For now, not enough data exists on the safety of e-cigarettes, how the health effects compare to traditional cigarettes, and if they are helpful for people trying to quit smoking. Points to Remember Electronic cigarettes are battery-operated devices that people use to inhale an aerosol, which typically contains nicotine (though not always), flavorings, and other chemicals. In many e-cigarettes, puffing activates the battery-powered heating device, which vaporizes the liquid in the cartridge or reservoir.
Muscular, or distributing, arteries deliver blood to specific body organs, and have the greatest proportion of tunica media of all vessels, making them more active in vasoconstriction. Arterioles are the smallest arteries and regulate blood flow into capillary beds through vasoconstriction and vasodilation.Capillaries are the smallest vessels and allow for exchange of substances between the blood and interstitial fluid.Continuous capillaries are most common and allow passage of fluids and small solutes. Fenestrated capillaries are more permeable to fluids and solutes than continuous capillaries.inusoidal capillaries are leaky capillaries that allow large molecules to pass between the blood and surrounding tissues. Capillary beds are microcirculatory networks consisting of a vascular shunt and true capillaries, which function as the exchange vessels.
Medical Definition of Capillaries Capillaries: Capillaries are the smallest of blood vessels. They serve to distribute oxygenated blood from arteries to the tissues of the body and to feed deoxygenated blood from the tissues back into the veins. The capillaries are thus a central component in the circulatory system, essentially between the arteries and the veins. When pink areas of skin are compressed, this causes blanching because blood is pressed out of the capillaries.