1. Calculate partial pressure of O 2 at Sea level Nitrogen78.08% Oxygen20.95% Water Vapor0 to 4 % Argon0.93% Carbon Dioxide0.036% Neon0.0018% Helium0.0005% Methane0.00017% Hydrogen0.00005% Nitrous Oxide0.00003% Ozone0.00004% What’s in our air? P gas a = Gas a X P total Gas mix

2. The respiratory pigments… Why are they important? 100X increase!

3. O 2 -Hb dissociation curves: Describe activity of Hb at different P O 2 % saturation PO2PO2

4. O 2 -Hb dissociation curves: P 50 is a measure of O 2 affinity Hb with a high affinity has a lower P 50 Animals that have Hb with high affinity: Hb is saturated when O 2 concentrations are relatively low b/c Hb will not release O 2 unless O 2 levels are very low this kind of Hb favors O 2 uptake (loading) Hb with a low affinity has a higher P 50 Animals that have Hb with low affinity: Hb is only saturated when O 2 concentrations are relatively high b/c Hb is more likely to “let go” of O 2, even if O 2 levels are pretty high this kind of Hb favors O 2 delivery (offloading) HIGH AFFINITY LOW AFFINITY

5. Comparing dissociation curves… myoglobin P 50 % saturation P O 2 (mmHg) hemoglobin 0 20 40 60 80 100 306090

6. Weddell Seal Harbor seal Human

7. Comparing Total O 2 Stores: