The UPSC mains GS-3 paper syllabus has various subjects like Economics, Science and Technology. Science and technology in UPSC is mostly concerned with current Affairs. but it is necessary to understand the basics of science. Human Body consists of some of the most complex systems.


  • What is Endocrine system
  • Endocrine system organs


  • The endocrine system is a network of glands and organs located throughout the body. It’s similar to the nervous system in that it plays a vital role in controlling and regulating many of the body’s functions.
  • However, while the nervous system uses nerve impulses and neurotransmitters for communication, the endocrine system uses chemical messengers called hormones.
  • Keep reading to discover more about the endocrine system, what it does, and the hormones it produces.


  1. The endocrine system is made up of a complex network of glands, which are organs that secrete substances.
  2. The glands of the endocrine system are where hormones are produced, stored, and released. Each gland produces one or more hormones, which go on to target specific organs and tissues in the body.
  3. The endocrine system also helps in coordinating the activities of our body. The endocrine glands present in our body are the pineal gland, hypothalamus gland, pituitary gland, thyroid gland, parathyroid gland, thymus, pancreas, adrenal gland, testes, and ovaries. The nervous system controls the working of endocrine glands. The hormones act as a messenger between the nervous system and organs of the body.
  4. Hypothalamus and pituitary gland are main centres for the coordination of the nervous system and endocrine system. The hypothalamus helps in collecting information from the regions of the brain and from blood vessels passing through it. The information is then passed on to the pituitary gland which by its secretions regulates the activities of all other endocrine glands. In the human body, hormones help in growth, metabolic activities and reproduction.

The glands of the endocrine system in details:


This gland is present in the brain and produces releasing hormone and inhibitory hormone. Hypothalamus regulates the secretions of hormones from the pituitary gland.

Pituitary Gland

This gland is present just below the brain and secretes a number of hormones. One of the hormones secreted by the pituitary gland is growth hormone. This growth hormone controls the development of bones and muscles. A person having a deficiency of growth hormone becomes very short and the person having too much growth hormone becomes very tall.

Thyroid Gland

The thyroid gland is attached to the windpipe and makes a hormone called thyroxin which contains iodine. The function of this hormone is to control the rate of metabolism of carbohydrates, fats, and proteins in the body. The deficiency of iodine in the diet can cause a deficiency of thyroxin hormone in the body. This causes a disease called a goitre.

Parathyroid Gland

There are four parathyroid glands that are embedded in the thyroid gland. The parathyroid gland secretes a hormone called parathormone which helps to regulate calcium and phosphate levels in the blood.

Thymus Gland

This gland is present in the lower part of the neck and upper part of the chest. Thymus gland secretes thymus hormone which helps in the development of the immune system of the body.


This hormone is present just below the stomach and secretes a hormone called insulin. The function of insulin is to lower the blood sugar level. The deficiency of insulin hormone causes a disease called diabetes. A person having diabetes has large quantities of sugar in the blood.

Adrenal Glands

Adrenal glands are located at the top of two kidneys. These glands secrete an adrenal hormone that regulates heart rate, breathing rate, blood pressure, and carbohydrate metabolism. This hormone is secreted in large amounts when the person is excited or frightened. This gland is also called glands of emergency.


This gland is present only in males and makes male sex hormones called testosterone. The testosterone controls the development of male sex organs and male features such as deeper voice, mustache, beard, etc.


This gland is present in females only and make a female sex hormone called oestrogen and progesterone. Oestrogen helps in controlling the development of female sex organs and female features such as feminine voice, soft skin, and mammary glands. The progesterone hormone controls the uterus changes in the menstrual cycle. It helps in the maintenance of pregnancy.

Feedback Mechanism 

The excess or deficiency of hormones has a harmful effect on our bodies. So in order to control and regulate the production and release of hormones in the body, there is a feedback mechanism that is in-built in our body.



The nervous system is the major controlling, regulatory, and communicating system in the body.

Respiratory System


The respiratory system is the network of organs and tissues that help you breathe. It includes your airways, lungs, and blood vessels


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