Final answer:
Vasoconstriction and vessel smooth muscle contraction are mechanisms known as vasoconstriction and vasodilation. Smooth muscles in the walls of blood vessels can contract to cause vasoconstriction, which narrows the lumen of blood vessels. This results in decreased blood flow and increased blood pressure.
Step-by-step explanation:
Vasoconstriction and vessel smooth muscle contraction are mechanisms known as vasoconstriction and vasodilation. Smooth muscles in the walls of blood vessels can contract to cause vasoconstriction, which narrows the lumen of blood vessels. This results in decreased blood flow and increased blood pressure. On the other hand, relaxation of these muscles causes vasodilation, which widens the lumen and increases blood flow while reducing blood pressure.
Vasoconstriction and vessel smooth muscle contraction are important mechanisms for regulating blood pressure and blood flow in the body. They are controlled by the autonomic nervous system and can be influenced by hormones and local chemicals.