A cell is an elementary structural unit of all organisms (except viruses).
In the cell, the metabolism and energy take place, and the cell also allows you to respond to the actions of certain stimuli (irritability). Nerve, muscle and secretory cells are excitable as a result of a strong stimulus (excitability). Nerve and muscle cells form and conduct electrical impulses (conduction). Muscle cells perform motor functions in the body (contractility). Secretory cells synthesize and secrete a secret – a waste product. Somatic cells provide the growth and vitality of the organism (the ability to reproduce itself).
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.