Endocrine Glands and Hormones

The human endocrine system constitutes the various endocrine glands and hormones secreted by them. This story provides information regarding the same.

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.

The following list below are all the endocrine glands and the respective hormones they secrete, which regulate the various important physiological processes:

Pineal Gland

• Melatonin

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

Thyroid Gland

• Triiodothyronine
• Thyroxine
• Calcitonin

Thymus Gland

• Thymosins

• Glucocorticoids
• Mineralocorticoids
• Androgens
• Adrenaline
• Noradrenaline
• Dopamine
• Enkephalin

• Insulin
• Somatostatin
• Glucagon
• Pancreatic Polypeptide

Liver

• Somatomedin
• Angiotensin
• Thrombopoietin

Testes (males)

• Androgens (testosterone)
• Estradiol
• Inhibin

• 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.

Below is a sorted list which is drafted gland-wise, depicting individual effects of each hormone upon the human body, and what parts of the human physiology are governed by it:

PINEAL GLAND
➔ Melatonin ➔ Melatonin Receptors

Grips 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.

PITUITARY GLAND 
➔ 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.

THYROID GLAND
➔ 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

THYMUS GLAND
➔ Thymosins ➔ Immune system

Act as biological response modifiers with respect to diseases and infections.

ADRENAL GLANDS
➔ 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. 

PANCREAS
➔ Insulin ➔ Fat and carbohydrate metabolism

Encourages the body to use up glucose as a source of energy.

➔ 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.

LIVER
➔ 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

TESTES
➔ 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.

OVARIES
➔ 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 story is for informative purposes only, and should not be used as a replacement for expert medical advice.