Endocrine System and Reproductive Health- Biology Guide for Class 8

Endocrine System and Reproductive Health- Class 8 Science Guide

Information about Endocrine System and Reproductive Health


Endocrine System and Reproductive Health


Class 8


Class 8 Biology

Topics Covered

  • The Endocrine System 
  • Reproductive Health 
  • Nutritional Needs of Adolescents
  • Personal Hygiene

The Endocrine System 

The endocrine system is a system of glands that involve the release of chemicals called hormones.
Endocrine glands are also known as ductless glands as they do not have any ducts of their own; they pour their secretions directly into the blood stream.
The endocrine system regulates metabolism, growth, development and puberty of the body. It also plays a part in controlling mood.
The major glands that make up the human endocrine system include:
  • hypothalamus
  • pituitary
  • thyroid
  • parathyroid
  • adrenals
  • pineal
  • reproductive glands (ovaries and testes).

Pituitary gland

One of the hormones released by the pituitary gland is the growth hormone which regulates the growth and development of the body.

Thyroid gland

  • The thyroid gland releases thyroxine that regulates the metabolic rate of various body functions.
  • If enough thyroxin is not released by the thyroid gland, the thyroid gland may swell up and cause a bulge in the neck region. This diseased condition is called goitre.
  • It usually occurs due to the deficiency of iodine in the diet.


  • Insulin, a hormone released by the pancreas, lowers the blood glucose level.
  • If it is not secreted in sufficient quantities, the person is said to suffer from the disease called diabetes

Adrenal glands

  • The adrenal glands are tiny organs that are located on top of each kidney.
  • They release adrenaline, a hormone which controls the response of the body to stressful situations. 
  • They also release hormones which regulate the mineral levels in the blood.

Role of Hormones in Completing the Life Cycle of Frog and Insects

In a frog, the tadpole (larval stage) hatches from the eggs and passes through various stages to become an adult. This transformation, from a tadpole to a frog, is known as Metamorphosis.
  • The hormone 'thyroxine' produced by the thyroid gland of the frog, is essential to carry out this process of metamorphosis.
  • Iodine is needed for the production of thyroxine. It is made available by the water in which the tadpoles are growing.
  • Insects also undergo metamorphosis, to change from larval to adult forms.
  • This is regulated by the relevant insect hormones, produced by some cells in their brain and endocrine glands, located elsewhere in their body. 

Reproductive Health 

Adolescence is a time of increased growth and development of the body. During this time, a greater need for nutrients coincides with a change in food habits; these, in turn, influence the nutritional needs.

Nutritional Needs of Adolescents

Poor nutrition in adolescence can have adverse health consequences in adulthood. Obesity and excessive fat intake increases the likelihood of being an overweight adult; this can put the individual at risk for cardiovascular diseases and other health problems.
  • Consuming cold drinks and (canned) fruit juices, instead of milk, at this time of rapid growth and bone-building, may lead to osteoporosis and bone fractures during the old age.
  • A diet, heavily dependent on fast food, results in decreased energy, excess fat and a deficiency of calcium, riboflavin, vitamin A, folic acid and fibre.
  • A balanced and healthy diet, during adolescence, promotes proper growth and overall maturity.
  • Calcium and iron are both needed for growth. Vitamin D, which is needed to enable the body to absorb calcium, is often deficient if the diet contains no milk.
  • Once a girl has started menstruating, her need for iron increases. Calcium, magnesium, boron, vitamin D and K, zinc, copper and manganese are all needed to build strong and healthy bones. For this purpose, phosphorus is also required but it is unlikely to be lacking in the diet.
  • Failure to build healthy bones may increase the risk of osteoporosis in later life.
  • Zinc, manganese, chromium and selenium are often low in the diet of teenagers as they tend to eat too much of refined carbohydrates (such as white flour and sugar).
  • Vitamin C can be deficient if sufficient fresh fruits and vegetables are not consumed.
We, thus, realise that it is very important for adolescents to consume a healthy and balanced diet. 

Personal Hygiene

Personal hygiene entails more than just 'being clean'. It includes many practices that help people to stay healthy. Many of the health problems, that adolescents face, are linked to their activities and habits.  Adolescents need to know how to take care of their evolving and changing body.
  • Bathing daily, use of a proper soap, maintaining dental and oral hygience, care of the eyes and ears, and proper grooming, are some of the habits that adolescents need to follow regularly.
  • Both girls and boys need to be aware of the hygienic measures that promote personal hygiene.
  • To avoid infections, girls should take special care of cleanliness during menstruation. 

Physical Exercise

Just like food, physical activity, or exercise is a daily requirement.
  • Scientific evidence indicates that walking, jogging, running and playing games stimulate the growth process and keeps the individual fit. 
  • Exercise also helps in better digestion of food and more efficient elimination of toxins from the body.
  • It improves blood circulation and increases the respiratory efficiency of lungs.
  • Physical activity is also important to combat the stress and strain of adolescence.

Say 'No' to Drugs

'Experimentation' with drugs during adolescence may take place under 'peer pressure. Unfortunately, teenagers often do not see the link between their actions 'today' and resulting consequences of 'tomorrow.
  • Using alcohol and tobacco at a young age increases the risk of using other drugs later.
  • Peer pressures, to pose like an adult and to impress the opposite sex, are some of the reasons that may lead the adolescents to smoke or to take drugs and alcohol.
  • However, such habits affect their health and the adolescents may lose self-confidence and control over themselves. 
The phrase 'Just Say No' is a part of the —'Say No to Drugs'—campaign. This campaign aims at educating people about the harmful effects of drugs and guides them about building effective strategies to stay away from them.
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