An artery is a blood vessel that carries blood away from your heart to the rest of your body. Most arteries transport oxygen-rich blood, delivering it to your organs, muscles, and tissues so they can function. Your arterial system operates under high pressure, essentially acting as the distribution network that keeps every cell in your body supplied with what it needs to survive.
How Arteries Are Built
Arterial walls have three distinct layers, each with a specific job. The innermost layer, called the intima, is a single sheet of smooth cells that directly contacts your blood as it flows through. This lining is incredibly thin, but it plays an outsized role: it helps regulate blood flow, prevents clotting, and serves as the first barrier between your blood and the vessel wall. Beneath these cells sits a supportive mesh of proteins and fibers.
The middle layer is the thickest part of an arterial wall. It contains rings of smooth muscle and elastic fibers that allow the artery to expand and contract with each heartbeat. This is what gives arteries their ability to handle the force of blood being pumped directly from the heart. When your heart contracts, arterial walls stretch to absorb the pressure surge, then recoil to keep blood moving forward between beats.
The outermost layer is made primarily of collagen, a tough structural protein. It anchors the artery to surrounding tissues and prevents the vessel from over-expanding. This layer also contains tiny blood vessels that supply the arterial wall itself with nutrients, since the wall is too thick to be nourished by the blood flowing through its center alone.
What Arteries Actually Do
Every time your heart beats, it pushes blood into the aorta, the largest artery in your body. From there, blood branches into progressively smaller arteries that reach every region of your body. These vessels don’t just act as passive tubes. The muscular walls of your arteries actively tighten or relax to regulate how much blood reaches different areas. During exercise, for example, arteries supplying your muscles widen to deliver more oxygen, while arteries to less active areas narrow.
This pressure-driven system is what you measure when you check your blood pressure. A normal reading is less than 120/80 mmHg, according to the American Heart Association. The top number reflects the pressure inside your arteries when your heart contracts, and the bottom number reflects the pressure when your heart relaxes between beats.
Types of Arteries
Not all arteries are the same. The largest ones, like the aorta and the arteries leading to your lungs, are called elastic arteries. Their walls contain a high proportion of stretchy fibers, allowing them to absorb the powerful surges of blood coming directly from the heart. Think of them as shock absorbers that smooth out the pulsing flow into something more continuous.
Medium-sized muscular arteries branch off from these larger vessels and direct blood to specific organs and regions. They have proportionally more muscle in their walls, which gives your body fine control over where blood goes. The arteries supplying your kidneys, your intestines, and your limbs fall into this category.
The smallest arteries are called arterioles. These tiny vessels connect the muscular arteries to capillaries, the microscopic vessels where oxygen and nutrients actually pass into your tissues. Arterioles are the main site where your body controls blood pressure on a moment-to-moment basis, widening and narrowing in response to signals from your nervous system and hormones.
The Pulmonary Artery Exception
There is one major exception to the rule that arteries carry oxygen-rich blood. Your pulmonary arteries carry oxygen-poor blood from the right side of your heart to your lungs. There, the blood picks up fresh oxygen and releases carbon dioxide, a waste product. The blood then returns to the left side of your heart through the pulmonary veins before being pumped out to the rest of your body through the aorta. So the defining feature of an artery isn’t the oxygen content of its blood. It’s the direction of flow: arteries always carry blood away from the heart.
How Arteries Differ From Veins
Arteries and veins are built for different jobs. Arteries handle high-pressure blood flowing away from the heart, so they have thick, muscular, elastic walls. Veins carry blood back to the heart under much lower pressure, so their walls are thinner and less elastic. Veins also contain one-way valves that prevent blood from flowing backward, something arteries don’t need because the heart’s pumping force keeps arterial blood moving in one direction.
If you were to cut across an artery and a vein of the same size, the artery would have a noticeably smaller opening relative to its wall thickness. That thick wall is the trade-off for handling pressures that would collapse a vein.
Where You Can Feel Your Arteries
Every time your heart beats, it sends a pressure wave through your arterial system. You can feel this wave, your pulse, wherever an artery runs close to the surface of your skin and over a bone or firm structure. The most familiar spot is the radial artery at your wrist, on the thumb side. The brachial artery at the inside of your elbow is where blood pressure cuffs take their readings. Other pulse points include the femoral artery in your groin, the artery behind your inner ankle bone, the top of your foot, and the artery behind your knee.
How Arteries Get Damaged
The most common arterial disease is atherosclerosis, a gradual process where the inner lining of an artery becomes damaged and begins accumulating fatty deposits, fibrous tissue, and calcium. It starts when something injures the smooth inner lining of the artery, whether from high blood pressure, high cholesterol, smoking, or chronic inflammation. Fats and immune cells begin to collect beneath the surface, forming a deposit called plaque.
Over time, the body tries to wall off this plaque by covering it with a fibrous cap. This stabilizes the deposit but also narrows the artery, restricting blood flow. When this happens in the arteries supplying the heart, it can cause chest pain during exertion. If the narrowing becomes severe or the fibrous cap ruptures, it can trigger a blood clot that completely blocks the artery, leading to a heart attack or stroke depending on which artery is affected. Once plaque reaches this advanced stage, it rarely reverses on its own.
Keeping Your Arteries Healthy
Arterial stiffness, the loss of your arteries’ natural elasticity, is one of the earliest measurable signs of cardiovascular aging. Several dietary and lifestyle factors directly influence how flexible your arteries remain.
Reducing sodium intake has a surprisingly fast effect. Research on older adults shows that restricting dietary sodium improves large artery flexibility in as little as two weeks. Increasing potassium intake (through foods like bananas, potatoes, and leafy greens) further supports arterial function. On the other hand, consuming more than 10 grams of sodium per day, especially when potassium intake is low, measurably increases arterial stiffness.
The type of fat you eat matters more than the total amount. Diets high in saturated fat, trans fats, and cholesterol impair the function of the arterial lining and stiffen vessel walls. Replacing those fats with unsaturated fats from seafood, nuts, and plant oils reduces arterial stiffness. Omega-3 fatty acid supplements improve the elasticity of both large and small arteries independent of weight loss.
Sugar plays a role too. High-sugar diets cause repeated blood sugar spikes that damage arterial walls and increase stiffness. Switching to complex carbohydrates with a lower glycemic index protects vascular health. Low-carbohydrate diets have been shown to improve aortic stiffness in as little as four weeks. For people who are overweight, losing even 8 to 10 percent of body weight through dietary changes measurably improves arterial flexibility, with larger losses producing greater benefit.
Vitamins C and D also contribute. Vitamin C supports the inner lining of arteries and helps reduce central blood pressure. Vitamin D supplementation taken for longer than 12 weeks has been shown to significantly reduce central arterial stiffness compared to placebo.