Development of Secondary Sexual Characteristics

Section 1 of 8What and why

Secondary sexual characteristics

• Secondary sexual characteristics These are the changes during puberty that mark the body's development towards adulthood and the ability to reproduce.
• They are different from the primary sexual characteristics, the reproductive organs present from birth.

Hormone control

• Hormone control Puberty is triggered when hormones are released in larger amounts.
  • The key sex hormone in females is oestrogen and in males is testosterone.

Typical timing

• Typical timing Puberty usually starts in early adolescence, though the exact age varies between individuals.

Section 2 of 8Changes in females (oestrogen)

Oestrogen

Breasts

• Breasts The breasts develop.

Body hair

• Body hair Hair grows under the arms and in the pubic region.

Hips

• Hips The hips become wider.

Menstrual cycle

• Menstrual cycle Ovulation and periods begin.

Section 3 of 8Changes in males (testosterone)

Testosterone

Sex organs

• Sex organs The testes and penis grow.

Sperm

• Sperm The testes start producing sperm.

Hair

• Hair Facial and body hair grow.

Voice

• Voice The voice breaks and becomes deeper.

Muscles

• Muscles Muscles develop and grow stronger.

Section 4 of 8Comparison

Feature	Females	Males
Hormone	Oestrogen	Testosterone
Made in	Ovaries	Testes
Gamete production starts	Egg release and periods	Sperm production
Body shape	Wider hips, breast development	Muscle growth, broader build
Shared changes	Pubic and underarm hair; growth of sex organs; emotional changes	Pubic and underarm hair; growth of sex organs; emotional changes

Section 5 of 8How the hormones act

1Release

• Release At the start of puberty the testes or ovaries begin to make much larger amounts of their sex hormone.

2Transport

• Transport The hormone is carried around the body in the bloodstream to every tissue.

3Target tissues respond

• Target tissues respond Only cells with the right receptors respond, for example breast tissue to oestrogen or muscle and vocal cords to testosterone.

4Visible change

• Visible change Over a few years the changes build up, so a child gradually develops the body of an adult capable of reproduction.

Section 6 of 8Emotional changes

1

Higher hormone levels affect the brain as well as the body.

2

Both sexes may feel increased interest in sex.

3

Both may experience mood swings.

4

These changes are a normal part of puberty and settle as hormone levels become steadier.

Section 7 of 8Key terms

Term	Meaning
Puberty	The stage of life when the body becomes able to reproduce.
Secondary sexual characteristics	Body changes at puberty controlled by sex hormones.
Oestrogen	The main female sex hormone, made in the ovaries.
Testosterone	The main male sex hormone, made in the testes.
Hormone	A chemical messenger carried in the blood.

Section 8 of 8Exam technique

1

Attributing female changes to testosterone or male changes to oestrogen.

2

Listing the testes making sperm as a secondary characteristic only; it is a result of puberty hormones turning on gamete production.

3

Thinking that only girls grow underarm hair; both sexes do.

4

Forgetting that hormones also cause emotional changes such as mood swings.