smoking hardens your arteries. This prevents them from being elastic like normal and being able to stretch and expand. Therefore if you have cholesterol buildup on the inside of an artery the artery is no longer able to expand and let the blood cells flow around the build up. In some cases the force of the blood backing up forces the cholesterol to break loose and the clump ends up lodging in an artery in your heart because they are so tiny which blocks the blood flow to an area of the heart and causes a myocardial infarction. Smoking also increases the levels of carbon monoxide in your blood and carbon dioxide in your tissues. the blood cells supply oxygen to your tissues but because of the smoke and carbon monoxide the cells are unable to pick up the carbon dioxide that is left after your body uses the oxygen which causes poor circulation to the affected areas.