Endocrine System

It is the network of glands that secrete hormones that regulate many bodily functions.

Hormones:

They are those chemical substances secreted by endocrine glands and heterocrine glands. They are called chemical messengers because hormones carry message of one organ to another organ in the form of chemical signals.

Endocrine Glands

1. Pituitary gland:
   It lies inside the brain box below the cerebrum. Its size is of the pea. It is also called master gland because it controls all the other endocrine glands. Those hormones that control other glands are called stimulating hormone. Other than stimulating hormone it also produces growth hormone (which is mostly produced when we sleep at night) which help us to grow (that is why children at growing phase must get proper good sleep).
2. Thyroid gland:
   This gland is located in front of the trachea (windpipe). It produces thyroxin under the influence of thyroid stimulating hormone (TSH) produced by pituitary. For the production of thyroxin iodine is needed. So, if there is low iodine in our food we suffer from goiter i.e. enlargement of thyroid gland leading to hypothyroidism.
3. Parathyroid Gland:
   There are four parathyroid glands present just behind the thyroid gland. The hormone produced by parathyroid is parathormone which controls the calcium level in blood.
4. Pancreas:
   This is a mixed gland. It produces both hormones and enzymes. The hormone produced by pancreas is insulin and glucagon. They are antagonistic in nature. That means one does exactly opposite of the other. Insulin increases blood sugar level whereas glucagon decreases blood sugar level.
5. Adrenal Gland:
   There are two adrenal glands located just above the kidneys. That is why they are also called suprarenal glands. They produce various hormones (aldosterone, cortisol, epinephrine, nor-epinephrine etc.). These hormones are necessary for various body functions such as regulation of blood pressure, release of energy and many more.
6. Testis and Ovary:
   There are two testes in male and two ovaries in females. They secrete sex hormones required for sexual maturity. They are controlled by pituitary through Follicle Stimulating Hormone (FSH) and Luteinizing Hormone (LH).