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.
What is Heart Disease. A heart attack (myocardial infarction) occurs when blood flow to a part of your heart is blocked for a long enough time that part of the heart muscle is damaged or dies. Learn more. Heart disease is one of several cardiovascular diseases, which are diseases of the heart and blood vessel system.