Comprehensive Overview of the Human Endocrine System

Endocrine System

Consists of endocrine glands and various organs that release chemical messengers into the internal environment.

Endocrinology

The scientific field concerned with the structure and functions of endocrine glands, and the diagnosis and treatment of disorders related to the endocrine system.

Exocrine Glands

Glands that possess a system of ducts that lead their secretions to the exterior of the body.

Endocrine Glands

Glands that lack ducts; their secretions pass directly into the bloodstream.

Hypothalamus

Acts as the master regulator; it manages the anterior pituitary and synthesizes hormones for the posterior pituitary.

Posterior Pituitary Hormones

Includes oxytocin, which stimulates uterine contractions and milk release, and antidiuretic hormone (ADH), which promotes water retention.

Anterior Pituitary

Regulated by hypothalamic releasing and inhibiting hormones, it secretes tropic and nontropic hormones.

Growth Hormone (GH)

Stimulates growth and metabolic functions; targets the liver, muscles, and other tissues.

Thyroid Gland Hormones

Includes T3 and T4 that stimulate metabolic processes, and calcitonin that lowers blood calcium levels.

Insulin

Lowers blood glucose levels; regulated by glucose levels in blood.

Glucagon

Raises blood glucose levels; regulated by glucose levels in blood.

Epinephrine and Norepinephrine

Hormones from the adrenal medulla that raise blood glucose levels and increase metabolic activities.

Androgens

Steroid hormones from testes that support sperm formation and male secondary sex characteristics.

Estrogens

Steroid hormones from ovaries that stimulate uterine lining growth and maintain female secondary sex characteristics.