Resp. 4 - Gas transport Flashcards
The only true measure of O2 in our blood is
dissolved O2 in blood plasma and the oxygen bound to hemoglobin
O2 Transport in Blood
- Dissolved (~2%)
2. Bound to Hemoglobin (~98%)
• As PO2 changes, so does
saturated hemoglobin%.
What factories effect PO2 saturation
• Temp, Ph, and PCO2 also all effects % of saturated hemoglobin
O2 Transport in Blood- Dissolved
Content of arterial [O2] dissolved (ml O2/ dl blood) = 0.3 ml O2 / do blood
O2 Transport in Blood- Hemoglobin
Content of arterial [O2] Hb (ml O 2/ dl blood) = 20 ml/dl
• [O2]arterial =
- [O2]arterial = dissolved + Hb
- = 0.3 ml/dl + 20 ml/dl
- = 20.3 ml/dl
Venous O2 Content
- [O2 ]venous = 1.35 x 15 x 75%
* [O2]venous = ~15 ml/dl
Hemoglobin Saturation in Hb-O2 Dissociation Curve:
- From the hemoglobin dissociation curve:
Oxygen capacity
N
Hemoglobin saturation →
The percentage of the available hemoglobin binding sites that have the oxygen attached.
• At the level of the arterial blood where PO2 is 100 mmHg, hemoglobin saturation is about 97.5%
Oxygen capacity →
the maximum amount of oxygen that can be combined with hemoglobin
- Depends on how much hemoglobin is present in the blood; a change in the amount of hemoglobin will change the oxygen capacity
- At the level of the arterial blood where PO2 is 100 mmHg, hemoglobin, saturation is about
97.5%
- At the level of the mixed venous blood were PO2 is about 40 mmHg, hemoglobin saturation is about
75%
At a higher temp, hemoglobin carries
more Oxygen bound to its self
At a lower temp, hemoglobin carries
Less oxygen bound to itself, but more O2 is in the tissue.
creating a solution that’s acididoc, high in
CO2 (61) and lower pH. With 50% saturation, more O2 is free to dissociate and diffuse into tissue
creating a more basic solution, there’s
more O bound, so less to diffuse into the tissue where you need it.
CO 2 Transport in Blood
- Dissolved (10%)
- Carbamino Hemoglobin (20%)
- Bicarbonate (70%)
Bicarbonate rxn
CO2 + H2O —> H2CO3 —-> H+ + HCO3-
Rxn catalyst: carbonic anhydrase
Rain is reversible
What percent of CO2 coming in form the tissue, going into the plasma does what
- 11% dissolves into plasma
- 89% goes into the RBC
Of the 11% of CO2 entering the plasma, what happened to the 11%.
- 6% dissolves in plasma
- <1% reacts with R-NH2 = H+
- 5% forms bicarbonate + H+ (slow rxn)
What happens to that 89% of CO2 entering the RBC ?
- 4% dissolved
- 64% form bicarbonate and H+ (with carbonic anhydrase)
- 21% forms carbon hemoglobin and H+
How does the CO2 form bicarbonate in the RBC, and what happens to it?
CO2 reacts with OH- that comes form dislocated H2O entering the RBC, bicarbonate then it exchanged with Cl- ions (electro neutral)
Chloride (hamburger) shift
The bicarbonate produced in the RBC is then exchanged for Cl- ions through a transporter because this facilitated the uptake of CO2.
Of that 21% of CO2 forming carbon hemoglobin and H+, what happens to the H+
The H+ binds to the Hb instead of the Hb binding to the O2, therfore allowing the O2 to diffuse into the tissue where its needed (Haldane effect)
Haldane effect
Hb bound to H+ makes O2 available to diffuse into the Periphery, so Hb has a higher affinity for H+, causing a disassociation of O2 bound to Hb and to make it available to diffuse into tissues where you need it (dissolves into plasma first, then goes into tissues).
The 3 purposes H+ has by binding to Hb
- Hb bound to H+ makes O2 available to diffuse into the Periphery, causing a disassociation of O2 bound to Hb and to make it available to diffuse into tissues where you need it.
- important for acid base balance. Free H+ makes pH stable. Hb acts as BUFFER
- Hb high affinity for H+ facilitates CO2 uptake, cuz ur reducing one of the producing, increasing I demand for CO2
What does an increase in alveolar ventilation do in terms of CO2?
Removes / decreases CO2
Increasing ventilation removes CO2 by
exhaling into the environment, reversing the rxn direction into using up H+ to product CO2, so you compensate for being acidionc by increasing the pH.
When is an increase in alveolar ventilation used in terms of Ph?
If the pH is to low (acidic) then an increase in ventilation will DEC CO2 = use more H+ to balance rxn, making less acidic
When is a decrease in alveolar ventilation done in terms of CO2 ?
To increase of add CO2
Having to much alkaline in the blood, you reduce
ventilation = adding CO2 = making more H+ (acidic)
When is a decrease in alveolar ventilation done in terms of pH ?
If pH is too high, to basic, DEC ventilation to INC CO2 = uses more CO2 to produce MORE H+ to drop pH and make more acidic
