Hemoglobin

Hemobglobin (Hb) is the compound that enables red blood cells to carry oxygen. It also gives them their red color.

Each Hb molecule is made up of Heme, which is an iron-porphyrin compound, and globin, which is a protein.

Oxygen (O2) binds with great affinity to Hb, boosting the maximum O2 capacity of blood to about 20.8 mL O2/100 mL blood.

An important measure in medicine is O2 saturation, which tells you how much O2 is getting to a patient's tissues. The O2 saturation of Hb is calculated by:

The O2 saturation of normal arterial blood with PaO2 of 100 mmHg is about 97.5%. The O2 saturation of typical venous blood with PvO2 of 40 mmHg is about 75%.

the amount of O2 binding to Hb depends on the PO2 in a nonlinear fashion.

For more information on this, refer to the O2 dissociation curve.

Other important relationships to understand are the relationships between O2 binding and

• Temperature
• pH
• PCO2
• Carbon Monoxide

For more information on this topic, please refer to West , page 72.

West has all the necessary information on this topic. If time permits, this page will be further developed during the course of the section.

Also, check out the following links, which may be helpful:

• Hemoglobin and Cooperativity
• Hemoglobin and Oxygen Binding
• Hemoglobin Allostery
• (And for you die-hard engineers...) Hemoglobin Allostery