With water, colder and saltier equals denser. At the earth's poles, when water freezes, the salt doesn't necessarily freeze with it, so a large volume of dense cold, salt water is left behind. When this dense water sinks to the ocean floor, more water moves in to replace it, creating a current. The new water also gets cold and sinks, continuing the cycle. Incredibly, this process drives a current of water around the globe.
Medical Definition of HEART DISEASE. : an abnormal organic condition of the heart or of the heart and circulation.See heart disease defined for kids.ADVERTISEMENT.edical Definition of HEART DISEASE. : an abnormal organic condition of the heart or of the heart and circulation.
Coronary heart diseaseâoften simply called heart diseaseâis the main form of heart disease. It is a disorder of the blood vessels of the heart that can lead to heart attack. A heart attack happens when an artery becomes blocked, preventing oxygen and nutrients from getting to the heart. Heart disease is one of several cardiovascular diseases, which are diseases of the heart and blood vessel system. Other cardiovascular diseases include stroke, high blood pressure, angina (chest pain), and rheumatic heart disease.