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23 Cards in this Set
- Front
- Back
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Oxygen is _______ soluble in blood.
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POORLY soluble.
Amount of dissolved O2 in blood is insufficient to support metabolic needs. |
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Each Hg molecule can bind ____ molecules of O2.
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4 molecs of O2
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Binding of O2 to Hg induces a __________, which allows for _____.
What is this known as? |
Conformational change, which makes it easier for other O2's to bind Hg
Known as COOPERATION |
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Oxyhemoglobin curve:
Left vs Right Shift |
Left shift: Hb has inc'd affinity for O2
Right shift: Hb has dec'd affinity for O2 |
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What is the Bohr effect?
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Lower pH-->Hg shifts Right (less likely bind O2; O2 more likely to dissociate from Hb)
So high pCO2-->low pH (keep this in mind) |
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How do lungs differ from exercising muscle in terms of Hb-O2 binding?
What differences account for this? |
Lungs:
High pO2, higher pH, favors Hg binding O2 Exercising muscle: Lower pO2 Higher pCO2 Lower pH! Higher TEMP! Favors O2 unbinding from Hb |
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Effect of 2,3-biphosphoglycerate on Hb affinity.
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Binds Hb with HIGH affinity, makes it less likely to bind O2.
RIGHT SHIFT Note: BPH is an intermediate product of glycolysis |
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Effect of storage time on Hb affinity for O2.
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BPG levels decline with length of storage.
Saturation of Hb with O2 increases, LEFT SHIFTS, and is less likely to release O2 in patient. |
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What is DO2?
Equation? Normal value? |
O2 supply delivered to tissues per minute
DO2 = CO x Arterial O2 Content Nl value ~1000 L O2/min |
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Equation for O2 consumption?
Normal value? |
O2 consumption = CO x (Arterial O2 - Mixed Venous O2)
~240 mlO2/min |
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How does O2 delivery change with age? Why?
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Resting O2 delivery declines with age to age-related declines in Hb (and resting CO)
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How does maximal capacity for O2 change with age? Why?
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Maximal capacity declines with age.
Due to: Dec'd max attainable HR and hence CO Also, age-related Hb [ ] decline |
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Structural components of HbA and HbF.
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HbA: 2 alpha-, 2beta-chains
HbF (FETAL): 2 gamma-, 2 alpha-chains; allows for a LEFT SHIFT (higher affinity for O2; helps get O2 from mom into fetus) |
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Methemoglobin:
General Effect on Hb affinity Causes |
Hb can bind O2 if heme iron is in ferrous form (Fe2+)
If oxidized to ferric Hg (Fe3+) like in methemoglobin, cannot bind O2. Can't bind O2, less effective in terms of O2 delivery, and left shifts all other Hb molecules on RBC. Causes: Inherited deficiencies of methemoglobin reductase, inherited abnl Hbs, oxidant stress from drugs/toxins (amyl nitrite), NITRITE containing drugs |
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Clinical usefulness of methemoglobin.
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Avidly binds cyanide in cyanide poisoning!
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The reaction of Hb with CO produces ________.
Effects of this? |
Hb + CO --> Carboxyhemoglobin
CO competes competitively with O2 for Hb, decreasing total O2 capacity of blood. ALSO stabilizes relaxed form of Hb, causing LEFT-SHIFT. |
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HbS contains 2 mutant ________ chains, and undergoes reversible ___________.
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HbS has 2 mutant beta-chains
HbS can undergo reversible polymerization, which distorts shape of RBC into sickle-shape. |
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Where is pCO2 the highest?
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In mitochondria, which produce CO2. Difuses through cells to blood down partial pressure gradient
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CO2 vs O2:
Transport in Blood |
CO2:
In solution in plasma in small amount (similar to O2) Most transported as Bicarb ion, which requires CARBONIC ANHYDRASE (abundant in RBCs, not in plasma) Carbaminohemoglobin--doesn't bind to Fe of heme group, binds amino group in globin chain |
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What is the Bohr effect?
Explain when chloride shift plays a role. |
At tissue level, CO2 produced. Once diffuses into blood, enters RBC, forms carbonic acid, dissociates into H+ ions and bicarb (or binds Hb)
H+ ions formed bind Hb and favor O2 dissociation at tissue level. If too much HCO3- builds up, won' thave dissociation of CO2 + H2O into ions, so Cl- is exchanged in the cell for HCO3-. Known as Chloride Shift. |
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What is the Haldane effect?
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At any given pCO2, more CO2 can be carried by de-O2 blood than in O2 blood, bc:
Deoxy'd Hb is more effective at binding CO2 Deoxyhemoglobin buffers H+ favoring carbonic acid dissocn and further bicarb formation (more CO2 carriage in blood as bicarbonate) |
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What is the effect of oxygen on blood CO2 content curve?
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Causes RIGHT shift
Again, an example of the Haldane effect. |
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The lung environment has ____ pO2 and a _____ pCO2, which allows for ______.
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Lung environment has high pO2, low pCO2. Allows for CO2 unloading.
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