Chapter 6: Gas Transport by the blood Flashcards
What is the Henry law?
describes that the amount dissolved is proportional to the partial pressure
for every 1 mmHg PO2 there is 0.003mL O2/100 mL blood
What are the parts of hemoglobin?
4 x Heme - iron porphyrin compound
globin - made up of 4 polypeptide chains - 2 alpha and 2 beta chains
What is Hemoglobin A?
Normal adult hemoglobin
What is hemoglobin F and how does it differ from hemoglobin A?
fetal hemoglobin - has a higher affinity to oxygen
What is ferrous versus ferric iron? How do you call hemoglobin with ferric iron?
ferrous iron is the normal hemoglobin bound iron that is capable of binding, carrying, and releasing O2
ferrous becomes ferric iron when oxidized –> poor at binding and releasing O2
ferric iron hemoglobin form = methemoglobin
Fe2+ ferrous (there’s 2 of us)
Fe3+ ferric
What is the O2 capacity?
the maximum amount of O2 that can combine with Hb, i.e., when all Hb binding sites are occupied by O2
Explain relaxed (R) versus tense (T) forms of Hb. How does this affect the O2 dissociation curve?
relaxed Hb is oxygenated - once Hb binds to an O2 molecule, O2 affinity increases
tense Hb is deoxygenated - more difficult for O2 to bin
creates the sigmoid O2 dissociation curve –> less steep in the beggining then very steep, then flattens when O2 binding sites are saturated
What is the equation for the O2 concentration of arterial blood?
(Hb x SaO2 x 1.36) + (0.003 x PaO2)
Explain why the sighmoid shape of the O2 dissociation curve is physiologically beneficial
benefits of the flat upper portion:
* even if alveolar gas falls somewhat - loading of O2 won’t be affected (does not apply to large PAO2 drops)
* steep lower part means peripheral tissues can withdraw a lot of O2 from Hb with only a small drop in capillary PO2 –> maintains pressure gradient needed for diffusion of O2 into the tissue cells
What is the full name of 2,3-DPG?
2,3-Diphosphoglycerate
Name 4 changes that can shift the O2 dissociation curve to the right
- increase in H+ (i.e., lower pH)
- increase in temperature
- increase in CO2
- increase in 2,3-DPG
exercising muscle is acidic, hot, and produces more CO2 and benefits more from O2
What does a right shift of the O2 dissociation curve mean?
Hb offloads O2 easier, i.e., O2 affinity of Hb is reduced
What is the Bohr effect?
increased PCO2 will decrease the Hb affinity to O2 - i.e., Hb will offload O2 easier at the tissue capillaries
mostly attributed to the CO2 ability to increase H+ (decrease pH)
Where is 2,3-DPG produced?
in the RBC - end product of RBC metabolism
How does 2,3-DPG change in chronic hypoxia?
2,3-DPG will increase –> will assist the offloading of O2 in peripheral tissues