Adolescence is a stage marked by numerous physical, biological and psychological changes, which will greatly influence the way adolescents think, grow and relate.

In this article we will focus on the biological changes in adolescence , which have an enormous weight in sexual maturity, through the formation of secondary sexual characteristics, mainly. We will see what happens in the body (and also in the mind) of boys and girls who enter and go through this complex and fascinating stage.

Biological Changes in Adolescence: An Overview

Adolescence is a stage of life from the onset of puberty (the end of childhood) to the beginning of adulthood. At the end of adolescence, and well into adulthood, at the biological level the development of the body is already complete.

The biological changes in adolescence are multiple, as well as the psychological and, in many cases, social changes. This stage, also called, in colloquial language, “the age of the turkey”, is characterized by a great hormonal movement, among other processes , and by the well-known “stretch” that occurs in the adolescent’s body.

Furthermore, on a psychological level, the adolescent is in the middle of a process of configuration of the personality , which is being defined.

Importance of the hypothalamus-pituitary axis

To understand the biological changes in adolescence, we must know the hypothalamic-pituitary axis. This is located in the central nervous system, and is in charge of secreting different types of hormones: gonadotropins, luteinizing hormone (LH) and sex hormones .

The sex hormones are mainly estradiol for girls and testosterone for boys. Thus, the functioning of the hypothalamus-pituitary axis will mark the biological changes in adolescence.

Hormones and “pull”

At this stage, there is a significant secretion of sex hormones. These hormones promote growth and development in the adolescent, since they influence the secretion of growth hormone. Specifically, what is produced is the well-known “growth spurt”. More or less, the “growth spurt” ends at the age of 16 in girls and 18 in boys . Once this process has concluded, the remaining size is usually the one that will last almost all of one’s life.

But what exactly are the biological changes in adolescence that explain the growth spurt, as well as other processes? Let’s look at them in detail.

Puberty

Puberty is the first stage of adolescence (early or initial adolescence) . It is characterised by the appearance of noticeable changes in the body of the boy or girl.

In terms of physical development, in girls the breast button appears, and in boys, it increases the volume of the testicles. In boys, moreover, the scrotum is thinned and acquires a finer appearance.

1. Secondary sexual characteristics

In terms of the development of secondary sexual characteristics, we can differentiate, in boys and girls, the following biological changes in adolescence

1.1. Children

Between 9 and 10 years of age there is an increase in the testicles, as we have seen, as well as a decrease in the scrotum. The scrotum also takes on a dark colouring. On the other hand, the penis grows in size.

1. 2. Girls

In girls, between the ages of 8 and 10, the areola of the breast button becomes prominent. Later, 6 months to 1 year after this process begins, the first period (also called menarche) appears.

Sexual maturity

The biological changes in adolescence, as we see, focus on the sexual area l (which in turn, affect many others). In this way, the sexual maturity of the adolescent is also consolidated and established. What changes, concretely, occur in this sense?

1. Children

We can differentiate up to five stages in the sexual maturity of boys, during their adolescence.

In stage I, called pre-pubertal, boys do not yet have secondary sexual characteristics . In stage II, public hair appears, which is long and fine. The texture of the scrotum begins to change, and the size of the penis and testicles increases.

In stage III, the pubic hair begins to curl. The testicles and scrotum continue to grow. In stage IV, the hair becomes increasingly curly and coarse (although it does not look like adult hair). The penis and testicles are still growing. The glans also becomes larger, and the scrotum becomes more pigmented. Finally, in stage V, the hair is like adult hair and extends to the inner thighs. The penis and testicles also look like an adult.

2. Girls

In the case of girls, up to five stages can also be differentiated in relation to their sexual maturation.

In stage I (pre-pubertal), secondary sexual characteristics have not yet formed. In stage II, fine, hypopigmented pubic hair appears. The breast bud appears, with an increase in the areola (which protrudes). In stage III, the pubic hair curls and increases in quantity; its pigmentation also increases. The breasts also increase in size, that is, they begin to grow.

In stage IV, the hair becomes increasingly curly and thick. The areola forms a small elevation above the breast. The breasts continue to increase in size.

Finally, the biological changes in adolescence, at the sexual level in girls, in stage V, are: a curly and abundant hair; on the mount of Venus, the hair forms a triangle; the lips also increase, the breasts mature and the areola forms part of its contour, and the nipple protrudes.

Other changes of adolescence

The biological changes in adolescence are very important, because they influence the personality of the adolescent, as well as his way of thinking, growing up, relating, seeing himself …

That is why we cannot stay only with the biological changes, since, at a psychological level, there are also many changes that should be known, and that are strongly interrelated with the first ones. Let’s know some of the most important:

Interest in sexuality

It is a known fact; in adolescence interest in sex and sexuality is born and grows . The first sexual contacts, touches, ejaculations begin… All this, logically, is influenced by the biological changes in adolescence, which make sexual maturity possible.

2. Thought and Social Relations

Abstract thinking is gradually being consolidated. On the other hand, on a social level, there is an increasing separation from the family, and social relations (or at least, interest in them) are increasing.

At this stage social groups become very important for the configuration of the personality of each one, which is in full process. The adolescent is in search of himself, of what he is, of what he likes, of how he feels… In turn, it can be a very complicated stage in this sense.

3. Other biological changes

There are also changes in the voice, which becomes deeper (especially in boys), the size of the respiratory organs (lung and larynx) increases, there is an excess of activity of the sebaceous glands… The latter is what produces acne, for example.

Bibliographic references:

  • Christie, D. & Viner, R. (2005). Adolescent development. British Medical Journal, 330(7486):301-304.
  • Mafla, A.C. (2008). Adolescence: bio-psycho-social changes and oral health. Medical Colombia, 39(1): 41-57.
  • Rahola, R., Garde, T.M., Cozzetti, E. et al. (2002). Adolescence: biological, psychological and social considerations. Manual de Salud Reproductiva en la Adolescencia: