How does hemoglobin react to cigarette smoke in the lungs?

When you breathe in a lung-full of cigarette smoke, the carbon monoxide passes immediately into your blood, binding to the oxygen receptor sites and figuratively kicking the oxygen molecules out of your red blood cells. Hemoglobin that is bound to carbon monoxide is converted into carboxyhemoglobin, and is no longer able to transport oxygen. This means that less oxygen reaches a smoker's brain and other vital organs. Because of this added carbon monoxide load, a smoker's red cells are also less effective in removing carbon dioxide-a waste product-from his or her body's cells.