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Sildenafil (Viagra®) has two actions that may be of consequence in patients with heart disease. It can lower the blood pressure, and it can interact with nitrates. It should never be used in patients who are taking nitrates.
Prostaglandins were first isolated from human semen in Sweden in the 1930s. They were so named because the researcher thought that they came from the prostate gland. In fact, prostaglandins exist and are synthesized in almost every cell of the body.
In 1864, the first barbiturate (barbituric acid) was synthesized.
If you could remove all of your skin, it would weigh up to 5 pounds.
Hypertension is a silent killer because it is deadly and has no significant early symptoms. The danger from hypertension is the extra load on the heart, which can lead to hypertensive heart disease and kidney damage. This occurs without any major symptoms until the high blood pressure becomes extreme. Regular blood pressure checks are an important method of catching hypertension before it can kill you.
![The nitrogen cycle. Numbers represent fluxes as 1012 g N per year (data from Schlesinger 1991, after](https://biology-forums.com/gallery/47/medium_33_17_02_12_7_02_17_2038129.jpeg)
![History of the number of observed sunspots during the last 250 years, which shows the ~11-year solar](https://biology-forums.com/gallery/47/medium_12359_16_06_12_7_11_02.png)