Bark (botany) rope, used for example in the rigging of Viking age longships. Among the commercial products made from bark are cork, cinnamon, quinine (from the bark of Cinchona) and aspirin (from the bark of willow trees). The bark of some trees notably oak ("Quercus robur") is a source of tannic acid, which is used in tanning. Bark chips generated as a by-product of lumber production are often used in bark mulch in western North America. Bark is important to the horticultural industry since in shredded form it is used for plants that do not thrive in ordinary soil, such as epiphytes.
Mechanism of action of aspirin form blood clots. Low-dose, long-term aspirin use irreversibly blocks the formation of thromboxane A in platelets, producing an inhibitory effect on platelet aggregation. This antiplatelet property makes aspirin useful for reducing the incidence of heart attacks; heart attacks are primarily caused by blood clots, and their reduction with the introduction of small amounts of aspirin has been seen to be an effective medical intervention. A dose of 40 mg of aspirin a day is able to inhibit a large proportion of maximum thromboxane A release provoked acutely, with the prostaglandin I2 synthesis being little affected; however, higher doses of aspirin