Since we are talking about pulmonary decriulation, I presume that the waste is CO2.
CO2 is transported dissolved in plasma (7 to 10%), in the form of carbhemoglobin (20 to 30%) and in the form of bicarbonates (HCO3-) (60 to 70%) of the tissues to the pulmonary circulation.
The cells produce about 200 ml / min of CO2 and the lungs expel the same amount.
The binding of CO2 to Hb is rapid and reversible. Since the binding site consists of amino acids that are not part of the heme, this bond does not compete with that of O2. The association of carbhemoglobin is influenced by the partial pressure of CO2 and the degree of saturation of hemoglobin in oxygen. The influence of O2 saturation is called the Haldane effect: deoxyhemoglobin has a high affinity for CO2 and H + ions. Thus, at the tissue level, the arrival in the circulation of CO2 lowers the pH, which promotes the dissociation of oxyhemoglobin (Bohr effect); the affinity of hemoglobin for CO2 then increases rapidly because of the Haldane effect. In the lungs, the mechanisms are reversed.
The CO2 in solution forms carbonic acid which dissociates into bicarbonate and H + ions.
