Vasodilation is the enlargement of blood vessels. It occurs when the muscles in the vessel walls get relaxed. Vasodilation can affect the arterial resistance.
What is vasodilation?
Vasodilation is a survival tactic of warm-blooded animals. There are certain temperature limits to which their body needs to stick. When the external temperature rises and crosses that limit, the body will make adjustments to its blood vessels for adaptation. The blood vessels closest to the body’s extremities will dilate, allowing warm blood to get close to the skin. When it is, the heat from the blood can get out of the body, and get absorbed by the external environment. The animal gets to keep its optimal temperature. The opposite of vasodilation is vasoconstriction, a condition in which the blood vessels are narrowed down. Vasoconstriction usually happens to large arteries as a natural tactic to get the most effective result. However, in some special cases of human, it can affect small arterioles as well. Since the body needs blood to operate all the time, vasodilation and vasoconstriction can anytime at any part of the body.
Causes of vasodilatation
Causes of vasodilatation are referred to vasodilators. The nervous system itself can trigger vasodilation with abnormal releases of hormones and neural signals. Medicines can cause vasodilation as well. Most medicinal vasodilators are drugs prescribed for high blood pressure, commonly known as hypertension. Other medical conditions that may require the use of medicinal vasodilators are angina (chest pain) and congestive heart failure. In addition, numerous chemicals can lead to vasodilation too. Histamine and lactic acid are prominent examples. Physical activities are known as the cause of the dilated blood vessels. External factors such as abnormal noise or light in the living habitat may cause sudden dilation of the blood vessels.
Vasodilation and arterial resistance
As mentioned above, vasodilation can affect the relationship between the average blood pressure, the volume of blood supplied by the heart, and the total resistance to the flow of the systemic circulation. Vasodilation occurs during the contraction of the cardiac cycle. The resistance depends on the viscosity of blood, the length, and diameter of the blood vessel. Vasodilation decreases the resistance and the blood pressure by getting the muscles in the walls of the arteries and arterioles. An increase in either the blood flow volume or the resistance will raise the average blood pressure.
It is safe to say that if a drug is determined to cause vasodilation, maintaining the use of it might be necessary due to is beneficial effects to the patient’s health. It’s also important to those with a chronic disease like high blood pressure. To come up with a solid treatment plan, you will need to weigh the advantages against the side effect.
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Review Date: January 20, 2017 | Last Modified: January 20, 2017
Siddiqui, A. (2011). Effects of Vasodilation and Arterial Resistance on Cardiac Output. Journal Of Clinical & Experimental Cardiology, 02(11). http://dx.doi.org/10.4172/2155-9880.1000170.
What is Vasodilatation? http://www.wisegeekhealth.com/what-is-vasodilatation.htm. Assessed October 15, 2016.