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 ischemic heart disease? Ischemic heart disease is a condition of recurring chest pain or discomfort that occurs when a part of the heart does not receive enough blood. This condition occurs most often during exertion or excitement, when the heart requires greater blood flow. Ischemic heart disease, also called coronary heart disease, is common in the United States and is a leading cause of death worldwide. Ischemic heart disease develops when cholesterol particles in the blood begin to accumulate on the walls of the arteries that supply blood to the heart. Eventually, deposits called plaques may form. These deposits narrow the arteries and eventually block the flow of blood.