What is the significance of blood in human life?

1) transport of substances (nutrient and unnecessary) and gases (oxygen and carbon dioxide);
2) protective (due to white blood cells (including lymphocytes), antibodies);
3) regulatory (participates in the humoral regulation of processes);
4) thermoregulatory (participates in maintaining a constant body temperature).

Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.