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.
Heart disease: Any disorder that affects the heart. Sometimes the term heart disease is ... Heart failure: Inability of the heart to keep up with the demands on it and, specifically... Heart rate: The number of heartbeats per unit of time, usually per minute. The heart rate ... Heart rhythm disorders: Abnormal rhythm of the heartbeat due to irregularities in transmis... High blood pressure: A repeatedly elevated blood pressure exceeding 140 over 90 mmHg.