Endocrinology

What is Endocrinology?

There are several mechanisms that regulate the essential bodily functions right from metabolism, water balance, growth, etc. The study of these mechanisms is called Endocrinology. 

What are Hormones and Endocrine Glands?

For a body to perform various functions within itself, it takes the help of electric signals passed throughout the neurons in our body as a communication medium. Hormones are such signals in the form of chemical substances which are transferred from the organ of release to target organs through the bloodstream  and upon this circulation, specific physiological responses are released by the target cells.

To achieve this release of hormones into the bloodstream, a coordinated mass of cells called the endocrine glands come into action. The hormones which are the secretory products of the endocrine glands are released into the extracellular space and diffuse across the bloodstream. Endocrine glands are also called ductless glands.

Functions of Hormones

The functions of hormones in a human can be broken down into 3 levels: Cellular level, Molecular level and Overall Body level:

• Cellular Level:

• Regulation of cell division, differentiation, apoptosis, motility, secretion, nutrient uptake

• Molecular Level:

• Regulation of gene transcription, protein synthesis and degradation 

• Enzyme activity. protein conformation and protein-protein interactions

• Overall Body Level:

• Regulation and integration of – ionic and fluid balance, energy balance (metabolism), coping with the environment, growth and development, reproduction 

The Major Endocrine Glands

1. Pituitary gland: 

This gland is attached to the hypothalamus located near the underside of the brain.

It is also called the master gland of the endocrine system. Some of the major hormones released by it and their respective functions are as follows-

• Growth hormone: this hormone primarily targets the growth and physical development of bones and muscles

• Thyroid-stimulating hormone: this hormone activates the thyroid gland to release thyroid hormone 

• Adrenocorticotropic hormone: this hormone stimulates the adrenal glands to produce cortisol and other hormones.

• Follicle-stimulating hormone: this hormone stimulates estrogen secretion and the growth of egg cells in women along with sperm cell production in men.

• Luteinizing hormone: this hormone stimulates the production of estrogen in women and testosterone in men.

• Endorphins: these hormones have pain-relieving properties 

• Vasopressin: This hormone helps the body to conserve water and prevent dehydration.

• Oxytocin: this hormone stimulates the release of breast milk and also contractions of the uterus during labor.

2. Thyroid gland:

This gland surrounds the windpipe from three sides. Some of the major hormones released by it and their respective functions are as follows-

• Thyroxine: this hormone stimulates production of adrenaline and dopamine

• Triiodothyronine : this hormone too stimulates production of adrenaline and dopamine

3. Parathyroid gland: 

these glands lie behind the thyroid glands and secrete the parathyroid hormone which plays a major role in regulating calcium and phosphorus levels in human body

4. Islets of Langerhans: 

These are located in the form of clusters in the pancreas. They consist of three major types of cells – alpha, beta and delta cells. Some of the major hormones released by it and their respective functions are as follows-

• The beta cells produce the hormone insulin, which is responsible for regulation of carbohydrate, fat, and protein metabolism

• The alpha cells produce the hormone glucagon, which releases glucose from the liver and fatty acids from fat tissue

• The delta cells produce the hormone somatostatin, which is a strong inhibitor of somatotropin, insulin, and glucagon

5. Gonads or Reproductive glands: 

the gonads secrete hormones related to sexual characteristics development in male and female.They are responsible for the production of steroid hormones, such as testosterone, estrogen, and progesterone.

• Testosterone: this hormone regulates the development and function of the primary sex organs and secondary male characteristics in males

• Estrogen and progesterone: these hormones are responsible for the development of secondary sex characteristics and the preparation of the body for childbirth

Endocrine Diseases 

Endocrine diseases or disorders can be broadly classified into 5 categories according to their cause – 

1. Hormone Overproduction: 

Sometimes due to genetic abnormalities, hormones are released in abnormally increased amounts causing subsequent problems in their synthesis and respective functions. These are often caused due to an increase in the number of hormone-producing cells. Examples of this category of diseases are: glucocorticoid-remediable hyperaldosteronism, Graves’ disease

2. Hormone Underproduction: 

This category of diseases can have plenty of causes like – surgical removal of thyroid glands, iron deposition in beta cells of islets in hemochromatosis etc. The hormone producing cells are often destroyed due to autoimmunity. Examples of this category of diseases are: type 1 diabetes, Hashimoto’s thyroiditis

3. Altered Tissue Response: 

This type of disease are caused due to mutations in signal reception and propagation by some cells. Examples of this category of diseases are:  Laron dwarfism, pseudohypoparathyroidism type 1A

4. Tumors of Endocrine Glands: 

Sometimes tumors in endocrine glands lead to overproduction of hormones, and cause disease through local compressive symptoms or metastatic spread.Examples of this category of diseases are: nonfunctioning pituitary tumors

5. Excessive Hormone Inactivation or Destruction: 

In the human body there exist a few enzymes whose function is to inactivate any particular hormone production in a physiologically regulated fashion. Sometimes this rate becomes higher than required causing diseases like – iodothyronine deiodinase type 3, consumptive hypothyroidism etc

Conclusion

This article was focused on endocrinology and described its functions and importance in detail. Hope the students now have a clear view on the topic of endocrinology. If students have any queries regarding the topic they can ask.