Haemoglobin – The substance in the red blood cells that transports oxygen and carbon dioxide

(Pronounced hee-muh-glow-bin)

To remember what haemoglobin means use the following mnemonic:

He must travel the globe in (haemoglobin) a red blood cell transporting an ox (oxygen) and a car (carbon dioxide).

Haemoglobin is a protein found in red blood cells that carries oxygen from the lungs to the body's tissues and returns carbon dioxide to the lungs. It is made up of four protein subunits, each containing an iron-carrying molecule called heme that binds to and transports a single molecule of oxygen, therefore each haemoglobin molecule can bind up to four oxygen molecules or four carbon dioxide molecules. 

Levels of haemoglobin in the blood can be measured to diagnose a variety of conditions, such as anemia and dehydration.