lecture 27 Flashcards
the amount of gas in solution depends on solubility and partial pressures
- at equilibrium partial pressure in solution will be equal but concentrations are unlikely to be equal
- CO2 is 20x more soluble than O2 because it converted to and transported as HCO3-
O2 transport in the blood
- transported with hemoglobin which is found in the RBCs
- it has 4 subunits and each with contain a porphyrin ring and at the center of this ring is an iron atom which binds the oxygen molecule
- Hb has ability to bind 4 O2 molecules
total O2 in blood =
amount dissolved in plasma + amount bound to hemoglobin
red blood cells with hemoglobin are carrying ______ of their maximum load of oxygen
98%
what is the plateau portion of the O2-Hb dissociation curve
60-100 mm Hg
what propert of Hb leads to this sigmoidisity
- because of it is cooperative, the binding of O2 molecules increases binding affinity of remaining sites
if O2 binding lacked cooperativity what kind of graph would it be
hyperbolic
in the steep region
a small change in PO2 can result in a large change in % Hb saturation
what is P50
- P50 is the partial pressure of oxygen at which it hemoglobin is 50% saturated with O2
- 27 mm Hg
as p50 increases, hemoglobin’s affinity for oxygen _______
decreases
when PO2 levels are low the saturation of Hb with O2 ______ because ________
decreases because the affinity for O2 decreases
oxygen binding by Hb - effect of changing pH
- normal physiological pH = 7.4
- decrease in pH = 7.2
- increase in pH = 7.6
when pH decreases what happens
- it decreases hemoglobin affinity for oxygen therefore P50 increases
- Hb saturation curve shifts to the right and facilitates offloading of oxygen for working skeletal muscles that are producing lactate and need more oxygen
where in the body do we see a decrease in pH
we see a decrease in pH in skeletal muscle that are respiring and maybe building up things like lactate and protons that decrease pH
what happens to affinity of Hb for oxygen when we increase pH
- increasing pH will shifts Hb saturation curve to the left
- increasing pH will increase affinity of hemoglobin for oxygen and reduce offloading