Endocrine System:

The endocrine system is the collection of glands that produce hormones that regulate metabolism, growth and development, tissue function, sexual function, reproduction, sleep, and mood, among other things.

The endocrine system is made up of the pituitary gland, thyroid gland, parathyroid glands, adrenal glands, pancreas, ovaries (in females) and testicles (in males), the Mayo Clinic notes.

The word endocrine derives from the Greek words "endo," meaning within, and "crinis," meaning to secrete, according to Health Mentor Online. In general, a gland selects and removes materials from the blood, processes them and secretes the finished chemical product for use somewhere in the body. The endocrine system affects almost every organ and cell in the body, according to the Merck Manual.

Although the hormones circulate throughout the body, each type of hormone is targeted toward certain organs and tissues, the Merck Manual notes. The endocrine system gets some help from organs such as the kidney, liver, heart and gonads, which have secondary endocrine functions. The kidney, for example, secretes hormones such as erythropoietin and renin. 

Milestones in the study of the endocrine system

200 B.C.: The Chinese begin isolating sex and pituitary hormones from human urine and using them for medicinal purposes

1025: In medieval Persia, the writer Avicenna (980-1037) provides a detailed account on diabetes mellitus in "The Canon of Medicine" (c. 1025), describing the abnormal appetite, the collapse of sexual functions and the sweet taste of diabetic urine.

1835: Irish doctor Robert James Graves describes a case of goiter with bulging eyes (exophthalmos). The thyroid condition "Graves' disease" was later named after the doctor.

1902: William Bayliss and Ernest Starling perform an experiment in which they observe that acid instilled into the duodenum (part of the small intestine) causes the pancreas to begin secretion, even after they had removed all nervous connections between the two organs.

1889: Joseph von Mering and Oskar Minkowski observe that surgically removing the pancreas results in an increase of blood sugar, followed by a coma and eventual death.

1921: Otto Loewi in 1921 discovers neurohormones by incubating a frog's heart in a saline bath.

1922: Leonard Thompson, at age 14, is the first person with diabetes to receive insulin. Drugmaker Eli Lilly soon starts mass production of insulin.

Information Taken from: https://www.livescience.com/26496-endocrine-system.html