Growth hormone is one of the important hormones secreted by the anterior pituitary gland in the brain. As the name indicates, it promotes the growth of the body.
It secreted under the influence of hormones secreted by the hypothalamus. The growth hormones releasing hormone (GHRH) stimulates the pituitary to release growth hormone. While the growth hormone release inhibiting hormone (GHRIH) inhibits the secretion of growth hormone from the pituitary.
This secretion of growth hormone is also inhibited by the somatostatin which is secreted by pancreatic islets.
Physiology of Human Growth Hormone
GH promotes the growth of a person during his early life. It is believed that the height of a person grows until 18 years and ceases to grow thereafter.
GH increases protein deposition by different mechanisms.
1. It enhances the growth of all the cells and tissues of the body. During childhood and adolescence, the growth hormone promotes the growth of cells and tissue of bone and skeletal muscles prominently.
It promotes the cell size, increases mitosis and differentiation of bone and muscle cells.
Once adolescence is over, it maintains the mass of cells and tissues of bones and muscles for the rest of the life.
It also regulates the metabolism in the organs like the intestine, liver, and pancreas. It promotes growth and repair, breakdown of fats and increases blood glucose levels.
2. It increases the rate of protein synthesis by
a) Enhances the DNA transcription to form mRNA responsible for protein formation.
b) Increase the translocation of RNA for enhanced protein synthesis.
C) Enhanced amino acids transport across the cell membrane.
d) Decreases of protein catabolism by mobilization of fatty acids required of gluconeogenesis. Thus amino acids are spared.
3. Increase fat metabolism and thereby lean body mass.
GH promotes the release of fatty acids from adipose tissue. Then it also enhances the utilization of fatty acid for energy generation. Thus the with its ability to enhance fat metabolism and protein deposition, it causes lean body mass.
However, it is effective in height growth until a particular age of 18. This height growth stops at around 18 years of age due to the growth of pubic symphysis. During this phase, the epiphysis of the long bones unites with the shafts. Once done no further rise in height is possible.
So growth in height is freely possible till this age of 18 to 19. Thereafter though the growth hormone is secreted, there is no growth in height. Instead, the body tissue mass grows.
So the best chance of height growth by this hormone is before the end of height growth.
Can one grow taller after puberty? Puberty is physical maturation around 13-15 years for both girls and boys. And the age till which body grows in height is 18 years. So one has chances of growth for 4-5years after puberty.