Difference between a venule and an arteriole
An arteriole is also a component of the final flow path of the vascular system and resembles an artery in its wall structure. The arteries generally have a larger and more compact muscle layer than the veins. The arterioles form the resistance vessels in the body’s circulation and therefore have a significantly thicker muscle layer than the venules.
The wall layer of smooth muscle cells serves to regulate blood pressure in the subsequent capillaries. The upstream arteries conduct the blood with high blood pressure. This pressure is strongly reduced in the area of the arterioles and individually adjusted for each subsequent organ. For example, in the event of a large loss of blood, they can throttle the blood flow in the final flow path so that the remaining blood is centralized. This function is essential for maintaining cardiovascular stabilization.
What is a shunt?
A shunt is an arteriovenous anastomosis, i.e. a direct transition from an arteriole to a venule, without an intermediate capillary bed. These shunt connections can be used to regulate the blood flow in the adjacent capillary beds. Thus, some capillary beds can be switched off completely if necessary.
The blood flow is also regulated by the wall muscles of the arterioles. During a shock, the regulation of capillary blood flow can be lost. As a result, there is more blood in the capillaries and the central vessels and the heart lacks this blood, which can lead to circulatory failure.
