Homeostasis

http://health.howstuffworks.com/human-body/systems/endocrine/adam-200092.htm
Do you know what the difference between cold and warm blooded animals? Well, warm blooded animals can keep their body temperature at a constant temperature, cooling their body in hot surroundings and warming their bodies in cold surroundings, whereas for cold blooded animals, their body temperature changes with the surroundings. It is general knowledge. But there is more to that than just keeping their body temperature constant.
Homoeostasis is the maintenance of a relatively constant internal environment like body temperature, blood and tissue fluid. It is amazing to see how the human body can adapt itself, to adjust and prevent change in our bodies.