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19 Cards in this Set
- Front
- Back
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Formula for concentration of O2 in blood?
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[O2]= Partial pressure of O2 x Solubility of O2
(if you solve this, you will find that O2 is poorly soluble in the blood. Thus, dissolved O2 in the blood is a small player in the metabolic needs of the body-- mainly Hb bound O2!) |
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What is the structure of Hb?
One molecule of Hb can bind ___ number of O2 molecules. |
Structure: 4 globins, each containing an Fe2+ group. Fe2+ binds oxygen.
4 O2 can be bound by one Oxyhemoglobin. |
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What is the shape of the Oxygen binding curve for Hb? Why?
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Sigmoidal shape due to cooperative binding (binding of O2 by hemoglobin results in conformational change that makes subsequent binding easier).
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Shifting the Hb curve to the Left results in _____ [↑,↓] O2 affinity.
Shifting the Hb curve to the Right results in _____ [↑,↓] O2 affinity. |
Shifting curve to the left results in INCREASED O2 affinity.
Shifting curve to teh right results in DECREASED O2 affinity. *y axis: percent O2 saturation, x axis: oxygen partial pressure |
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What factors cause a Right shift in the oxygen binding curve of Hb?
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"CADET, face right!"
CO2, Acid environment, 2,3, DPG, Exercise, Temp (↑) |
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What is the Bohr effect?
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The effect of pH on Hb affinity for oxygen.
Alkaline = left shift ↑pH (i.e.↓ H+) =↓ CO2 = ↑ O2 affinity Acid = right shift ↓pH (i.e. ↑H+) = ↑CO2 = ↓O2 affinity (more O2 unloading) |
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What is 2,3, DPG?
Is stored blood a less effective transporter of O2? why or why not? |
2,3, DPG= intermediate product of glycolysis in RBCs. It binds to and stabilizes deoxyHb (so decreases affinity of O2 for Hb --> right shift).
Blood in blood bank has DECREASED DPG, so blood will have higher affinity for Hg (less potential for O2 to be delivered). Stored blood is, thus, LESS EFFECTIVE at transport of O2. |
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Formula for O2 delivery (DO2)
Formula for arterial O2 content |
O2 Delivery = CO x arterial O2 content
Arterial O2 content= PPO2 x solubility of O2 in blood + Hb x Hb saturation x 1.34 mlO2/g Hb |
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What are the three most important factors in O2 delivery?
What are the most important determinants of Blood O2? |
1. Hb **
2. O2 saturation of Hb ** 3. CO **= most important determinants of blood O2 |
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How can you measure O2 consumption?
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O2 consumption = CO x A-V O2 difference (Fick principle)
measure CO measure arterial O2 - venous O2 (by taking blood from aorta and pulm artery) |
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Hb in mixed venous blood is normally _____% saturated with oxygen.
How does O2 delivery differ in the elderly? |
nl mixed venous blood = 70-75% sat with Hb
In elderly: 1. Hb declines with age 2. Decreased maximal HR (so ↓ CO) - both contribute to decreased O2 delivery |
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Structure of HbA vs. HbF?
Oxygen affinity of HbA vs. HbF? P50 of HbA vs. HbF? |
HbA= 2 alpha, 2 beta
HbF= 2 alpha, 2 gamma Hb A= decreased O2 affinity (right shift) HbF= increased O2 affinity (left shift) P50 (partial pressure of O2 at which Hb is 50% saturated) HbA P50 > HbF P50 |
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What is Methemoglobin?
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Hb that has undergone oxidation (ferrous --> ferric iron). This decreases the O2 binding capacity for the molecule.
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What is the most common etiology for methemoglobinemia? How do people present.
What is the cure? |
Methemoglobinemia- cyanosis.
- Mostly Iatrogenic (amyl nitrite, local anesthetics, Cyanide treatment since MetHb avidly binds cyanide) - Can also be inherited defects (ex: MetHb reductase defect) Rx= Methemoglobin reductase, or methylene blue (reverses oxidation of iron so it can bind O2) |
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What is the effect of CO on the oxygen binding Hb curve? Why?
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Left shift of curve
CO competitively binds Hb and latches on, preventing O2 from binding. It also left shifts the curve causing increased O2 affinity when O2 is present (prevents O2 unloading to tissues) |
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Structure of Hb in patients with Sickel cell disease?
Why is it problematic? |
HbS: 2 alpha chains, 2 MUTANT betas (βs)
Single amino acid substitution (V-->E at 6 position) In low O2 envrionements, HbS undergoes polymerization (forms rouleauxs)- can cause hemolysis & vascular occlusion --> anemia |
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Where in the body is the PCO2 highest?
CO2 is carried in the blood in what three forms? |
PCO2 highest in mitochondria (where it's produced after aerobic metabolism)
1. Dissolved CO2 (small amount) 2. HCO3- (bicarb) 3. Carbaminohemoglobin HbCO2 |
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What is HbCO2?
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Carbaminohemoglobin
CO2 does NOT react with Fe2+ groups (it binds at amino terminal of the molecule). The process generates H+. |
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Would you see more CO2 in deoxygenated or oxygenated blood? Explain.
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DEoxygenated blood
1. Deox Hb is more effective at binding Co2 2. Deoxy Hb buffers H+ (favors further HCO3 formation, more CO2 in blood) *this is called the HALDANE Effect |
