Flashcards in Transport of Gases (CO2, O2, dissociation curves) Deck (47)
________ is d\t or a function of oxygen tension (partial pressure).
What is P50 and what is the normal value for it?
The partial pressure of oxygen at which Hgb is 50% saturated with oxygen.
normal is 26-28mmhg
What SO2 corresponds to PO2's of 40 and 60mmHg?
remember 40, 50, 60= 70, 80, 90
What is the significance of the flat portion of the oxyHgb dissociation curve?
facilitates the unloading of oxygen by blood.... b\c in the flat portion of the curve, large changes in partial pressure of oxygen in arterial blood (PaO2) produce only small changes in oxygen saturation
What is the significance of the steep portion of the oxyHgb dissociation curve?
facilitates unloading of oxygen at tissues b\c large amounts of oxygen are unloaded from Hgb (large decrease in oxygen saturation) in response to small changes in the partial pressure of oxygen
Name the factors that cause a rightward shift in the oxyHgb dissociation curve. (using "RIGHTS")
Increased 2, 3, DP"G"
"H"ydrogen ions increased (decreased pH)
"S"ickle cell (HbS)
P50 ______ when there is a rightward shift.
P50 ______ when there is a leftward shift.
The ______ refers to the shift in oxyHgb dossociation curve in response to an increase or decreased PCO2.
*studied factors that shift the curve right or left. Bohr assessed how a change in CO2 shifts the curve.
Administration of opioids shifts the oxyHgb dissociation curve right or left?
Right--> produces resp depression, so CO2 accumulates and the curve shifts rightward
Name the comprehensive list of factors that cause a rightward shift in the oxyHgb dissociation curve.
- increased temp
- decreased pH (increased H+ concentration)
- increased PCO2
- increased 2, 3 DPG
- maternal Hgb
- sickle cell (HbS)
Name the comprehensive list of factors that cause a leftward shift in the oxyHgb dissociation curve.
- decreased temperature
- increased pH (decreased H+ concentration)
- decreased PCO2
- decreased 2, 3, DPG
- fetal Hgb (HbF)
A rightward shift facilitates _____.
A leftward shift facilitates ______.
Explain the normal process of the utility of the Bohr effect involved with the transport of gases (CO2 and O2).
blood travels through the capillaries in the systemic circuit, CO2 and acids diffuse into the blood from the tissue cells---> tissue metabolism causes an increase in temperature--> rightward shift--> O2 unloading is facilitated (for a given PO2, the blood holds less O2)
blood then diffuses through capillaries in the pulmonary circuit, CO2 then diffuses out of the blood to the alveoli--> curve shifts leftward, facilitating the loading of O2 (a given PO2, the blood holds more O2 when the oxyHgb curve shifts left)
Is oxygen release from hemoglobin to the tissues increased or decreased by acidosis?
increased; acidosis causes a rightward shift facilitating the unloading of O2 to the tissues--> increasing O2 delivery to the tissues
Total O2 carrying capacity of the blood is the sum of what two values?
hgb bound to O2 and dissolved Hgb
Who's law explains O2 dissolved in the blood?
dissolved oxygen= 0.003 x PO2
Most of the contribution to the O2 carrying capacity of the blood is from _______.
Hb bound O2
dissolved O2 only makes up a small portion
dissolved oxygen = ________ x ________
0.003 x PO2
How much oxygen is dissolved in arterial blood if PaO2 is 90mmHg?
dissolved O2: 0.003 x 90= 0.27
What is the difference in PO2 and PaO2?
nothing--> for the exam purpose
Calculate the increase in dissolved oxygen in the arterial blood if PaO2 increases from 50mmHg to 300mmHg.
50 x 0.003= 0.15
300 x 0.003= 0.9
the increase in dissolved O2 is 0.75mL O2/100mL blood
_______ liquids to dissolve gas, _______ liquids to dissolve solids.
What is 0.003 in the dissolved O2 equation?
O2 is carried in blood in two forms: ________ and _______
Hgb bound and dissolved
In a young, healthy individual, normal arterial blood (PaO2-100mmHg) has ______ mL O2/100mL blood dissolved and ______ mL O2/100mL blood bound to hemoglobin (98.5% SaO2; 15g Hg/100mL blood).
0.3mL dissolved; 19.8mL bound
What is the maximum oxygen carrying capacity of arterial blood in a young, healthy person breathing room air?
20.4mL; 20.1mL bound (100% saturation) and 0.3mL dissolved
Therapy with 100% O2 will produce much greater increases in oxygen content of blood if ________.
if the Hgb was poorly saturated prior to the admin of O2
-pulmonary disease (pulm edema, deadspacing)
-poor perfusion in relation to ventilation respond well
-pt with shunt (poor ventilation in relation to perfusion) are less responsive