What is a vascular smooth muscle?
Cardiovascular system or heart and blood vessels give oxygen and nutrients to all body tissues and are essential for survival. Smooth muscles play an important role in normal anatomy and physiology of blood vessels. Vascular smooth muscle (VSM) is a type of smooth muscle found in the walls of the blood vessels. A wall cell is a term that refers to a combination of connective tissue cells called pericytes and cells of the smooth muscles of blood vessels in blood vessels. The presence of vascular smooth muscles in the blood vessels allows the latter to respond to changes in blood volume and pressure, increasing tissue supply that requires blood and reducing tissues with less demand. Generally, arteries have more of these muscles than veins. This is explained by the fact that arteries are exposed to higher pressure due to pumping action. Therefore, coarse and microscopic examination of blood vessels would reveal that arteries have thicker walls than veins.
Like the skeletal muscle, the contraction of the vascular smooth muscles is controlled by the nervous system. Unlike skeletal muscles that are voluntarily controlled, the vascular smooth muscles are innervated by the autonomic nervous system, especially the sympathetic nervous system. Like the heart muscle, the vascular smooth muscle of actin and myosin contains. It does not have a protein called Troponin, which is located in the heart muscle. In addition, while the heart muscle contrasts quickly and quickly every few hundred milliseconds, vascular smooth muscles slowly permanently and tonic.
Vascular smooth muscle has several receptors that allow it to respond to signals from the sympathetic nervous system or to sympathetic stimuli. These receptors are Alfa-1, Alfa-2 and Beta-2 receptors. When the Norepinephrin neurotransmitter binds to Alfa-1 receptors, the vascular smooth muscles are contraction, resulting in a reduction in blood vessel diameter or vasoconstriction. Once Alfa-2 receptors are activated, there is also vasoconstriction. When beta-2 receptors are activated by vasodilation or increases the diameter of the blood vessel.
Vascular smooth muscle receptors are important when checking blood pressure. For example, people who have a severe allergic reaction called anaphylactic shock usually have very low blood pressures. To restore blood pressure on normal, drugs stimulating alpha-1 receptors such as epinephrine are administered. Alternatively, there are people who have high blood pressures, drugs such as prazosin or doxazosine that antagonize or are against the effect of alpha-1 receptor stimulation, are given by blood vessels vasodilation and reduce blood pressure.