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35 Cards in this Set

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What is the hemoglobinoxygen(Hb-O) dissociation curve?
The curve relating percentage saturation of the o2 carrying capacity of hemoglobin to the Po2.
How does the hemoglobin structure affect its o2 capacity?
Hemoglobin has a quarternary structure that varies in its affinty for o2 depending on the number of o2 bound to it.
how does the Hb-O dissociation curve affect the hemoglobin subunits in deoxygenated state?
hemoglobin subunits are in a tense configuration where they have a reduced affinity for O2.
How does the Hb-O dissociation curve affect the hemoglobin subunits when O2 is bound to it?
With each progressive O2 molecule, hemogllobin takes on a relaxed configuration where subsequent binding of o2 is facilitated as each O2 binding site is exposed(allosterism).
How does the sigmoid curve affect oxygen delivery at the:
Steep section
Plateau- High Po2 gives a large reserve during O2 loading.
Steep section- Small change in Po2 results in large changes in O2 saturation. This facilitates unloading of O2 at tissues.
Where is the plateau and the steep section of the sigmoid curve found in the human body?
Plateau- pulmonary capillaries
Steep section- Tissue capillaries.
What does decreased O2 affinity mean?
A higher Po2 is required for hemoglobin to bind a given amount of Oxygen.
What factors decrease the affinity of O2?
1. Low pH
2. Increased PCo2
3. Increased temperature
4. Increased 2, 3 diphosphoglycerate concentration.
What factors decrease the affinity of O2?
1. Low pH
2. Increased PCo2
3. Increased temperature
4. Increased 2, 3 diphosphoglycerate concentration.
What factors cause an increase in 2, 3-DPG concentration?
1. High pH
2. Thyroid hormone
3. Growth hormone
4. Androgens
5. High altitudes
What are the functions of Hemoglobin?
1. Facilitates oxygen transport
2. " Co2 transport
3. Acts as a buffer in the blood
4. Facilitates NO transport
What happens to the Hb-O dissociation curve with decreased affinity for o2 by hemoglobin?
Curve shifts to the right.
What does decreased oxygen affinity favor?
O2 delivery to tissue.
What is the Bohr effect?
Decrease in affinity of Hb for o2 due to lowered pH. This relates to the fact that deoxygenated Hb binds H+ ions more avidly than does oxygenated Hb.
Where is the Bohr effect used physiologically/
In the peripheral tissue(helps unload oxygen).
How does fetal Hb(Hbf) differ from adult hemoglobin(Hb-A)
HbF contains gamma polypeptide chains instead of beta chains.
What is the significance of the gamma chains versus the beta chains HbF?
There is a poor binding of 2, 3 DPG by the gamma chains causing HbF to have greater affinty for o2 than HbA.
How does anemia affect 2, 3 DPG concentration in RBCs?
Increases it.
How is myoglobin different from hemoglobin?
Myoglobin binds one rather than 4 molecules of o2 per molecule, resulting in a rectangular hyperbolar dissociation curve, typical of Michelis-mentin kinetics.
How does the dissociation curve of myoglobin affect its O2 uptake relative to hemoglobin?
because its curve is to the left of the Hb curve, it takes up o2 from hemoglobin in the blood and releases O2 only at low Po2 values.
Much of the myoglobin is found in the skeletal muscles. TRUE/FALSE
What does decreased arterial O2 content cause?
Decreased Hb concentration and reduced arterial O2 tension.
Which does Hb have more affinity for CO or O2?
CO(app 200 X greater affinity)
What is formed as a result of CO reacting with Hb?
How does carboxyHb formation affect o2 content?
1. decreases the functional Hb concentration
2. Reduces o2 carrying capacity of blood
3. Lowers tissue O2 tension.
How is Co2 transported in the blood?
H= buffered as HCO3- in plasma
2. Dissolved in plasma or in RBCs
3. Formation of carbamino-Hb in RBCs.
4. Formation of carbamino compounds with plasma protein.
Where does hydration of Co2 into HCO3- occur?
What enzyme catalyzes the conversion of Co2 into HCO3-?
Carbonic anhydrase catalyzes formation of H2CO3 from H2O and Co2, which dissociates into H+ and HCO3.
How does HCO3 enter the plasma?
Exchanged with Cl-(chloride shift)
Which two factors determine arterial or alveolar CO2 tensions?
Rate of Co2 production and alveolar ventilation.
Whatis the haldane effect?
Binding of O2 to Hb reduces its affinity for CO2.
Where is the haldane effect used physologically?
What is methmoglobin?
Hb that contains ferric(Fe3+) iron. It has a very high affinity for o2, resulting in decreased ability of Hb to unload O2.
How do obstructive diseases affect gas exchange?
Increases the time constant and results in a slower rate of acinar filling and emptying.
How do restrictive diseases affect gas exchange?
Reduce the time constant?