Puberty

Explained

Puberty, and the hormones that run it

Puberty is the period during which the reproductive system becomes mature and the body develops its secondary sexual characteristics. It is triggered by hormones, and its timing varies widely between individuals, typically starting somewhere between about 10 and 14 years of age.

The distinction the specification wants is between primary and secondary sexual characteristics. Primary characteristics are the reproductive organs themselves, present from birth. Secondary characteristics are the features that develop later, at puberty, under the influence of the sex hormones.

What starts it

The pituitary gland in the brain begins releasing FSH and LH, which act on the ovaries or the testes. Those organs then produce the sex hormones, and it is the sex hormones that cause the visible changes.

So the chain runs brain, then gonad, then body. The same arrangement runs the menstrual cycle later, which is why the two topics share their hormones.

Oestrogen in females

Oestrogen is produced by the ovaries. It causes the breasts to develop, the hips to widen, and pubic and underarm hair to grow.

It also starts the menstrual cycle, and the first period is called the menarche. The ovaries begin releasing eggs, which they have carried since before birth, one at a time from puberty onwards.

Testosterone in males

Testosterone is produced by the testes. It causes the voice to deepen as the larynx grows, facial, body and pubic hair to develop, the shoulders to broaden and muscle to develop.

It also starts sperm production in the testes, which then continues throughout life rather than being released in a monthly cycle.

What both share

Both sexes experience a growth spurt, an increase in body hair and changes in body shape and in emotions. Only the details differ, so a question asking for a difference wants a specific characteristic rather than the general idea that the body changes.

The single most examined point is which hormone goes with which sex, and where it is made. Oestrogen from the ovaries in females; testosterone from the testes in males. Both are made in small quantities in the other sex too, but for exam purposes each belongs to one.

Puberty and the topics either side of it

This page sits between two others, and seeing the connection saves learning three sets of facts.

Before it, the reproductive organs are the primary characteristics, present but not yet functioning.

After it, the menstrual cycle takes over in females, run by the same pituitary hormones that started puberty and by oestrogen, joined now by progesterone. The hormone that caused the breasts to develop is the same one that rebuilds the uterus lining each month.

Puberty, then, is not a separate topic with its own hormones. It is the moment the reproductive system is switched on, and everything after it uses the machinery that was switched on here.