What are veins?
In most parts of the body, the veins run parallel to the arteries. Since the blood is returned to the heart mainly by the veins, the blood pressure in the veins is lower than that in the arteries. As a result, the wall of the veins is weaker, which is why our veins are equipped with the small venous valves. When the blood flows in the direction of the heart, the venous valves are open like small vents which close again as soon as blood flows in the wrong direction. This ensures a smooth flow of blood back to the heart and prevents congestion in the blood vessels.
Within the space of 24 hours around 7,000 liters of blood flow through our veins – upwards against gravity towards the heart. The leg veins contribute significantly to the return of the blood and perform very hard work which is supported only by the foot and leg muscles and our respiration.
Veins - a weak point
The weak points of the veins are the venous valves. These essentially perfect little valves force the blood to flow only in one direction. This works well until the veins are no longer able to close properly due to being overstretched. The function of the valves is then lost and the blood accumulates inside the veins. The pressure in the veins eventually becomes so high that liquid seeps from the venous tissues into the surrounding connective tissue, where it leads to swelling or so-called oedemas. Possible consequences: The blood accumulates in the feet and the legs and the return of the blood to the heart is massively impaired.
There are many factors that can cause venous problems. It is not without reason that "lack of movement" is in the first place. However, also physical changes such as severe overweight, pregnancy and advancing ageing of the skin play are possible causal factors. Predisposition also plays a role in regulating the amount of collagen fibres formed in the connective tissue. Last but not least, insufficient food and fluid intake can also contribute to a decrease in elasticity of the connective tissue over time.
For example, if the leg muscle pump that effectively supports the circulation of blood by movement of the muscles no longer gets enough exercise, the muscles relax and the surrounding tissue becomes weaker. The dwindling elasticity results in increased pressure in the legs veins and arteries, which in turn leads to excessive dilation of the venous walls and incomplete closure of the venous valves.
Venous disorders are widespread and are frequently played down by saying "just elevate the legs and it will soon get better". If your legs feels increasingly heavy, your ankles become swollen, your legs are often painful, are smaller in the morning than in the evening, develop varicose veins, then you should have your leg veins examined by a specialist, a so-called phlebotomist.
How does the blood get into the veins?
With every heartbeat, blood is pumped away from the heart through the arteries and through the entire body. The greater circulation starts in the left side of the heart. If you imagine the network of blood vessels in the human body as a tree, then the main trunk can be compared to the main artery, the aorta. Two main branches, which then branch off into small blood vessels called arteries, leave the aorta. At the end of these arteries there are very small branches, the smallest blood vessels, known as capillaries. When blood passes through the capillaries, an oxygen exchange into the tissue and cells takes place. The small capillaries then gather in again to become larger vessels, known as venules. These tiny veins transport the blood back into the next larger vessels, the veins. The veins are responsible for carrying the blood back to the heart via the upper and lower vena cava, and transport the blood via the main vein back into the right heart valve, the right atrium.
Muscles compress the vessels
If you get exercise by going for a walk, you activate the muscles of the calf, which act as a muscle pump. When the muscles are tensed, the blood vessels (also called just "vessels") are compressed. This helps to pump the blood from the legs back towards the heart. The venous valves inside the veins prevent the blood from flowing back down into the legs. While the deep veins are emptied, blood from the superficial veins flows back down via the connecting veins.
Long periods of standing or sitting and altogether a lack of movement and exercise of the leg muscles are often the reason why not enough blood is pumped out of the legs. The veins become increasingly filled and dilated. Due to the increase in cross-section of the veins the valves are no longer able to close properly, so that even more blood flows back into the legs.
If the muscle pump is not exercised enough
When muscles get barely any exercise, this leads to a reduction in the muscles' pumping function. After a subsequent dilation of the blood vessels, the walls of the vessels now become permeable, allowing tiny particles such as proteins from entering the tissue through the vessel. Just like e.g. salt, protein has the ability to bind to water. However, the body wants to protect itself from the "unknown" substances in the tissue, and triggers an inflammatory response. This defensive and protective reaction of the body leads to an even greater permeability of the vessels. This development leads to serious consequences.