Page 1 - 2.L.N-Reproductive phase of life in humans

SAI International School
Subject- Biology, Class-VIII
Chapter- Reaching the age of adolescence
Subtopic- Reproductive phase of life in humans-
Sex determination
Module- 22
Lesson Notes

Reproductive phase of life in Humans

(i)Menstrual cycle in females

 When girls reach the age of adolescence, they enter the age when they are
capable of reproduction.
 The reproductive age in girls begins right form the age of 10 to 12 years and
ends at the age of 45 to 50 years.
 At the onset of puberty, the ovaries in girls startto mature. Every month, one
ovum gets matured and then gets released by the ovaries.This procedure
happens once in 28 to 30 days approximately.
 At this time of month, the uterine wall becomes thick to receive the mature egg. If
the egg gets fertilized and begins to develop, it leads to pregnancy.
 But if fertilization does not occur, then the released egg and thick lining of uterus
along with blood gets shed off through the vagina in females.
 This leads to bleeding in women at a specific period of month (once in about 28-
30 days) and is called menstruation.

The first menstrual flow in girls once they reach the age of adolescence is called
menarche.

The stoppage of menstrual flow at the age of 45-50 years in girls is called menopause