Term
| How is oxygen transported in the blood? |
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Definition
dissolved in plasma (2%)
bound to Hg in erythrocytes (98%) |
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Term
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Definition
| 2 alpha and 2 beta subunits each with a heme group, which can bind 1 O2 molecule. Each Hg molecule can carry 4 O2 molecules |
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Term
| What role does globin play in Hg? |
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Definition
| prevents O2 from binding permanently to the iron atom of Hg, allowing for O2 uptake & release as needed |
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Term
| ____ enzymes are involved in the synthesis of heme from iron an _____ |
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Definition
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Term
| Why does O2 bind more readily to hemeoglobin after 1 molecule has already bound? |
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Definition
| the binding of the first O2 induces a conformational change that 'encourages' more O2 to bind. the reverse happens when it's time to release the O2 |
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Term
True or False
Heomglobin's affinity for O2 is linear |
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Definition
false
saturation/affinity for oxygen increases a PaO2 in the tissues increases |
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Term
| What factors affect oxygen transport by Hg? (4) |
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Definition
PO2
temperature (as temp rises, affinity falls
PCO2 & pH
organic phosphates |
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Term
| How does PCO2 affect Hg's affinity for O2? |
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Definition
high CO2 = low pH (more acidic)
lower pH = less affinity for oxygen |
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Term
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Definition
| oxyhemoglobin dissociation curve shifts to the right in response to a drop in pH arising from CO2 accumulation |
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Term
| How do organic phosphates affect Hg's affinity for O2? |
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Definition
DPG is present in RBCs at the same levels as Hg.
-DPG inhibits O2 from binding
-if oxygen levels are low, DPG levels increase shifting the dissociation curve right and promoting the release of O2 from hemoglobin into tissues |
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Term
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Definition
| reddish blue colour of hemoglobin due to oxygen depletion |
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Term
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Definition
| measuring the difference between oxy-Hb and deoxy-Hb to calculate the % of Hb that is oxygenated |
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Term
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Definition
| uncreased unloading of O2 in tissues due to the low pH created by production of CO2, carbonic acid & lactic acid |
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Term
| Why is CO poisoning a thing? |
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Definition
| CO competes with O2 for binding sites on Hb, and has 4x the affinity |
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Term
| What is the Haldane effect? |
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Definition
increased ability of blood to carry CO2 resulting from deoxygenation of the blood
-removal of O2 from Hb increases Hb's affinity for CO2 |
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Term
| Which is greater, PCO2 of tissue or of blood? Why is this important? |
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Definition
tissue
-CO2 will move down concentration gradient into the blood for removal |
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Term
| How is CO2 transported in the blood? |
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Definition
-converted to bicarbonate ions & diffuses into plasma
-bound to hemoglobin
-dissolved in plasma as CO2 |
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Term
| What are the fetal adaptations to low oxygen tensions? |
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Definition
-higher affinity of Hb for oxygen
-higher Hg concentration
-higher cardiac output |
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Term
| Why do fetus (fetusi? fetuses?) need adaptations for fetal circulation? |
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Definition
| the umbilical vein has lower oxygen tension |
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