Hormones in Human Reproduction - Puberty and Hormones (GCSE Biology)

Puberty and Hormones

Reproductive Hormones

Reproductive hormones are essential for reproduction.

The process of reproduction is completely driven by hormones. At different ages, different hormones have different targets and effects. They are required for growth, attaining puberty and for fertility.

Reproductive Hormones during Adolescence

Changes During Adolescence

Reproductive hormones are released during adolescence, and they lead to many changes.

One of the most important periods of life (biologically) occurs during adolescence (puberty). As children turn 11 or 12, their bodies begin changing and maturing, in order to cope with the demands of adulthood.

During puberty, reproductive hormones lead to two key changes:

• Secondary sex characteristics – during adolescence, the release of reproductive hormones begins in boys and girls. These hormones lead to the development of secondary sex characteristics, which are factors that can be used to differentiate between girls and boys, but are not directly involved in reproduction – e.g. a beard for a boy.
• Production of sex cells – during adolescence, the reproductive hormones also stimulate production of sex cells – sperm in males, and eggs in females. Therefore both males and females develop the ability to make sex cells, which are needed for reproduction.

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Testosterone in Males

We will now look at the changes in males caused by the reproductive hormone testosterone.

Testosterone is the main reproductive hormone for males. It is produced in the Leydig cells of the the testes. During puberty, it causes many changes in males:

• Hair growth increases on face, body, pubis and underarms
• Muscle growth increases
• Voice deepens and breaks
• Sperm production begins
• Penis and testes develop

Testosterone stimulates the production of sperm in males. This is key because during puberty in females oestrogen leads to the formation of eggs. Therefore both males and females develop the ability to make sex cells, which are needed for reproduction.

Oestrogen in Females

We will now look at the changes in females caused by the reproductive hormone oestrogen.

Oestrogen is the main reproductive hormone of females. It is produced in small amounts in males. It is produced in the ovaries of females. During puberty, it causes many changes in females:

• Underarm and pubic hair growth increases
• Sexual organs develop
• Breasts form
• Hips widen
• Voice gets slightly deeper

Oestrogen also causes ovulation. Ovulation is the release of an egg from the ovaries. During puberty, eggs begin to mature. This means that the eggs can take part in a 28 day process, at the end of which, one egg is released from the ovary into the fallopian tube. This process is called the menstrual cycle, and we will learn about this more in the next tutorial.