Endokrines

Endokrines refers to the endocrine system, the body's collection of glands and tissues that produce hormones and secrete them into the bloodstream. It coordinates physiological processes through chemical signaling rather than direct neural transmission and acts in concert with the nervous and immune systems.

The major endocrine glands include the hypothalamus, pituitary gland, thyroid, parathyroids, adrenal glands, pancreas (islets of Langerhans), gonads (ovaries and testes), pineal gland, and thymus, among others. Neuroendocrine cells in the brain integrate neuronal signals with hormonal output, linking the nervous system to endocrine control.

Hormones are chemical messengers released into the bloodstream that travel to specific target cells or organs, where they bind to receptors to regulate metabolism, growth and development, reproduction, water and electrolyte balance, and responses to stress. Hormone release is frequently controlled by feedback loops, especially the hypothalamic-pituitary axis, which coordinates multiple hormonal pathways.

Endocrine tissue contrasts with exocrine tissue, which releases substances through ducts to surfaces or body cavities. Many organs perform dual roles (for example, the pancreas has endocrine islets and exocrine ducts). Disturbances in endocrine function can lead to disorders such as diabetes mellitus, hypothyroidism, and Cushing’s syndrome, reflecting the system’s central role in homeostasis and adaptation.

The term endocrine derives from Greek words meaning within and to secrete. The concept was formalized in the early 20th century, with the idea of hormones and hormonal regulation attributed to researchers such as Bayliss and Starling.