to Hb. This means it is _____ to bind to O2. This causes shift to _____ thus interfering with unloading of O2.
avidly; unavailable; left
What is impact of anemia and polycythemia?
In anemia, less hemoglobin to bind to O2 so O2 concentration in blood is decreaed, but it does not alter HBo2 saturation.
In polycythemia, theres an increase in Hb to bind, so increase in O2 concentration
CO2 is how many times more soluble than O2?
20x
How is CO2 carried in blood?
- Dissolved (like O2). CO2 is 20 times more soluble and
- 10% of CO2 is carried in blood
- Bicarbonate forms as
- CO2 +H2O –> H2CO3–> H + HCO3
- 60% CO2 carried as bicarb
- Carbamino
- compounds formed by combination of CO2 with amine groups in blood proteins
- 30% of CO2
CO2 dissociation curve is more ____ than O2 dissocation
linear
What is the haldane effect?
Presence of oxygenated Hb helps unload CO2 which can be breathed out.
