How the brain controls contraction and relief of muscles and blood flow in the veins Physics helped to describe the body movement and the movement of fluids in the vein system. Therefore medical doctors can better detect problems of the human heart and all diseases related to veins. The body movement was described in the physics, but the description was on mechanical base that does not explain why the brain controls muscles and how it is done. Blocked veins cause insufficiency of the oxygen in some parts of the human body. Therefore these parts lack energy to work properly.
Doctors mostly solve problems of mechanical blocks in the veins.
There exist also temporary blocks in the vein system that are not mechanical. These blocks are caused by the contraction of veins. This problem can cause limited supply of blood and oxygen in the tissues. However the tissue dies of the insufficiency of oxygen for limited blood flow to this tissue. The cause of that is in bad control of muscles or blood flow through veins.