kálcium

Kálcium is a chemical element with the symbol Ca and atomic number 20. It is a soft, grayish alkaline earth metal. Calcium is the fifth most abundant element in the Earth's crust and is found naturally in many minerals, most notably limestone and gypsum. It is also a vital component of biological organisms.

In living things, calcium plays a crucial role in many physiological processes. The vast majority of calcium in mammals is found in their bones and teeth, where it provides structural support. It is also essential for muscle contraction, nerve signaling, and blood clotting. Calcium is absorbed from the diet, primarily in the small intestine, and its absorption is regulated by vitamin D.

Calcium compounds have a wide range of industrial and domestic uses. Calcium carbonate, for example, is used in construction materials like cement and lime, as well as in antacids and as a dietary supplement. Calcium oxide, also known as quicklime, is a key ingredient in steelmaking and various chemical processes. Calcium chloride is used as a de-icing agent and a desiccant.

A deficiency in calcium can lead to health problems such as osteoporosis, a condition characterized by weakened bones, and rickets in children. Conversely, excessive calcium intake, although less common, can cause hypercalcemia, which can lead to kidney stones and other health issues.