Oxygen and CO2 Transport II Flashcards
What is the P50 and what occurs to the Hb affinity curve when the P50 changes?
P50 increases - shifts curve to the right - unloading of oxygen
P50 decreases - shifts curve to the left - loading of oxygen
*P50 is the partial pressure of oxygen at which Hb is 50% saturated
What factors shift the O2 affinity curve to the right?
Lower pH (Increase in H+)
Higher temperature
Higher CO2
Increase in 2,3 - DPG
What factors shift the O2 affinity curve to the left?
Higher pH
Lower CO2
Lower Temperature
Lower 2,3-DPG
Fetal Hb
What conditions cause an increase in 2,3-DPG?
Persistant hypoxia -days to weeks
High Altitude
Chronic anemia
What does fetal Hb have a greater affinity for oxygen than adult Hb?
It doesn’t interact with 2,3 DPG
What is Polycythemia?
Increased RBC production (erythropoesis) in response to chronic hypoxia
Results in additional O2 carrying capacity and hematocrit
However also increases blood volume and viscosity, causing an increased workload on the heart
What three forms is CO2 carried in the blood?
Dissolved in plasma
Bicarbonate - comprises about 85% of transport
Bound to Hb - carbamino
What is the chloride shift (Hambruger Shift)?
As a product of the carbonic anhydrase reaction, HCO3 is transported out of the RBC
In order to maintain electoneutrality, Cl- from the blood is transported into the cell
Why is the change in H+ concentration minimized even though the carbonic anhydrase reaction is happening constantly?
Hb in the RBC buffers the H+ ion that is generated
Describe the effects of Hb oxygenation on CO2 affinity
DeoxyHb has a much higher affinity for CO2 than OxyHb
This allows for decreased affinity for CO2 in the lungs where PO2 is high, and consequently release of CO2
What is the relationship between CO2 content and PCO2?
Its a linear relationship and shows no saturation kinetics within the operating partial pressures of CO2
How do you find the new PCO2 after mixing two blood samples with different PCO2s?
Simply averaging the two because of the linear relationship between CO2 content and PCO2
How do you find the new PO2 after mixing two blood samples with different PO2s?
Average the O2 content of the two blood samples, then use this new O2 content to determine the PO2 of the mixture
What are the non-respiratory functions of the lungs?
Defense Mechanism
Air-Conditioning
Olfaction
Filtration and removal of particles
Blood Filter
Blood Reservoir
Metabolism of circulating substances
What is Immotile Cilia Syndrome?
Genetically transmitted disorder in which the cilia do not move normally
Patients are more susceptible to respiratory disease due to the increase of entry of foreign particles into the lung
