Chapter 29, Problem 29.47AP

Interpretation Introduction

Interpretation:

The partial pressure of ${\text{O}}_{\text{2}}$ at which hemoglobin is $\text{50}\text{\%}$ saturated with oxygen and the percentage saturation of hemoglobin at $21\text{\%}$ oxygen has to be identified.

Concept introduction:

Hemoglobin:

• Composed of four polypeptide chain with a quaternary structure.
• A central heme molecule is there in each protein chain and each of the four hemes can bind with one ${\text{O}}_{\text{2}}$ molecule.
• Each heme molecule in its centre has ${\text{Fe}}^{\text{+2}}$
• The bright red haemoglobin with four oxygens is called oxy haemoglobin.
• The dark red-purple haemoglobin in which one or more oxygen is lost is called deoxyhaemoglobin.

Hemoglobin can bind four oxygen molecules; one at each of its four heme groups, cooperatively as first $O_2$ bind at one heme increases the oxygen affinity of the remaining heme groups in the same hemoglobin molecule.

The degree of saturation of hemoglobin is the percentage of heme units bound to oxygen at a given moment.

The binding of $O_2$ to hemoglobin depends on the $p{O}_2(partialpressureofoxygen)$ in the blood and the bonding strength, or affinity between oxygen and hemoglobin.

Oxygen diffuses out of the arterial ends of tissue capillaries and carbon dioxide out of the tissue because of difference in partial pressure.