FILL IN EVALUATION FORM

BUFFERING EFFECT OF HAEMOGLOBIN

• Hydrogen ions produced in the red blood cell from the dissociation of carbonic acid are buffered primarily by haemoglobin.

H+	+	Hb-		HHb

• Plasma proteins are effective buffers (but to a lesser extent than haemoglobin), due to their free carboxyl and free amino groups that dissociate.

RCOOH		RCOO-	+	H+
RNH3+		RNH2	+	H+

• Haemoglobin is a powerful acid-base buffer as in addition to the free carboxyl and free amino groups, haemoglobin also contains 38 histidine residues that also dissociate. Haemoglobin has six times the buffering capacity of plasma proteins due to the presence of the histidine residues.

• Haemoglobin is therefore important in maintaining the acid-base balance of the blood as well as transporting oxygen.

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