Elements that account for less than one tenth of the total weight of human body, such as iron, zinc, copper, manganese, chromium, selenium, molybdenum, cobalt and fluorine, are called trace elements (iron is also called semi-trace elements). The content of trace elements in human body is really negligible. For example, zinc only accounts for 33 parts per million of the total weight of human body. Iron is only 60 parts per million.
1990 FAO/IAEA/ who expert Committee redefined the definition of essential trace elements and divided them into three categories according to their biological functions:
(1) Eight essential trace elements such as iodine, zinc, selenium, copper, molybdenum, chromium, cobalt and iron.
(2) The elements that may be necessary for human body are manganese, silicon, boron, vanadium and nickel in ***5.
(3) Seven elements are potentially toxic, but may have essential functions for human body at low doses, including fluorine, lead, cadmium, mercury, arsenic, aluminum and tin.
Extended data:
People are composed of elements, and 90 elements are detected. There are 74 elements in serum, 48 elements in brain, 49 elements in heart, 50 elements in liver and 18 elements in thymus.
Element is the most basic unit of human body. Scientific research has proved that the abundance of elements in the crust and seawater determines the abundance of elements in the human body, and the unbalanced distribution of environmental elements is the root cause of human endemic diseases. Humans are heterotrophs, and they get nutrients from the environment through the food chain.
The birth and death of human beings are all related to the balance of elements in the body, so the study of "elements and health" came into being. "Elemental medicine" is a discipline based on atomic and molecular biology and centered on element balance, which is engaged in research, observation and solution of human health problems.
The distribution of elements in the human body is regular, and they have been doing orderly movements. The content of elements in various zang-fu organs and fu-organs is specific, that is, "the element is the meridian tropism".
The content of elements in life is less than one millionth, which is called trace elements. Trace elements in life have the following characteristics:
1. Relativity The same element can be used as a constant element in one discipline, but it can be used as a trace element in another discipline. For example, hydrogen is the main element in life chemistry, but it is often studied as a trace element in material science.
2. Low concentration elements are trace in any living body and must obey Henry's law of dilute solution and Nestor's law of distribution.
3. Universality Universality means that there is no absolutely pure substance in nature.
4. Although the abundance of important elements in all research systems is low, they have extremely important specific effects.
5. Relevance Relevance means not only considering their individual behaviors, but also discussing their interrelationships.
References:
Baidu encyclopedia-trace elements