The vascular (circulation) system: what’s the difference between arteries and veins?

The vascular system consists of the blood vessels in your body; its name comes from Latini vasculum, for small blood vessel. Your heart pumps blood through the vascular system to the tissues to provide the cells with the oxygen and nutrients they need. This vascular system consists of arteries and veins. The arteries take the blood to the tissues; the veins bring it back to the heart to be cycled through the lungs before it is returned to the tissues.

Blood is oxygenated through the lungs, pumped out of the heart into arteries: the arterial vessels become smaller as they extend farther from the heart. The aorta delivers its flow to the large arteries; they, in turn, branch into smaller vessels, arterioles. The arterioles supply the tiny capillaries that nourish tissues. From the capillaries, the blood begins the journey back to the heart by way of the venous system. Veins are categorized into two interconnecting types: deep and superficial. The deep veins lie within and underneath the muscles and increase in size the closer they get to the heart. Superficial veins lie within and on top of the muscles, closer to the skin. We have thousands of smaller, superficial veins which empty into the larger, deep veins which, in turn, empty directly into the heart.

How blood travels back to the heart

Pressure forces fresh, oxygenated blood out of the heart into the arteries. This is also known as systolic blood pressure. The top number of your blood pressure reading (systolic) is the amount of (arterial) pressure behind that pump action. If your blood pressure is 120/80 mmHg, the pressure behind the force pushing your blood out into the arteries is 120 mmHg. As the blood loses oxygen into tissues, arterial blood turns into venous blood and the pressure in the blood vessel (now vein) drops to 30-20mmHg, much lower than the 120 mmHg when it left the heart. It is this lower pressure and lack of oxygen that brings it back to the heart to be re-oxygenated.

Breathing, or respiration (the movement of the diaphragm creating a negative pressure), helps in this process as does walking, when the action of the calf muscle helps to force blood upward. However, the most important factor in assisting venous blood flow back toward the heart is vein valves: tiny valves strategically located in the veins every couple of inches that open and close, allowing blood to move upward toward the heart, against the force of gravity and prevents blood from refluxing or pooling in the extremities.

Valvular Insufficiency and Reflux

When the valves in the veins are not working properly, blood cannot return in an efficient manner and gravity will tend to pull blood downward causing the blood vessels to dilate or extend (like a balloon). This is called venous (valvular) insufficiency or venous reflux and varicose veins, swelling, aching, skin changes or venous ulcers will often be the result.

Venous insufficiency and reflux can happen in the deep venous system and the superficial venous system, but it is most commonly noticed when it is in the superficial venous system and manifests itself through varicose veins.

Varicose Veins

One of the most common clinical manifestations of venous insufficiency is varicose veins. Varicose veins are enlarged, weakened, dilated veins that have weak or no valvular function and have permanently lost their ability to carry blood from the legs back up to the heart. As the blood falls back down the leg and pools due to gravity, the veins overfill giving them their typical unsightly bulging appearance. Many patients present with these symptoms: aching, weak or tired legs, especially at the end of the day, burning or itching of the skin, throbbing or swollen legs and ankles. Left untreated, varicose veins will likely worsen, resulting in increasingly severe symptoms of leg pain, increased throbbing and swelling, skin color changes, phlebitis, ulcer formation of the skin, and bleeding. The main treatment alternative is to re-route blood flow through healthy veins.

What causes valvular insuffiency and varicose veins?

Most patients who suffer from vein disease have a family history of the condition. Another factor is hormonal changes that specifically affect women. Pregnancy or birth control pills further increase your chances of developing vein disorders. Other contributing factors include prolonged standing, being overweight, and trauma to the leg.

Spider Veins

Small spider veins can appear on the skin’s surface and may look like a “starburst” or web-like formation. They are most common in the thighs, ankles, feet and face. They are either blue or red, and although aesthetically unsightly, they usually do not cause symptoms. Spider veins are usually caused by a combination of a hereditary tendency and hormonal changes such as those occurring during puberty or pregnancy. The condition usually appears after age 30, although it can sometimes develop as early as the teen years.

Spider veins are caused by abnormal blood flow and weakening of the blood vessel wall in the affected veins. Any condition or activity that puts pressure on the veins such as gaining weight, and sitting or standing for long periods of time can contribute to their development.

Although spider veins are not usually symptomatic, the accompanying reticular veins, found deeper in the skin, often cause discomfort. Reticular veins are also referred to as "feeder" veins. Many women have a combination of both varicose and spider veins. While they may seek treatment for cosmetic improvement, many female patients are in fact looking for relief from pain.

Women account for approximately 85-90% of varicose vein and spider vein cases, mainly because of the unique additional risk factors for females, including estrogen levels and pregnancy. Women are particularly afflicted with reticular veins. These light blue veins usually appear in a lattice framework, giving a marbled appearance to the skin. They are the most harmless-looking veins, but they are usually the most symptomatic of all.

In men, the pathophysiology is similar, but instead of reticular veins, the culprits are multiple, small-branching varices and "high pressured small vein disease". The varices, unfortunately, are often mistaken for "cosmetic" telangiectasia (spider veins). Spider veins are a common cosmetic concern for both women and men.