Major endocrine glands, their hormones and functions


  • The glands which do not have any duct are called ductless glands or endocrine glands.
  • Literally, the term ‘endocrine’ means internally secreting.
  • Their secretions are called internal secretions or hormones.
  • These are released directly into the blood, which carries them to different parts of the body, and where they coordinate their metabolic activities.
  • They are usually located far away from the site of their action.
  • The study of those glands and the hormones they produce is called endocrinology.
  • Some glands of the body, such as pancreas and gonads, are dual in nature, having both exocrine and endocrine functions.
  • Such glands are called heterocrine glands or mixed glands.
  • They have following main functions:
  1. Helps in maintaining homeostasis by regulating activities such as concentration of chemicals in body fluids and the metabolism of proteins, carbohydrates and lipids.
  2. Their secretions act in concert with the nervous system to help the body react to stress properly.
  3. They are major regulator of growth and development, including sexual development and reproduction.
  • They are of various types. They are as follows.

1) Posterior pituitary (neurohypophysis)

Hormones Function of hormones Means of control
Antidiuretic hormones (ADH, Vasopressin) Increases water absorption from kidney tubules.

Raises blood pressure.

Synthesized in hypothalamus, released from neurohypophysis.


Oxytoxin Stimulates contraction of pregnant uterus.

Milk ejection from breasts after childbirth.

Synthesized in hypothalamus released from neurohypophysis.

2) Anterior pituitary (Adenohypophysis)

Growth hormone (GH, somatotropic hormone, STH) Stimulates growth of bone, muscles.


Promotes protein synthesis, fat mobilization.


Slows carbohydrate metabolism.


Hypothalamic growth hormone releasing hormone (GHRH), growth hormone inhibiting hormone (GHIH).
Prolactin Promotes breast development during pregnancy.

Milk production after child birth.

Hypothalamic prolactin inhibiting hormone (PIH), prolactin releasing hormone (PRH).
Thyroid stimulating hormone (TSH) Stimulates production and secretion of thyroid hormones. Hypothalamic thyrotropin releasing hormone (TRH).
Adrenocorticotropic hormone (ACTH) Stimulates production and secretion of adrenal cortex steroids. Hypothalamic corticotropic releasing hormone (CRH).
Luteinizing hormone (LH) In female, stimulates development of corpus luteum, release of oocyte, production of progesterone and oestrogen.


In male, stimulates secretion of testosterone, development of interstitial tissues of testis.

Hypothalamic gonadotropin releasing hormone (GnRH).
Follicle stimulating hormone (FSH) In female, stimulates growth of ovarian follicle, ovulation.


In male, stimulates sperm production.

Hypothalamic gonadotropin releasing hormone (GnRH).
Melanocyte stimulating hormone (MSH) Apparently involved with skin color (melanocytes) in combination with ACTH, role uncertain. Uncertain.

3) Thyroid gland

Follicular cells
Thyroid hormones, thyroxin (T4), triiodothyronine (T3) Increase metabolic rate, sensitivity of cardiovascular system to sympathetic nervous activity.


Affect maturation, homeostasis of skeletal muscles.

Thyroid stimulating hormone (TSH) from adenohypophysis.


TSH regulated by thyrotropin releasing hormone (TRH) from brain.

Parafollicular cells
Calcitonin Lowers blood calcium and phosphate levels.

Acts on bone, kidney and other cells.

Blood calcium concentration.

4) Parathyroid glands

Parathormone (PTH, parathyroid hormone) Increases blood calcium and decreases blood phosphate level.


Acts on bone, intestine, kidney and other cells.


Blood calcium concentration.

5) Adrenal medulla

Epinephrine (adrenaline) Increase heart rate, blood pressure.


Regulates diameter of arterioles.


Stimulates contraction of smooth muscles.


Increases blood glucose concentration.

Sympathetic nerous system.
Norepinephrine (noradrenaline) Constricts arterioles.


Increases metabolic rate.

Sympathetic nervous system

6) Adrenal cortex

Glucocorticoids, mainly cortisol, corticosterone, 11- deoxycorticosterone. Affect metabolism of all nutrients.


Regulates blood glucose concentration.


Anti-inflammatories, affect growth.


Decrease effects of stress, ACTH secretion.

Corticotropin releasing hormone (CRH) from hypothalamus


ACTH from adenohypophysis.

Mineralocorticoids, mainly aldosterone Control sodium retention and potassium loss in kidney tubules. Angiotensin II


Blood potassium concentration.

Gonadocorticoids (adrenal sex hormones, androgens) Slight effect on ovaries and testes. ACTH

7) Pancreas

Beta-cells in pancreatic islets
Insulin Lowers blood glucose by facilitating glucose transport across plasma membranes.


Increasing glycogen storage.


Affects muscles, liver and adipose tissues.

Blood glucose concentration.
Alpha cells in pancreatic islets
Glucagon Increases blood glucose concentration. Blood glucose concentration.


Ovaries (follicle)
Estrogens Affects development of sex organs and female characteristics.


Initiates development of ovarian follicle.

Follicle stimulating hormone (FSH).
Ovaries (corpus luteum)
Progesterone , estrogens Influence menstrual cycle.


Stimulates growth of uterine wall, maintains pregnancy.

Luteinizing hormone (LH).
Estrogens, progesterone, human chorionic gonadotropin (HCG) Maintains pregnancy. Uncertain.
Androgens, mainly testosterone Affects development of sex organs and male characteristics.


Aids sperm production.

Luteinizing hormone.


9) Thymus

Thymosin alpha, thymosin B1 to B5, thymopoietin I and II, thymic humoral factor (THF), factor thymic serum (FTS), thymostimulin Help develop T-cell in thymus.


Maintain T-cells in other lymphoid tissues.


Involved in development of some B- into antibody producing plasma cells.


10)Digestive system

Secretin Stimulates release of pancreatic juice to neutralize stomach acid. Acid in small intestine.
Gastrin Produces digestive enzymes and hydrochloric acid in stomach. Food entering stomach.
Cholecystokinin (CCK) Stimulates release of pancreatic enzymes.


Gall bladder contraction.

Food in duodenum.

11) Heart

Atriopeptin (atrial natriuretic factor, ANF). Helps maintain balance of fluids, electrolytes.


Decreases blood pressure and volume.

Salt concentration, blood pressure and blood volume.

12) Kidney

Renin Acts upon plasma protein angiotensinogen. Decrease blood pressure

13) Pineal body

Melatonin Regulates developments of gonads.


Slows menstrual cycle in females.







Major endocrine glands, their hormones and functions