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Gas transport CJ
Gsa Transport by the blood
Question | Answer |
---|---|
Dissolved oxygen accounts for ___ml O2/100ml of blood | .3ml |
Dissolved oxygen supplies how many ml per minute of O2 | 90ml |
Hemoglobin accounts for ___ml O2/100ml of blood | 20.8ml |
The majority of O2 is found | Bound to hemoglobin |
Hemoglobin increases the amount of O2 in the blood for the same | Po2 |
Po2 in plasma is | 100 |
Function of hemoglobin | To increase the 02 in the blood at the same Po2 |
Explain why the plateu on the O2 dissociation curve is useful in the lungs | If the alveolar Po2 were to drop from 100 to 60, the saturation of hemoglobin would remain the same. This is good for storage of O2 in hemoglobin in the lungs |
Explain why the "steep region" on the O2 dissociation curve is useful in peripheral tissues | The Hb saturation drops dramatically for low Po2 values (such as in tissues) and the Hb releases the O2 to the tissue |
The Hb saturation curve is a measure of | Percent of Hb saturation, does not include dissolved oxygen or Hb levels |
The blood O2 content curve is a measure of | Total O2, both bound to Hb and dissolved |
In an anemic patient (decreased Hb) the Hb saturation curve would appear | Normal because the Hb is still saturated but there is just less Hb (so the percentage remains the same) |
In an anemic patient (decreased Hb) the total O2 content curve would appear | Vastly reduced |
In carbon monoxide poisoning, the Hb saturation curve will appear | Normal because CO binds readily to Hb, keeping the saturation percentage high |
In carbon monoxide poisoning, the Oxyhemogblobin level is | Extremely low because CO outcompetes O2 for Hb spots |
In CO poisoning, Po2 levels will appear | Normal |
A right shift in the HbO2 dissociation curve is know as the ___ effect | Bohr |
A right shift in the HbO2 dissociation curve is a result of | Lower Hb saturation for a given Po2, meaning Hb will give up oxygen more readily |
A left shift in the HbO2 dissociation curve is a result of | Higher Hb saturation for a given Po2, meaning Hb will hold on to oxygen more readily |
A left shift in the HbO2 dissociation curve is useful in what environment? | High altitude (because you have a lover Po2) |
A right shift in the HbO2 dissociation curve is useful in what circumstance? | Exercise because you want to be able to readily supply tissues with oxygen |
A left shift in the HbO2 dissociation curve can be caused by | Decreased H+, Decreased PCO2 and decreased red cell metabolism products |
What is P50 | Pressure of O2 when 50% of the Hb is saturated |
Normal P50 value | 27 mmHg |
P50 for a patient at high altitude would be | Lower than 27 mmHg |
P50 for a patient exercising would be | Greater than 27 mmHg |
P50 for a patient with Carbon Monoxide poisoning would be | Less than 27 mmHg |
Why is the O2 dissociation cure slightly right-shifted in venous blood? | Because venous blood contains more CO2 and is more acidic than arterial blood, leaving less room for O2 saturation |
What is the O2 saturation percent in arterial blood | 97.5% |
What is the O2 saturation percent in venous blood | 75% (due to increased CO2) |
What is the P02 in arterial blood | 100 mmHg |
What is the PO2 in venous blood | 40 mmHg |
Carbon dioxide is transported in the blood in three forms. They are | Bicarb (60%), Dissolved (10%) and Carbamino (30%- Co2+Hb) |
The HbCO dissociation curve has a __ saturation at a lower PO2 | Higher |
Carboxyhemoglobin does what to the PO2 | Nothing |
Carboxyhemoglobin has what effect on Hb saturation | None |
Carboxyhemoglobin has what effect on O2 content | Dramatically decreased |
Why are red blood cells the main facilitator of CO2 transport? (2 reasons) | RBC contain the enzyme carbonic anyhydrase that converts CO2 into bicarb for CO2 transport. In addition, RBC contain hemoglobin which is the main carbamino compound in the blood (for CO2 transport) |
How does the CO2 dissociation curve compare to the O2 dissociation curve? | The CO2 dissociation curve is more linear and steeper (no plateau) |
Explain the significance of the CO2 dissociation curve being more linear | This means that a very small change in PCO2 can result in large changes in the CO2 content in the blood. This small difference can unload a large amount of CO2 in the lungs |
What does the Haldane effect do in the lungs and periphery to O2 and Co2 | As blood unloads 02 in the periphery, it can take up lots of CO2. Conversely, in the lungs, oxygenation of the blood helps to unload the CO2 from the blood. |
Oxygenation in the lungs does what to CO2 | Unloads |
Deoxygenation in the tissues does what to CO2 | Loads |
Explain the Haldane effect | Deoxygenated Hb binds to CO2 to form carbamino compounds that "mop up" H+ ions produced in the conversion of CO2 to bicarb. This in turn facilitates the production of more bicarb. This facilitates more CO2 transport when O2 levels are low. |
Equation to determine blood pH from bicarb and CO2 concentrations | pH= 6.1+ log [HCO3-]/[CO2] |
Normal bicarb level in blood with pH level 7.4 | 24 mEq/L |
Normal CO2 level in blood with pH level 7.4 | 1.2 mmol/L |
Blood pH will be equal to 7.4 as long as the [HCO3-]:[CO2] is equal to | 20 |
Respiratory acidosis | Low pH, High PCO2 |
Respiratory alkalosis | High pH, Low PCO2 |
Metabolic acidosis | Low pH, Low Bicarb |
Metabolic alkalosis | High pH, high Bicarb |
Respiratory acidosis and alkalosis cause ___ compensation | Renal, Kidneys produce bicarb |
Compensation for Metabolic alkalosis is | Hypoventilation |
A full compensation for metabolic alkalosis would cause | Hypoxia |
Compensation for metabolic acidosis is | Hyperventilation |
Do you get a full compensation for metabolic alkalosis? | No |
Why does hyperventilation reduce arterial PCO2 but not help with the O2 content in the blood | Because O2 saturation is already at 100% but changes in CO2 produce more significant effects (think O2 dissociation curve v CO2 dissociation curve) |
Treatment for CO poisoning | Hyperbaric chamber to increase amount of dissolved O2 and to force CO off of Hb by increasing the competition with increase 02 |
How does carboxyhemoglobin affect the oxygen dissociation curve? | Shifts it to the left, higher saturation rate at lower PO2 levels causing the Hb to hold on to O2 more readily (BAD!) |
Normal Arterial O2 value | 21.1 ml O2/100 ml of blood |