Or they pretend not to believe. In my opinion, they rather grimace.
Many blood vessels have muscles in their walls. These are smooth muscles. They differ from skeletal muscles in that they cannot flutter and twitch quickly. They are gradually being reduced.
Most of the muscles are in the walls of the arteries. Due to the contraction of such muscles, the lumen of the arteries narrows. This increases blood pressure, or restricts blood flow to where blood does not need to flow.
And where shouldn't the blood flow? Well, if, for example, a person freezes, then the body narrows blood vessels in order to limit the flow of warm blood to the skin. This way we lose less heat.
The veins also have muscles, but there are few of them. Due to this, the veins are easily overflowing with blood. This is normal. This is how they should work.
Sometimes, of course, the pliability of the veins plays a cruel joke with them, and the veins expand where they did not need to expand. Varicose veins and all that.
Usually, the muscles inside the vessels contract evenly, and the vessel becomes narrow for some extent. But there are also lymphatic vessels in which muscles contract in waves.
It is not blood that flows in the lymphatic vessels, but lymph. This lymphatic system does not have a pump like the heart, so there are muscles in the lymph vessel wall that contract in waves. The lymphatic vessel thus becomes similar to the intestine. Due to the wave-like contractions of the muscles in the wall of the lymphatic vessels, the lymph slowly moves towards the center of our body.
In general, from the muscles in the vascular wall there is not only benefit, but also harm. If the muscles in the arteries sway and contract constantly, then blood pressure will be constantly high. It's unhealthy.
And the muscles in the arteries are also involved in the development of atherosclerosis. It is with muscle cells that all these atherosclerotic plaques are associated.
So there are muscles in the vessels. You can be sure. I will say more - there are even other vessels inside the vessels. That is, the blood vessels that supply blood to the blood vessels. Is it true?
