Page 307 - Biology_F5

Biology for Advanced Level Secondary Schools

Most of the hydrogen carbonate ions reaction occurs and carbon dioxide is

formed in the red blood cells diffuse released (Figure 6.6).

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from the cytoplasm to the plasma and

combine with sodium to form sodium The dissociation of carbonic acid increases

hydrogen carbonate. The negatively the acidity of the blood. Hydrogen ions
charged hydrogen carbonate ions are lost (H ) then react with oxyhaemoglobin
+
from the blood cells, leaving them with to release bound oxygen and reduce the

a more positive charge. This is balanced acidity of the blood. This buffering action

by diffusion of chloride ions (Cl ) in the allows large quantities of carbonic acid
-

opposite direction, maintaining the balance to be carried in the blood without major

of negative and positive ions in either changes in blood pH.

side of the plasma and red blood cells.

This is called the chloride shift which

is also known as the Hamburger shift or

Hamburger phenomenon. It is named after This reversible reaction accounts for the
the founder, Hartog Jakob Hamburger. Bohr Effect. Carbon dioxide is a waste

The chloride shift reaction occurs in the product of respiration. Its concentration is

respiring cell. When the red blood cells high in the respiring cells; it is here where

reach the lungs, the reverse process or the haemoglobin releases oxygen.

CO + H O H CO H + HCO -
+
Tissue 2 2 2 3 3
CO 2 fluid CO + HHbNH HHbNHCOOH NaHCO

2
(Haemoglobin) 2 (carbamino-haemoglobin) 3
Plasma
HHb Na
+
O Tissue O + Hb +
2 fluid 2 Erythrocyte Cl-
HbO
2
(oxyhaemoglobin)
Chloride shift

Mitochondrion Red blood cell

Figure 6.6: Carbon dioxide transport by plasma and red blood cells

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