1. External and Internal Respiration

2. Learning Outcomes: Analyse internal and external respiration
State location
Describe conditions (ph, temperature)
Describe roles of oxyhemoglobin, carbaminohemoglobin, reduced hemoglobin, bicarbonate ions, carbonic anydrase
Write Chemical equations for external and internal respiration

3. 4 Levels of respiration Breathing External respiration- in the lungs
(what gas exchange occurs here?)
Internal respiration - in the tissues
Cellular respiration - in the mitochondria of cells (what is used and produced?)

4. Fig. 15.8

5. Fig. 15.4

9. Fig

10. 1. External (lungs): O2
O2 diffuses from the alveoli into the blood (why?)
What molecule in the blood does O2 bind to?
O2 binds to hemoglobin to form oxyhemoglobin
Hb + O HbO2

11. Binding of O2 to hemoglobin occurs best at lower temperature, higher pH and higher PO2 (oxygen pressure) of the lungs

12. Fig. 15.9

13. 2. Internal (tissues): O2
O2 dissociates from Hb, leaving deoxyhemoglobin
HbO Hb + O2
Bond is weaker due to higher temperature, lower pH and lower PO2
O2 diffuses into tissue fluid and cells, where it is used for cellular respiration

14. 3. Internal (tissues): CO2
What process produces CO2?
CO2 is produced by cellular respiration in all cells
CO2 diffuses out of cells into tissue fluid, and then into capillaries
A small amount combines with Hb to form carbaminohemoglobin
Hb + CO Hb CO2

15. Most CO2 combines with H2O to form carbonic acid, which dissociates to form hydrogen ions and bicarbonate ions:
CO2 + H2O H2CO H+ + HCO3-
This reaction is catalyzed by the enzyme carbonic anhydrase (found in red blood cells)

16. HCO3- is carried in the plasma
H+ is picked up by hemoglobin, forming reduced hemoglobin:
H+ + Hb HHb
This prevents too much acidity in the blood

17. 4. External (lungs): CO2 Bicarbonate ions release CO2 :
H+ + HCO H2CO H2O + CO2
Carbaminohemoglobin releases CO2
CO2 diffuses out of the capillaries into the alveoli, to be breathed out