Blood vessels
The blood vessels are the tubes through which flows the blood. There are mainly three types of blood vessels:
- The arteries are the blood vessels leading from the heart. It has elastic and resistant walls, as well as a powerful muscular layer that regulates the pressure with which the blood leaves the heart. With ventricular systole, blood leaves the heart filling the artery and the sigmoid valves close so that it cannot back up .
The arteries are made up of three layers, the muscular layer being very thick since its contractions help drive the blood.
The arteries, as they move away from the heart, branch into other thinner and less elastic vessels called arterioles.