The Mysterious Purr

[voodidit]

One of the cat’s most unique characteristics is purring. Although purring is associated with contentment, cats have been heard to purr when in pain, anxious or nervous. How cats purr has long been studied. One popular explanation, not accepted by all zoologists, is that purring results from the vibration of false vocal cords, two folds of the membrane behind the cords in the larynx. Another theory is that purring is the result of an increased blood flow in the vena cava, the main artery returning blood to the heart. This vein constricts to pass the liver and diaphragm. When the cat arches its back, the blood flow eddies and becomes turbulent in this narrow area, setting up the vibrations we call purring.

http://pets.yahoo.com/pets/cats/hn/the_mysterious_purr

[Makat2u]

That's one of the things I love about cats is their purr