Page 10 - Health & Physical edu- 8

h. Gonads

This gland consists of two other glands specific to males and females. They are:
ovaries in females and testes in males. They are heterocrine glands which secrete
hormone and gametes.

i. Ovary

This gland is in females only. Two of this gland remains on the right and left sides
of uterus. This gland secretes the hormones named oestrogen and progesterone.
Oestrogen enlarges size of breasts, grows pubic hair, and activates ovaries to produce
ova. Progesterone creates favourable conditions for fertilized ova to be alive. It assists
the zygote to grow and activate breast to produce milk. This hormone is responsible
for menstruation in females.

ii. Testis

This gland is in males only and has two small parts. It produces hormone called
testosterone. Due to this hormone, beard and other hairs grow in males. Similarly,
this hormone is responsible for the development of hoarse sound in males and
increment of size of penis. This hormone activates the testis to produce sperms.

The Nervous System

The nervous system controls and regulates all the other systems as well as external

and internal activities in our body. This system is also known as a mater system. In
the nervous sytem, there are neurons and nerve fibres. This system can be divided
into three parts as mentioned below.

Cell body
Cell nucleus
axon

Nucleus fibers

6 Health & Physical Education, Class-8