explain transport of gases through blood in humans ?
Transport of Gases − Oxygen and Carbon dioxide
Gases transported by blood
Oxygen − 97% through RBC
3% in plasma in dissolved state
Carbon dioxide − 20-25% through RBC
70% as bicarbonate
7% in plasma in dissolved state
Transport of Oxygen
Oxygen binds with haemoglobin to form oxyhaemoglobin.
1 molecule of haemoglobin carries 4 molecules of oxygen.
Formation of oxyhaemoglobin depends upon − pO2, pCO2, pH, temperature
In alveoli − pO2 (high), pCO2 (low), pH (high) temperature (low)
Hence, oxyhaemoglobin forms.
- In tissues − pO2 (low), pCO2 (high), pH (low) temperature (high)
- Hence, oxyhaemoglobin dissociates
Transport of Carbon Dioxide
CO2 is carried as carbamino-haemoglobin by blood.
When pCO2 (high), pO2 (low) − binding of CO2 occurs (as in tissues)
When pCO2 (low), pO2 (high) − dissociation of CO2 occurs (as in alveoli)
CO2 is bound with haemoglobin in tissue and dissociates in alveoli where it is released.
CO2 is transported as bicarbonate as well.
When pCO2 (high), forms (in tissues)
When pCO2 (low), CO2 + H2O forms (in Alveoli)
CO2 is trapped in tissue as and released in alveoli.
For 100 mL of deoxygenated blood, about 4 mL of CO2 is delivered to alveoli.