This document discusses biogenic elements and their importance in living organisms. It covers the following key points: 1. Biogenic elements are chemical elements that are always present in living organisms and perform biological functions. Only 81 of the 118 known elements are found in organisms. 2. Endemic diseases are caused by excess or lack of certain biogenic or toxic elements due to unusual concentrations in an organism's diet and are spread only in certain territories. 3. Biogenic elements are classified and their biological importance is discussed, along with the use of their compounds in medicine. The effects of toxic metals on human health and the medical use of radioactive elements are also addressed.

1. Macro- and microelements:
biological role, medical applying

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Questions of the lesson:
1. Biogenic elemets. Classification of biogenic elements.
2. Endemic diseases: causes, methods of prevention.
3. Biogenic s-, p-, d- elements, their biological importance and use of
their compounds in medicine..
4. Types of chemical bonds and their main characteristics. Van der
Waals forces.
5. Characteristics of the structure of the electron structure of atoms
and ions, their influence on the types of bonds formed.
6. The relationship between the structure of molecules and the
biological activity of substances.
7. Effect of toxic metals on human health.
8. Radioactive elements used in medicine. Biological effect of
radiation.

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Biogenic elements are those
chemical elements which are
always presentin living
organisms and perform certain
biological functions.

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BIOGENIC ELEMENTS
From 118 elements known to exist in Nature, 81 elements
are found in organisms of animals. There are four criterions
that must be satisfied for a biogenic element:
- It must be present permanentlyin the organisms of the
same species in the same quantities;
- The concentration of an element is different in different
tissues and organs: some tissues are enriched by a given
element;
- Synthetic ration without a given element causes specific
symptoms of insufficiency by the way of biochemical
changes in tissues;
- These symptoms disappear after the return of a given
element into the ration

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•Microelements become dangerous at increased
concentrations when they demonstrate their
toxic effects
•Interestingly, a toxic element arsenic is a
known (since 19thcentury) biostimulator at low
concentrations
•There are no toxic elements, but there are toxic
concentrations

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Endemic disease is a disease
caused by the excess or the lack
of certain biogenic or toxic
elements because of their unusual
concentrations in the ration.
Endemic disease is spread only in
the certain territory.

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