The Urinary System

Upon hearing from my teacher that tea and coffee are diuretics, meaning stimulates peeing, I was curious as to why that was. So I don't have a terribly specific question, rather, what can I learn about this?
The first interesting thing I discovered is that there are many websites and blogs dedicated to tea alone. But among these, I gathered many interesting facts on tea as a possible diuretic. 
Tea leaves that contain caffeine have diuretic properties, however, in order to experience diuretic effects one would have to drink enough cups of tea to take in 300 mg of caffeine which would be roughly 6 cups of regular caffeinated tea, according to these sites. 

http://theteamaestro.blogspot.ca/2012/03/does-drinking-tea-produce-diuretic.html

http://www.yourteahq.com/diuretic-tea/


While there are clear negative effects of ingesting too many foods with diuretic properties (such as dehydration), diuretics may be helpful in lowering high blood pressure and promoting the urinary system to excrete toxins in the blood. 
In fact, diuretic pills are used to help people with illnesses such as edema.

http://www.yourteahq.com/diureticgreentea/





















While tea may have many health benefits, the caffeine in the leaves can have diuretic effects, so when it comes to tea, there does exist the idea of having too much of a good thing.