F7ii: Describe the movement of CO2 from cell to atmosphere
CO2 moves passively down concentration gradients
Cell
- Produced in mitochondria from aerobic metabolism
- 200mL/min at rest
Blood
- Diffuses from cells → blood
- ~120L of CO2 in body!
- Majority stored in bone matrix
- 3L is transported in blood:
- Dissolved gas
- HCO3–
- Carbamino compounds
- Transport bound to Hb facilitated by HALDANE EFFECT
“deoxygenated Hb can transport more CO2 cf. OxyHb”
Carriage in Blood
Arterial
Mixed Venous
V-A Difference
Carbamino
Arterial
0.0017mmol/L
Mixed Venous
0.002 mmol/L
V-A Difference
30%
Dissolved
Arterial
1.2 mmol/L
Mixed Venous
1.4 mmol/L
V-A Difference
10%
HCO3–
Arterial
24.4 mmol/L
Mixed Venous
26.2 mmol/L
V-A Difference
60%
PCO2
Arterial
40mmHg
Mixed Venous
45mmHg
V-A Difference
mL/dL
Arterial
48mL/dL
Mixed Venous
52mL/dL
V-A Difference
Atmosphere
- Negligible CO2 in atmosphere
- ∴Removed from alveolus by ventilation & expired into atmosphere