A frog gets rid of it's urine through the kidneys because the heart pumps blood throughout the body, the lungs are used to take in O2 molecules and gills are use to filter out the hydrogen in HO2 so they can breathe under water. However the kidneys are part of the waste disposal system (what makes us need trip to the bathroom ever now and then) therefore that is the answer.<span />
Earth is a planet, Zero planets on earth
Mitral valve prolapse severe enough to cause regurgitation may directly cause INCREASE pressure in the LEFT atrium. Mitral valve prolapse is a medical condition in which the the two valve flaps of the mitral valve do not close properly, bulging upward into the left atrium. The condition may be mild or severe. Heart surgery may be required in case of the severe one.
Heat can travel from one place to another in three ways: Conduction, Convection and Radiation. Both conduction and convection require matter to transfer heat. If there is a temperature difference between two systems heat will always find a way to transfer from the higher to lower system
The warming of said environment or planet. by emitting carbon and other gasses that create a thin layer of different gasses that trap the heat from the suns rays and breaks down the ozone layer.