The Bio Brief

 When Does Reproductive Life Begin?

Adolescents become capable of reproduction when:

• Testes start producing sperms (in boys)
• Ovaries start producing ova/eggs (in girls)

 This usually begins at puberty.

 Duration of Reproductive Life

 In Males

• Sperm production continues for a much longer time
• May continue into old age (though it may slow down)

 In Females

• Reproductive phase begins at puberty (10–12 years)
• Usually lasts till 45–50 years

 So yes —
A woman’s reproductive life lasts from menarche to menopause.

 What Happens in the Female Reproductive Cycle?

After puberty:

• One ovum (egg) matures about every 28–30 days
• The uterus prepares to receive a fertilised egg

Let’s see the steps.

 Menstrual Cycle Flow Chart

Egg matures in ovary
        ↓
Egg is released (ovulation)
        ↓
Uterus wall thickens
        ↓
IF fertilisation occurs → Pregnancy begins
        ↓
IF fertilisation does NOT occur
        ↓
Uterus lining breaks down
        ↓
Menstruation (bleeding)
        ↓
Cycle repeats (~28–30 days)

 Menstruation

If the egg is not fertilised:

• The egg breaks down
• Thickened uterine lining sheds
• Blood and tissue flow out through the vagina

This monthly bleeding is called menstruation.

 Key Facts

• Occurs every 28–30 days
• First menstruation = Menarche
• Stoppage of menstruation = Menopause

 Important Terms

 Menarche

• First menstrual flow
• Occurs at puberty

 Menopause

• Permanent stoppage of menstruation
• Occurs around 45–50 years

 Irregular Periods at First

• In the beginning, menstrual cycles may be irregular
• After some time, they usually become regular

 This is normal — no need to worry.

 Hormonal Control

The menstrual cycle is controlled by hormones.

They regulate:

• Maturation of egg
• Release of egg
• Thickening of uterus
• Breakdown of uterine lining

 Hormonal Control of Menstrual Cycle

Hormones released
        ↓
Egg matures in ovary
        ↓
Egg released
        ↓
Uterus prepares for pregnancy
        ↓
No fertilisation → Menstruation

 What If Fertilisation Occurs?

If sperm meets the egg:

• Fertilised egg divides
• Gets embedded in uterus
• Pregnancy begins
• Menstruation stops during pregnancy

 Quick Revision

 Reproductive life begins at puberty
In females it lasts from menarche to menopause
 One egg releases every 28–30 days
 If not fertilised → menstruation occurs
 Menstrual cycle is hormone-controlled
 Early cycles may be irregular
 Males have a longer reproductive period