The familiar sounds of your heart are made by the heart's valves as they open and close.
Did you know?
When Gabriel Fahrenheit invented the first mercury thermometer, he called "zero degrees" the lowest temperature he was able to attain with a mixture of ice and salt. For the upper point of his scale, he used 96°, which he measured as normal human body temperature (we know it to be 98.6° today because of more accurate thermometers).
Did you know?
Blood is approximately twice as thick as water because of the cells and other components found in it.
Did you know?
Drugs are in development that may cure asthma and hay fever once and for all. They target leukotrienes, which are known to cause tightening of the air passages in the lungs and increase mucus productions in nasal passages.
Did you know?
There are 20 feet of blood vessels in each square inch of human skin.
