The circulatory system
Blood circulation is divided into arterial circulation and venous circulation: if the first brings blood from the heart to the periphery, the second collects blood from the periphery, bringing it back to the heart. Its main function is to transport nutrients and waste products (catabolites) into the body.
Arteries and Veins
The vessels in which the circulatory system is organized can be distinguished in arteries and veins: they are essentially conductive pathways, which decrease in diameter as we move away from the main vessels towards the peripheral areas of the body. At the level of the tissues the arterial circle constitutes the so-called microcirculatory system, a system of arterioles that spreads ubiquitously throughout the body and flows into a dense network of capillary vessels. The anatomical conformation of the wall of these microvessels, composed of a thin layer of cells, makes it highly permeable, allowing the easy transfer of oxygen and nutrients to the tissues, and the recovery of waste products from them.
Importance of the Lymphatic Circle
Next to the bloodstream is the lymphatic circulation, a complex system of vessels, also ubiquitous with respect to the different parts of our body, which plays the fundamental role of drainage of the interstitial fluid. Simultaneously with the transfer of oxygen and nutrients to the tissues, in fact, proteins and a fluid component of the blood are also released outside the vessels and only partly reabsorbed by the venous system. In this way 10% of what is filtered by the blood capillaries remains in the interstitial spaces present between one cell and another, and then recovered from peripheral lymphatic or capillary lymphatic vessels. These are identified in small tubular vessels with a blind bottom and very high permeability, whose structure allows the interstitial fluid to be completely absorbed and transported, in the form of lymph, to the venous circulation. Since there is no propulsion organ, the circulation of the lymph occurs mainly due to the rhythmic contractile activity of the vascular musculature which, thanks also to the presence of valves, pumps the lymph towards the larger diameter vessels. The lymphatic system flows into the venous circulation, causing the interstitial fluid to be completely recirculated into the bloodstream.
The function of the lymphatic circulation is therefore fundamental: if the interstitial fluid were not reabsorbed by the lymphatic system there would be an increase in the leakage of liquids from the arterial capillaries, and there would be the formation of edemas (accumulations of liquids in the interstitial spaces) very dangerous .
Circulatory disorders in the lower limbs are often associated with an increase in the permeability of arterial capillaries, which manifests itself with an increase in fluids poured into the interstitial spaces. This phenomenon can initially be kept under control by the microlymphatic drainage system, which, however, following the persistence of the disorder and an excessive accumulation of intracellular liquids, at a certain point is no longer able to effectively perform its functions, with a consequent increase in the stasis of the edema in the tissues.
Circulatory problems in the lower limbs
A problem ... Modern
In humans the venous pressure measured at the ankles can reach 85mmHg in physiological conditions, but with walking, it decreases up to 25mmHg. Therefore, frequent and regular walks are able to offer an important protection in healthy subjects against the pathological effects due to the increase in peripheral venous pressure.
With the advent of "modern life" our habits have become more sedentary and we often find ourselves standing still or sitting for long periods throughout the day. This causes a decrease in the drainage capacity of liquids from the most peripheral parts of our body; consequently, you start to feel symptoms such as pain, swelling and tiredness, especially in the lower limbs.
Venous Return: what is it?
Microcirculation Alterations
As blood stasis progresses in the peripheral districts, the normal physiological state of the microcirculation is altered. In fact, a cascade inflammatory reaction triggers which has the consequence of increasing the permeability of the capillaries and the escape of red and white blood cells, and of large molecules, in the surrounding tissues. Around the capillaries and venules a kind of "sleeve" is formed which acts as a barrier and prevents the oxygenation and release of nutrients to the tissues. In these districts there is therefore the accumulation of waste materials and a reduction in tissue oxygenation.
Due to its extension, the skin is the organ that contains the greatest amount of small blood vessels and is therefore the main target organ of microcirculatory stasis. With the formation of oedemas at the level of the dermis, its most vascularized part, and the exudation of liquids, inflammation extends into the subcutaneous fatty tissue, the first stage of cellulite formation. This, which is considered a real pathology, begins with a stagnation of liquids also in the subcutaneous tissue, with a reduced tissue oxygenation and an accumulation of fat and water in the cells, and then evolves with the formation of painful macronodules.
Causes
Venous microcirculation disorders are more frequent in women than in men, in an estimated ratio of 3: 1, although the incidence in men increases with advancing age. It is however very likely that genetic inheritance is the most important risk factor.
There are also predisposing factors that can favor the onset of microcirculatory disorders. Among these we remember:
- Posture, intended both as standing still for a long time, as a sedentary lifestyle
- obesity
- Wrong lifestyles (eg unbalanced diet, smoking)
- The pregnancy
- Use of oral contraceptives
- Any previous venous thrombosis.
Strengthen the microcirculation: prevention and cosmetics »
