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Endocrine Glands and Hormones

Endocrine Glands and Hormones

The human endocrine system constitutes the various endocrine glands and hormones secreted by them. This article provides information regarding the same.
Ishani Chatterjee Shukla
The human body is composed of various physiological systems such as the central nervous system, the circulatory system, the musculoskeletal system, and the endocrine system. The endocrine glands are a set of ductless glands in our body and these glands secrete chemical enzymes known as hormones, and release them into the bloodstream. These hormones act as chemical signals which regulate various functions of the body such as growth of muscles, bones and hair, maturity of reproductive organs, etc. Hormones can be understood as chemical equivalents of electrical brain signals.

Endocrine Glands and Their Secretions

The following table lists all the endocrine glands and the respective hormones they secrete, which regulate the various important physiological processes:

Pineal Gland
  • Melatonin

Pituitary Gland
  • Somatotropin
  • Thyrotropin
  • Corticotropin
  • FSH
  • Lutropin
  • Prolactin
  • Oxytocin
  • Vasopressin
  • MSH (intermedins)

Thyroid Gland
  • Triiodothyronine
  • Thyroxine
  • Calcitonin

Thymus Gland
  • Thymosins

Adrenal Glands (cortex and medulla)
  • Glucocorticoids
  • Mineralocorticoids
  • Androgens
  • Adrenaline
  • Noradrenaline
  • Dopamine
  • Enkephalin

  • Insulin
  • Somatostatin
  • Glucagon
  • Pancreatic Polypeptide

  • Somatomedin
  • Angiotensin
  • Thrombopoietin

Testes (males)
  • Androgens (testosterone)
  • Estradiol
  • Inhibin

Ovaries (female)
  • Estrogen
  • Progesterone
  • Inhibin

Although the hypothalamus is not an endocrine gland, its functions include secretion of various hormones like TRH, Dopamine, GHRH, Somatostatin, GnRH, CRH, Oxytocin, and Vasopressin.

All the aforementioned hormones have different and important functions in our physiological system. They are responsible for sending signals to various different organs. They also regulate the important aspects of the complete human anatomy and physiology, such as metabolism, growth, moods, emotions, tissue function, etc.

Hormones and Their Functions

The following are separate tables, drafted gland-wise, depicting individual effects of each hormone upon the human body, and what parts of the human physiology are regulated by it:

➔ Melatonin ➔ Melatonin Receptors
Controls the sleep-wake cycle by inducing drowsiness in darkness (night times) and lowering the body temperature to suit the circadian rhythm. It also acts as an antioxidant by being able to transcend cell membranes and the barrier between blood and brain.

➔ Somatotropin ➔ Tissue Growth
Tissue growth stimulation as well as encouragement of cell production. Also stimulates the release of IGF-1 from the liver.

➔ Thyrotropin Thyroid Gland
Stimulates the production and release of thyroid hormones like thyroxine and triiodothyronin by the thyroid gland. Also regulates and encourages the absorption of iodine by the thyroid gland.

➔ Corticotropin ➔ Adrenal Glands
Stimulates the adrenal glands and regulates the production, release, and synthesis of glucocorticoid, mineralocorticoid, and androgens by the adrenals.

➔ FSH (Follicle Stimulating Hormone) ➔ Reproductive organs and processes
Development, growth, and maturity of the reproductive organs and processes.

➔ Lutropin ➔ Ovaries and Testes
Triggers the ovulation and corpus luteum development in females, and stimulates the production of Leydig cells in males.

➔ Prolactin ➔ Mammary Glands (females)
Kickstarts the lactation process in nursing females by stimulating lactation.

➔ Oxytocin ➔ Mammary glands and uterus (females)
Stimulates the milk releasing reflex while breastfeeding and induces contractions of the uterus during labor.

➔ MSH (Melanocyte Stimulating Hormone) ➔ Skin color pigments
Increased secretion causes darkening of the skin.

