Calcium

CALCIUM

Calcium is a chemical element. The chemical symbol is Ca and the atomic number is 20. Calcium is a silver-white alkaline earth metal with moderate ductility. Although the content in the earth's crust is also very high, it is the fifth most abundant element in the earth's crust, accounting for 3% of the total mass of the earth's crust [2]. Because of its high chemical activity, it can react with water or acid to emit hydrogen gas, or it can It can be oxidized (form a dense oxide layer (calcium oxide)), so it exists in ionic state or compound form in nature, and no element exists.

Calcium is an alkaline earth metal, and its physical and chemical properties are similar to its heavier family elements barium (Ba) and strontium (Sr). It is the fifth most abundant element in the earth's crust, accounting for 3% of its total mass, and the third most abundant metal in the earth's crust, second only to iron and aluminum. The name comes from the Latin calx (lime), which can be obtained by heating limestone.

Although many compounds of calcium have been discovered a long time ago, it was only after the seventeenth century that they began to gain a deeper understanding of the properties of these compounds; pure calcium was not developed by Humphrey David, who named this element until 1808 AD Separated by electrolysis. Calcium compounds have a wide range of industrial applications: as an additional additive in the food industry, as a bleaching agent in the paper industry, as a raw material for cement and insulators, and also in soap making. On the other hand, pure calcium has some unique applications because of its high activity. A small amount of pure calcium is used in the refining of steel, and calcium-lead alloys can also be used as car batteries. The main mineral sources in industry such as limestone and gypsum are widely used in construction (cement raw materials), fertilizers, alkali production, and medical treatment.

Calcium is the most abundant metal element and the fifth most abundant element in the human body. As an electrolyte, calcium ions play an important role in the chemical reactions in organisms and cells: in the process of cell information transmission, calcium ions are part of the second messenger system; as neurotransmitters, they are released by neurons; participate The process of muscle contraction; it is also a cofactor for various enzymes and assists fertilization. In the process of cell polarization, calcium ions are responsible for maintaining the potential difference between the inside and outside of the cell membrane, and play a key role in osteogenesis.

Effects on the human body

 Calcium nutrition

Calcium is an essential mineral nutrient, and all cells need calcium. Calcium ion {\ displaystyle {\ ce {Ca ^ {2 +}}}} {\ displaystyle {\ ce {Ca ^ {2+}}}} is the trigger of many biochemical and physiological processes in organisms, such as Trigger muscle contraction, release hormones, deliver pulses, promote blood clotting, regulate heart rhythm, produce milk, etc. {\ displaystyle {\ ce {Ca ^ {2 +}}}} {\ displaystyle {\ ce {Ca ^ {2+}}}} is especially necessary for various advanced organisms. Modern medical research shows that calcium nutrition is closely related to the functions of more than ten systems such as immune, nerve, endocrine, digestion, circulation, exercise, and reproduction in the body. Basic medical research has confirmed that calcium ion has a huge impact on life, which means that human health cannot be separated from calciumThe content and distribution of the human body

The body's calcium content is about 1 ~ 1.25kg, accounting for 1.5 ~ 2% of body weight,Each kilogram of non-adipose tissue contains about 20-25g of calcium on average. More than 99% of calcium in the body is distributed in bones and teeth, and the remaining less than 1% of calcium is distributed in body fluids and various tissues and organs throughout the body, and is a participant in various physiological activities. This 1% calcium concentration in human tissues and blood must be kept constant, not too high or too low, otherwise it will threaten life safety.

Bone calcium

Calcium is an essential structural component in the formation of bones, teeth and cell walls. The composition of bone calcium is mainly hydroxyapatite crystals, accounting for more than 40% of the bone weight, followed by carbonates, citrates, and a small amount of chloride and fluoride. Bone calcium is extremely important for maintaining the concentration of blood calcium, and is called the "reservoir" of human calcium. When the blood calcium concentration decreases, bone calcium can be quickly mobilized for supplementation. This process is called bone decomposition; otherwise, calcium is "temporarily stored" in the bones.

Tooth calcium

The surface of teeth is enamel (also known as enamel). Except for 5% water, it is composed of inorganic substances (hydroxyapatite and fluoroapatite) embedded in an organic matrix. Among them, hydroxyapatite accounts for more than 98%, the structure is very tight, and it becomes the hardest part of the human body, which is of great significance for teeth to chew and grind food. Hydroxyapatite accounts for about 70% of dentin and about 40% of cementum. Their structure is similar to bone. Once the teeth are formed and calcified, the metabolism is minimized. The intake of vitamins A, C, and D is essential for normal tooth development and calcification. Lack of vitamin A will lead to incomplete calcification of teeth, making it less hard; lack of vitamin C affects the formation of organic matrix in teeth