Vasodilator in the context of Perfusion


Vasodilator in the context of Perfusion

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⭐ Core Definition: Vasodilator

Vasodilation, also known as vasorelaxation, is the widening of blood vessels. It results from relaxation of smooth muscle cells within the vessel walls, in particular in the large veins, large arteries, and smaller arterioles. Blood vessel walls are composed of endothelial tissue and a basal membrane lining the lumen of the vessel, concentric smooth muscle layers on top of endothelial tissue, and an adventitia over the smooth muscle layers. Relaxation of the smooth muscle layer allows the blood vessel to dilate, as it is held in a semi-constricted state by sympathetic nervous system activity. Vasodilation is the opposite of vasoconstriction, which is the narrowing of blood vessels.

When blood vessels dilate, the flow of blood is increased due to a decrease in vascular resistance and increase in cardiac output. Vascular resistance is the amount of force circulating blood must overcome in order to allow perfusion of body tissues. Narrow vessels create more vascular resistance, while dilated vessels decrease vascular resistance. Vasodilation acts to increase cardiac output by decreasing afterload, −one of the four determinants of cardiac output.

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Vasodilator in the context of Prostaglandin E1

Prostaglandin E1 (PGE1) is a naturally occurring prostaglandin with various medical uses. Alprostadil and misoprostol are synthetic forms of prostaglandin E1 used as medications. Lubiprostone, a derivative of prostaglandin E1, is also used as a medication. Prostaglandin E1 is a vasodilator. It has various effects in the body that include opening blood vessels, relaxing smooth muscle, inhibiting clotting, and causing uterine contractions.

In infants with certain congenital heart defects, alprostadil is delivered by slow injection into a vein to maintain a patent ductus arteriosus until surgery can be carried out. By injection into the penis or placement in the urethra, alprostadil is used to treat erectile dysfunction. Common side effects when given to babies include decreased breathing, fever, and low blood pressure. When injected into the penis for erectile dysfunction; side effects may include penile pain, bleeding at the site of injection, and prolonged erection (priapism). Prostaglandin E1 was isolated in 1957 and approved for medical use in the United States in 1981.

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Vasodilator in the context of ACE inhibitors

Angiotensin-converting-enzyme inhibitors (ACE inhibitors) are a class of medication used primarily for the treatment of high blood pressure and heart failure. This class of medicine works by causing relaxation of blood vessels as well as a decrease in blood volume, which leads to lower blood pressure and decreased oxygen demand from the heart.

ACE inhibitors inhibit the activity of angiotensin-converting enzyme, an important component of the renin–angiotensin system which converts angiotensin I to angiotensin II, and hydrolyses bradykinin. Therefore, ACE inhibitors decrease the formation of angiotensin II, a vasoconstrictor, and increase the level of bradykinin, a peptide vasodilator. This combination is synergistic in lowering blood pressure.

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Vasodilator in the context of Vasomotor

Vasomotor refers to actions upon a blood vessel which alter its diameter. More specifically, it can refer to vasodilator action and vasoconstrictor action.

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Vasodilator in the context of Vascularity

Vascularity, in bodybuilding, is the condition of having many highly visible, prominent, and often extensively-ramified superficial veins. The skin appears "thin"—sometimes virtually transparent—due to an extreme reduction of subcutaneous fat, allowing for maximum muscle definition.

Vascularity is enhanced by extremely low body fat (usually below 10%) and low retained water, as well as the muscle engorgement ("pump") and venous distension accentuated by the vigorous flexing and potentially hazardous Valsalva effect which characterize competitive posing. Genetics and androgenic hormones will affect vascularity, as will ambient temperature. Additionally, although some bodybuilders develop arterial hypertension from performance-enhancing substances and practices, "high" venous pressure—being an order of magnitude lower than that of arteries— neither causes nor is caused by vascularity. Some bodybuilders use topical vasodilators to increase blood flow to the skin as well. Although historically controversial, vascularity is a highly-sought-after aesthetic for many male bodybuilders, but less so for female bodybuilders, where the target aesthetic is relatively more towards aesthetic symmetry than extreme development.

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