Lec 9 Flashcards
Describe the transport of oxygen in the blood
It binds to hemoglobin and very slightly dissolves in plasma
How many polypeptide chains are there in a hemoglobin? What does it mean to be fully saturated?
there are 4, and fully saturated has 4 oxygens bound
What does the binding of O2 rate depend on?
- PO2
- temperature
- pH of blood
- P CO2
- BPG in blood (glucose product)
What is the O2-hemoglobin curve shape? What are the key values?
It is sigmoidal and has a slope from 10-50mm Hg and plateaus at 70-100mm Hg
What is the Hb saturation in blood leaving the lungs?
98%
What is the Hb saturation when the PO2 is less than 40 mmHg
Still 75%
What is venous reserve?
Only 25% of O2 is unloaded during the first pass, which means in exercise conditions there is still more O2 to be given
What happens to PO2 at high altitude? What effect does this have on saturation of Hb?
The PO2 goes up significantly, which makes for very small changes in hemoglobin saturation for changes in PO2
What produces BPGs? What do they do?
RBCs produce BPGs, which bind to Hb to reduce affinity for O2
What decreases hemoglobin affinity for O2?
increase in temp, PCo2, pH, BPG
What does low hemoglobin O2 affinity do to the blood?
It means the hemoglobin unloads more O2
Why does it make sense that CO2 decreases hB O2 affinity?
The Bohr effect states that H+ decreases affinity, which is a byproduct of the CO2 H2O rxn in blood
What are the 3 ways that CO2 is transported in the blood?
- Dissolved in plasma
- Bound to Hb (carbaminohemoglobin)
- bicarbonate ion in plasma
What is the Haldane effect?
HHb in tissues binds more CO2 than O2, which leads to blood taking more CO2 from tissues away
Where does the H2CO3 -> HCO3- + H+ happen?
In red blood cells containing carbonic anhydrase
Where does most CO2 get transported in the blood?
The bicarbonate ion in plasma
What is the chloride shift in RBCs?
Chloride goes into the cell to balance the diffusion of sodium bicarbonate to plasma
How is carbon dioxide moved from the blood to the alveola?
- CO2 dissolved in plasma moves out
- CO2 bound to Hb is released and moves out
- CO2 bicarbonate ion goes back into the RBC where it becomes CO2 and water again and moves out
What happens if blood is too acidic?
It is buffered by Hb or proteins
What happens if blood is too basic?
The bicarbonate ion diffuses into plasma
What does shallow rapid breathing do to blood pH?
Accumulation of CO2 in the blood leads to a basic pH
What does deep breathing do to blood pH?
Flushes out CO2, which leads to an acidic pH
What are the two brain areas responsible for respiration?
The ventral respiratory group and the dorsal respiratory group
What nerves innervate the dorsal respiratory group?
The phrenic and intercostal nerves
What is the VRG responsible for?
It is the pacesetting respiratory center and inspiratory center
What happens when VRG neurons fire?
Passive expiration
