Definition: When we breathe, our lungs take in oxygen that goes into our blood. Sometimes the body has trouble getting enough oxygen to its cells, either due to a lung or a heart problem. This causes cyanosis -- when the skin, inside of the mouth, lips, or fingernails turn a bluish color. Somtimes cyanosis makes the skin in light-skinned people look dusky, or blue-gray.
Children who are born with certain types of heart defects, such as Tetralogy of Fallot, may have cyanosis when they cry, are upset, or are very active.
Pronunciation: sye-a-NO-sis
