What Is an Arteriole?
The diameter of the tube is between 0.3 and 1 mm. It is a small artery. The small arteries include branches of varying thickness and are also muscular arteries. Large arterioles, the inner membrane has a distinct inner elastic membrane, the media membrane has several layers of smooth muscle, the thickness of the outer membrane is similar to the media membrane, and there is generally no outer elastic membrane.
- Chinese name
- Arterioles
- Foreign name
- arteriola
- The diameter of the tube is between 0.3 and 1 mm. It is a small artery. The small arteries include branches of varying thickness and are also muscular arteries. Large arterioles, the inner membrane has a distinct inner elastic membrane, the media membrane has several layers of smooth muscle, the thickness of the outer membrane is similar to the media membrane, and there is generally no outer elastic membrane.
Overview of the arterioles :
- The structure of the tube wall is similar to that of the middle artery, but each layer is thinner, the inner elastic membrane is obvious, the middle membrane contains several layers of smooth muscle, and the outer elastic membrane is not obvious. Arteries are also called peripheral resistance blood vessels.
Physiological anatomy of arterioles:
- For arteries with a diameter of less than 1mm, the wall of the tube has a complete smooth muscle layer and a small amount of elastic and glial fibers. The arterioles are the main factor that determines the resistance of the surrounding circulation, and also the "total switch" that regulates the volume of microcirculation perfusion. Typical arterioles have a wall thickness of about 1: 2 compared to the tube diameter. The medial layer is thicker than other arteries. When smooth muscle contracts strongly under innervation, its lumen can be completely occluded, so that blood cannot flow into the capillaries it distributes, thereby increasing the resistance to peripheral blood circulation. . If many small arteries contract at the same time, blood pressure can rise significantly. Conversely, when the smooth muscles of the arterioles are relaxed, a large amount of blood can flow into the capillaries, the peripheral resistance is significantly reduced, and the blood pressure is reduced. The caliber of the terminal arteriole is 20 to 30 m; the caliber of the posterior arteriole (also known as precapil-lary arteriole) is 12 to 15 m. There are sparse smooth muscles in the tube wall. At the beginning of the anterior arteriolar branch of the capillary, the smooth muscle component of the tube wall is thickened. It is called the precapillary sphinc-ter, and its contraction or relaxation can adjust the true capillary. The blood flow of blood vessels is a "sub-switch" that regulates the amount of microcirculation perfusion. Sympathetic nerve fibers that innervate arterial smooth muscle can extend to smooth muscle cells of terminal arterioles and posterior arterioles. Sympathetic nerve fibers are particularly abundant on the anterior sphincter of capillaries.