Your vascular system is made up of vessels that carry your blood throughout your body. Arteries carry oxygen-rich blood away from your heart. Veins carry oxygen-poor blood back to your heart. Your blood leaves the left side of the heart and is pumped out to the rest of your body.
The main artery from your heart is called the aorta. As your blood travels throughout your body, it enters smaller and smaller blood vessels, reaching every cell, dropping off nutrients and picking up waste products and carbon dioxide.
Your blood then starts the trip back in your veins, entering larger and larger ones as it goes, passing through your kidneys and liver on the way to drop off waste products. The blood eventually arrives back at the right side of your heart to start the trip all over again.
As we age, our arteries tend to thicken, get stiffer, and narrow. This is called arteriosclerosis. A form of arteriosclerosis is atherosclerosis, which is the build-up of plaque and cholesterol in large and medium-sized arteries. A narrowing of the arteries from the build-up of plaque can lead to coronary heart disease, and can cause a heart attack when this occurs in the blood vessels leading to the heart.
The same situation in the arteries leading to the brain can cause strokes. Narrowing of the arteries in other places, such as your legs, can cause what is called Peripheral Arterial Disease, or PAD. PAD can lead to sores, pain with walking, or amputation. When the smaller arteries are affected it is called arteriolosclerosis.