The bones start to form from the third month of intrauterine development of the child. The process of ossification of the man skeleton lasts througho

Bone growth and development

The bones start to form from the third month of intrauterine development of the child. The process of ossification of the man skeleton lasts throughout his life. Bones grow unevenly especially in length.

The greatest bone growth in length is observed in the first two years of life a little less — up to 9-10 years. Bone growth accelerates during puberty: girls 12-13, boys 13-14 years. During this period they can grow up to 6-10 cm per year. Bones grow up to age of 20-25 years; in thickness — at the expense of the periosteum, and in length — at the expense of the cartilage.

Bone growth is regulated by growth hormone, that is produced by the pituitary gland, and depends on the exchange of minerals, primarily calcium and phosphorus, and vitamins D and A. Due to a lack of vitamin D children suffer from rickets. Actively working skeletal muscles stimulate bone growth, to which they are attached.

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Questions:
  • Explain how the chemical composition of bone is associated with their function and the age of the person.

  • How do physical labor and sport affect the bone structure?