Role of Hormones in Growth Spurts - An Overview

Introduction

During puberty, the body grows fast. The brain releases special hormones that make changes in the body called puberty. The brain signals the testes in boys to produce testosterone; in girls, it stimulates the production of estrogen and progesterone from the ovaries. These hormones help maturation in the body. Hormones are chemicals moving around the body, turning an infant into a teen and a teen into an adult. Puberty does not occur at the same time in everyone, but varies with individual. A growth spurt does not cause any pain. It is merely body’s growth, and happens fast. It lasts for 2 to 3 years.

What Are Growth Spurts?

• Growth is a characteristic feature of living organisms. It includes the size and number of cells that lead to increased height and weight in human beings. It begins in early embryonic life and continues till old age.

• The exponential and marked increase in growth at puberty is called a growth spurt. Growth spurt appears earlier in girls than boys because girls mature earlier than boys.

• The rate of growth of height and weight is greater in girls from 12 to 14 years, and in boys, it is from 14 to 16 years.

• Despite after pubertal growth is completed at 18 years in girls and 20 years in boys, a small growth continues to be there till 30 years of age.

• Growth spurts are sudden growth or sudden physical changes (physical development) in a short period, and it happens at different stages of childhood till they are fully matured. The growth spurts are patterns of growth as people age.

• Each child will grow at their own pace between the ages of 12 to 20. This is when the child has intense growth within a short span of time. The development includes height, weight, and length.

• They last for a few days or weeks. Examples of growth spurts in a baby can be additional feedings to match the growing body’s demands and changes in sleep patterns. In humans, there are two periods of rapid growth, they are:

1. Infancy -First is infancy, and the fetal growth period is partially continued.

2. Late Puberty - Second is at the time of late puberty before the growth stops. It is due to the action of sex hormones and growth hormones.

Which Hormones Are Responsible for Growth Spurts in Girls and Boys?

The hormones responsible for growth spurts are:

• Growth hormones.

• Estrogen.

• Testosterone.

• Progesterone.

They promote rapid pace of growth.

How Do Growth Hormones Affect Growth Spurts?

The anterior lobe of the pituitary gland releases human growth hormone. It promotes growth in children, maintains normal body structure, and helps in the metabolism of adults and children. The daily output of growth hormone in adults or children is 0.2 to 1 mg daily with a half-life of 6 to 20 minutes. Human growth hormone acts on many body parts and promotes growth in children. Even after maturity, the growth hormone helps maintain metabolism and normal body structure. The actions of growth hormones include:

• Stimulation of growth of bone, cartilage, and connective tissue.

• Growth hormone is an anabolic protein hormone. It affects the ribosomal attachment and increases the amino acids transport into the cells from the extracellular fluid.

• Growth hormone is a diabetogenic hormone because it decreases the glucose uptake by the skeletal muscles and adipose tissues and increases blood glucose level.

• It increases the liver output of glucose.

• It has a catabolic effect, i.e. it increases the release of free fatty acids from the adipose tissues.

What Are the Factors Affecting Growth?

The hormonal factors that contribute to growth are:

• Rapid growth during infancy is due to thyroid hormone and growth hormone.

• Spurt growth in puberty is due to growth hormones and androgen.

• The in-between continuous growth is due to growth hormone and thyroid hormone.

• Post puberty, the remnant of life, growth is due to thyroid hormones, androgens, and growth hormones.

How Does Estrogen Influence the Development of Growth Spurts?

Estrogens are steroid hormones that are specifically and rapidly taken up by target organs. They bind specific proteins in the cytoplasm. The bound product rapidly enters the nucleus. It initiates cell replication and protein synthesis via DNA (deoxyribonucleic acid) and RNA (ribonucleic acid). At puberty, estrogen is secreted in larger quantities, causing following changes in the body:

• It promotes the growth of ovaries, uterus, and vaginas in females.

• It is responsible for secondary sexual characteristics in females.

• It promotes growth of internal genitalia (growth of ovaries, uterus, and vagina).

• It promotes growth of external genitalia.

• It lowers plasma cholesterol levels and prevents the development of atherosclerosis.

How Does Estrogen Play a Role in Growth and Development?

The pubertal growth is highly contributed by increased growth hormone and sex steroid hormone. Estrogens play an important role in pubertal development in both boys and girls. Both estrogens and androgens are responsible for an increased female pubertal growth spurt. The high growth velocity is related to high levels of growth hormones, estrogen, and androgens. In boys at peak velocity, testosterone and estrogen get increased.

In girls, the combined actions of growth hormone, estradiol, and androgens play a role in a pubertal growth spurt. In boys, the growth spurt is due to growth hormones, testosterone, and estrogen. Due to these hormones, there is an increased bone maturation and mineralization with an increase in height velocity.

It is responsible for female secondary sexual characteristics like the development of breasts, endometrium, and menstrual cycle regulation.

How Does Testosterone Affect Growth Spurts?

Testosterone is produced by gonads by the testes in men and ovaries in women. During normal adolescent development in males, testosterone induces a growth spurt by increasing the growth hormone through the increased amplitude of growth hormone peaks. The increased testosterone in boys causes changes like deeper voices, bigger muscles, and facial hair. It promotes the production of sperm from the testes, and it is also important for bone health. It is the hormone responsible for the increase of muscle mass in males. Both growth hormone and testosterone produce synergistic effects on the growth and development of an individual. Both hormones are involved in the body's protein metabolism, which ultimately affects growth.

What Are the Actions of Progesterone on Growth Spurts?

• The ovaries, placenta, and adrenal glands produce progesterone. The action of progesterone initiates synthesis of new mRNA (messenger RNA necessary for the production of protein).

• It promotes the growth of lobules and alveoli tissues in breasts.

• Progesterone stabilizes the body for menstrual cycles and prepares the body for pregnancy.

• Progesterone prepares the body for possible fertilization.

• It prepares the uterus for a fertilized egg to implant.

• After conception, progesterone supports the endometrium for pregnancy.

Conclusion

Poor nutrition can hinder growth spurts. Studies have found a link between proper diet and improved learning. A child's growth is divided into infancy, preschool, middle childhood, and adolescence. In all stages of life, growth is influenced by hormones. Human beings differ from one another, so growth doesn't happen the same way and at the same time for everyone. It is important to monitor puberty and growth in children because it is essential to their reproductive development.