Page 1 - 2.Lesson Notes-secondary sexual characters (2)

SAI International School
Subject- Biology, Class-VIII
Chapter- Reaching the age of adolescence
Subtopic- Secondary sexual characters
-Role of hormones in initiating reproductive functions
Module- 21
Lesson Notes

Secondary sexual characters

 At puberty, some changes occur in both males and females that distinguish them
from each other.
 The features that develop in them are called Secondary Sexual Characters.

Secondary sexual characters in boys

 They grow moustaches and beards.
 They develop pubic hair, hair on their underarms, and on their chest.
 The reproductive organ in male- testes produces gametes sperms.
 The male hormone (testosterone) begins to release by the testes.

Secondary sexual characters in girls

 The reproductive organ in female- ovary produces gametes (ova).
 In girls, breasts begin to develop at puberty.
 Milk secreting glands called mammary glands also develop inside the breast.
 They develop pubic hair, hair on their underarms.
 The female hormone (estrogen) begins to release by the ovaries
 The changes which occur at adolescence are controlled by hormones.

What are hormones?

 Hormones are the chemicals that control certain mechanism in our body secreted
by endocrine glands, such as, pituitary gland which is present in brain also
known as master gland.
 These chemical substances are responsible for changes in the human body at
the time of puberty.
 The male hormone, or testosterone, begins to be released by the testes at the
onset of puberty.
 The female hormone, or estrogen, begins to be released by the ovaries at the
onset of puberty.