The changes in the shape of a vein are primarily due to transmural pressure , which is the difference between the internal and external pressures acting on the vein. This type of pressure causes the vein walls to stretch in response to varying blood volumes. Other pressures mentioned do not directly impact vein shape in the same way. ;
The pressure responsible for changes in the shape of a vein is mainly transmural pressure , which is the difference between the pressure inside the vein and the pressure outside it. As blood volume fluctuates, the transmural pressure causes the vein walls to stretch or shrink accordingly. Other types of pressure do not directly affect vein shape in the same manner.
;