➔ Vasopressin ➔ Kidney, cardiovascular system, central nervous system
Stimulates water retention leading to the concentration of urine, narrows down the blood vessels and causes blood pressure to increase, regulates memory formation, etc.

➔ Triiodothyronine ➔ Growth, development, body temperature, heart rate, metabolism
Stimulates RNA Polymerase production, affects glucose metabolism and accelerates glycogen synthesis, enhances LDL receptors and accelerates lipolysis, enhances cardiac output, heightens brain serotonin levels, etc.

➔ Thyroxine➔ Metabolic system
Accelerates the basal metabolic rate, enhances the rate of oxygen consumption by the body, promotes the synthesis of protein by stimulating RNA Polymerase

➔ Calcitonin ➔ Blood calcium regulation
Lowers blood calcium to balance the effects of parathryn

➔ Thymosins ➔ Immune system
Act as biological response modifiers with respect to diseases and infections.

➔ Glucocorticoids ➔ Glucose regulation and metabolism
Regulates the expression of anti-inflammatory and pro-inflammatory proteins, stimulates glucose metabolism, active role in fetal development (especially lungs), stimulates emotional arousal and cognitive faculties.

➔ Mineralocorticoids ➔ Kidneys
Stimulates the kidneys to actively reabsorb sodium and passively reabsorb water.

➔ Androgens (testosterone, DHEA, etc.) ➔ Male reproductive system
Development and maintenance of physical and sexual traits of males such as facial hair, voice, musculature, etc.

➔ Adrenaline ➔ Almost all body tissues
A permutation and combination of multiple effects throughout the body tissues that lead to enhanced blood glucose and fatty acid levels, leading to production of energy within all cells of the body. This is known as the fight-or-flight response, wherein the muscles are tensed and the mind is highly alert and prepared to tackle stressful situations.

➔ Noradrenaline ➔ Attention and response centers of the brain
Elicits fight-or-flight response by inducing stress.

➔ Dopamine ➔ Brain and neurotransmission
Induces a state of nervous excitement by accelerating heart rate and increasing blood pressure.

➔ Enkephalin ➔ Pain reception and feeling
Regulates the brain's reception, and translation and processing of physically unpleasant stimuli.

➔ Insulin ➔ Fat and carbohydrate metabolism
Encourages the body to use up glucose as a source of energy.

➔ Somatostatin ➔ Growth hormone inhibition
Keeps the insulin and glucagon limits in check while inhibiting exocrine secretion.

➔ Glucagon ➔ Blood glucose levels
Balance insulin's action by decreasing the blood glucose levels.

➔ Pancreatic Polypeptide ➔ Pancreatic Secretions
Regulation of endocrine and exocrine activities of the pancreas.

➔ Somatomedin ➔ Cellular growth and development
Regulates growth and developments of cells and has certain effects that are similar to insulin.

➔ Angiotensin ➔ Circulatory System
Constricts the blood vessels to heighten the blood pressure

➔ Thrombopoietin ➔ Blood and bone marrow
Regulates the platelet production by bone marrow

➔ Androgens (testosterone) ➔ Male Reproductive System
Development and maintenance of physical and sexual traits of males such as facial hair, voice, musculature, etc.

➔ Estradiol ➔ Reproductive and skeletal system
Prevents apoptosis of sperm cells.

➔ Inhibin ➔ Regulation of FSH
Inhibits the production and synthesis of FSH in males.

➔ Estrogen ➔ Female Reproductive System and Skeletal System
Stimulates the development of secondary female sexual characteristics, inhibits the muscle mass development in females, stimulates the uterine development and endometrial growth, inhibits the reabsorption of bones, etc.

➔ Progesterone ➔ Female reproductive system and process
Regulates the menstruation, gestation, and embryogenesis.

➔ Inhibins ➔ FSH
Inhibits FSH

Thus, the aforementioned chemical mediators effectively regulate the vital physiological functions like the heart rate, insulin production, etc., besides regulating our moods and emotions.

Disclaimer: This Bodytomy article is for informative purposes only, and should not be used as a replacement for expert medical advice.