The heart and blood vessels are collectively responsible for maintaining a continuous flow of blood through the body, known as the circulatory system. This provides all the body tissues with a regular supply of oxygen and nutrients, and carries away carbon dioxide and other waste products.
The circulatory system consists of two main parts: the systemic circulation, which constitutes the blood supply to the entire body except the lungs; and the pulmonary circulation, which carries blood to and from the lungs where its supply of oxygen is replenished.
On its journey from the heart to the tissues, blood is forced along the arteries at thigh pressure. On the return journey through the veins back to the heart, it is at low pressure, kept moving by the muscles in the arms and legs compressing the walls of the veins and by valves in the veins preventing the blood from flowing backwards. Lack of exercise or a sedentary lifestyle may therefore be at the root of circulatory problems.
Poor circulation may also be the result of, or indeed the cause of, some disorders of the arteries or veins such as an abnormal narrowing (reducing blood flow and possibly causing tissue damage) or abnormal widening and thinning of the walls (increasing the risk of rupture). Symptoms of poor circulation can range from Raynaud’s disease through varicose veins to chest pains and leg pains in cases of severe arteriosclerosis (thickening and loss of elasticity of the artery walls). Poor circulation is particularly prevalent in those who are overweight or who drink too much alcohol. Heavy smokers are advised to cut down because nicotine reduces the blood circulation in the skin.