Gas transport Flashcards
Oxygen equilibrium curve - Hemoglobin
- relates PO2 of blood (how much available) to how much is bound to Hemoglobin
- s shaped (sigmoid) curve
- blood has both dissolved and bound O2
- curve is more sigmoid if there is a greater change in affinity
Oxygen equilibrium curve - myoglobin
- PO2 (free O2) decreases
- Affinity (ease of O2 access) increases
- hyperbolic curve
- P50 –> affinity (globin state)
Oxygen affinity
how easy is it for O2 to bind
- measured by P50 = PO2 when at 50% saturated (1/2 Mb has O2 bound)
Why is sigmoid curve important? (Hemoglobin)
helps unload oxygen into tissues at a high PO2
- creates a partial pressure gradient that drives diffusion into tissues
Allosteric
not active site for O2 attachment (bohr effect)
Bohr effect
shift of curve to the left in lungs (more sigmoid shape)
-CO2 enhances O2 delivery into tissues
- CO2 in tissues binds to hemoglobin & becomes more tense
- O2 affinity decreases, O2 unloads
- O2 diffuses into mitochondria
How does DPG (diphosphoglycerate) differ in affinity?
baby - low DPG, high affinity, left shifted curve
mother- high DPG, low affinity, right shifted curve
What does the height of curve mean in regards to affinity?
height of curve = oxygen carrying capacity (respiratory pigment in blood)
How do animals respond to low O2?
by altering respiratory pigment physiology
- increase concentration of respiratory pigment
- modify O2 binding properties of pigments (daphnia)
- alter preexisting pigments (fish decrease ATP & GTP within red blood cells after being placed in water low in O2
CO2 equilibrium curve
Haldane effect = O2 enhances CO2 unloading at the lungs + CO2 loading at the tissues
- acts as a buffer in the blood
-bound w/ O2 is a strong acid - hemoglobin (producing more H+)
- TISSUE = PO2 low, loading (higher affinity)
- LUNG = PO2 high, unloading (lower affinity)
