Definition, function of hormones, and their types

 Hormones are chemicals that are naturally secreted in the body , through glands that work to bring balance to the body.


There is a system in the body called (the endocrine system) , and these glands secrete hormones in the body . 


examples of these glands – the pancreas, the adrenal or suprarenal glands , the pituitary gland , and the thyroid gland .



 Definition of hormones

 Hormones are chemicals that have a strong and important effect ; in the body of an organism , both human and animal .


In the event of any imbalance in the production of these hormones than their normal rates . many problems occur to humans , so we will explain to you more details about hormones, their function , and their types .


 Function of hormones

  •  Each part of the human body has a specific function , which is led by the nervous system in cooperation with the endocrine system . 


  •  The endocrine glands send out hormones ; that tell every part of your body what task it has to do , when it has to do it , and how long it will take.


  • Hormones are the substances ; that give life to your body .


  • Hormones cross the bloodstream into tissues or organs ; to help them do their job . This affects many vital functions , such as physical growth , development , metabolism (how your body gets energy from the foods you eat), and reproduction , etc .


  • Hormones play a major role in determining , the levels of human appetite for food .


  • Hormones are involved in most bodily functions , including blood pressure , heart rate , and respiratory rate .


  • Some hormones act as neurotransmitters to influence mood , and the general state of mind of a person .


  • Certain hormones, such as serotonin and dopamine , act as neurotransmitters – chemicals . that transmit messages between nerve cells in the brain and muscle cells in skeletal muscle ,  to help coordinate skeletal muscle movement .


  •  Hormones interact with each other , and with many other body systems including the immune system .


 Types of hormones

  • Hormones are secreted by the endocrine glands of the body .  They are glands without a duct , so hormones are secreted directly into the bloodstream , not through ducts .


  • Some of the major endocrine glands in the body include : pituitary gland , thyroid gland , adrenal glands , pancreas , testes , and ovaries .


  • These organs secrete the hormone in microscopic amounts , and only require very small amounts , to bring about major changes in the body . 


  • Even a very slight increase in the secretion of the hormone can lead to disease conditions .


  • Hormones are classified according to the chemical composition from which they are derived , as they can be called derivatives of amino acids , they are synthesized from amino acids .


  • They can be called peptide hormones as they are made from short chains of amino acids . Or it can be called fat derivatives , if it is made from derivatives of fatty amino acids .


  • You may have heard before about certain hormones like adrenaline , insulin or testosterone , but there are other important hormones that I suspect you haven’t heard of.


  • Unless you know someone who has a problem with , their endocrine system . There are many hormones in the body , which are secreted by several organs , and the most important of these hormones are :


  1.  (1) – Thyroid hormones .
  2. (2) – pancreatic hormones .
  3. (3) – Hypothalamic hormones .
  4. (4) – pituitary gland hormones .
  5. (5) – reproductive hormones .
  6. (6) – adrenal gland hormones .
  7. (7) – pineal gland hormone .
  •  (1) – Thyroid hormones

 The thyroid gland releases the two hormones triiodothyronine , thyroxine , which helps control the body’s metabolism .


Moreover , these hormones regulate weight , determine energy levels , internal body temperature , skin and hair .


 The hormone thyronine is one of the most influential hormones on the body . as it plays important roles in controlling our metabolic rate , heart and muscle function , digestive processes , brain development , its function , and maintaining bone health .


  •  (2) – pancreatic hormones

 The pancreas produces a number of hormones that play an important role in maintaining the balance of sugar , and salt in our bodies . The hormones secreted by the pancreas include :


  • (a) Gastrin : This hormone aids digestion , by stimulating certain cells in the stomach to produce acid .


  • b) Glucagon :  works in an opposite way to insulin , it stimulates your cells to release glucose and this raises blood glucose levels .


  • (c) Insulin : You may think of insulin when the treatment of diabetes is mentioned , because it is used as a booster for naturally produced insulin , when its quantity is insufficient in the body .


Insulin is secreted by the pancreas , and the main role of insulin is to help the body absorb glucose as energy for the body .


  • (d) Somatostatin : When levels of other pancreatic hormones , such as insulin and glucagon , rise , somatostatin is released to maintain glucose or salt balance in the blood .


  • (3) – Hypothalamic hormones

 The hypothalamus is largely involved in the function of the pituitary gland , when it receives a signal from the nervous system , the hypothalamus (the link between the autonomic nervous system .


and the secretory system through the pituitary gland), secretes substances known as neurohormones ; that start or stop the secretion of gland hormones  pituitary ;  The hormones secreted by the hypothalamus include :


  • (a) Antidiuretic hormone (ADH): This hormone increases the absorption of water into the blood by the kidneys.


  • (b) Corticotropin-releasing hormone (CRH) : This hormone sends a message to the anterior pituitary gland , to stimulate the adrenal glands , to secrete a chemical called corticosteroids . which helps regulate the metabolism and immune response .


  •  (4) – pituitary gland hormones

 The pituitary gland produces many hormones, the most important of which are:


  • (a) Growth hormone :

 Stimulates the growth of bones and tissues, and a deficiency of this hormone leads to failure to thrive , and problems in maintaining the proper amounts of body fat and muscle and bone mass .

  • (b) Thyroid hormone (TSH) : stimulates the thyroid gland to produce its own hormones.


  • (c) Adrenocorticotropic hormone (ACTH): stimulates the adrenal gland to produce several steroid hormones.


  • (d) Luteinizing hormone (LH) and follicle-stimulating hormone (FSH) : These are the hormones that control sexual function and the production of sex steroids .


  • (5) – reproductive hormones

 Testosterone , is associated with males , but you might be surprised to learn ; that it is also present in females (albeit in smaller amounts) .


It is produced by the adrenal gland in both sexes , by the testes in men and the ovaries in women . 


Its function in both sexes is to contribute to the formation of new blood cells , help in strengthening bones and developing muscles , in addition to its main role in the formation of sexual desire .


  • (a) Testosterone :

 In males , it is the hormone necessary for the appearance of secondary male characteristics in adults , and this includes amplification of the voice , growth of facial and body hair , growth of the penis and testicles , and production of sperm .


  • (b) Estradiol :

 Estradiol is the most powerful female hormone of the group of estrogens . Estrogen is produced by the ovaries , and in much higher amounts in women than in men .


The main function of estradiol is to help our body determine the appropriate age for puberty , as well as its main role in the development and maintenance of the female reproductive system.


It is a major component of breast development , pubic hair growth and the widening of the hips .


In addition to its regulation of the female menstrual cycle , its contribution to bone formation , the process of blood clotting , and the health of your skin and nails . 


  • (c) Gonadotropin-releasing hormone (GnRH) :

stimulates the anterior pituitary gland to secrete follicle-stimulating hormone (FSH) , and luteinizing hormone (LH) . which work together to ensure the normal functioning of the ovaries and testicles .


  • (d) Oxytocin :

It is involved in a variety of processes such as orgasm , confidence , body temperature , sleep cycles , and secretion of breast milk .


  • (e) Prolactin-releasing hormone (PRH) :

It stimulates the anterior pituitary gland to stimulate the production of breast milk , through the production of prolactin .


  •  (6) – pineal gland hormone

 The pineal gland in your brain produces the hormone melatonin , which plays an essential role in your sleep and wake cycles and your body’s biological clock . 


When it gets dark , your brain raises your melatonin levels to prepare you for sleep , so exposure to light during sleep lowers your melatonin levels , and your sleep quality decreases , which is what constant exposure to screens does when you fall asleep .


Thus, we see that hormones are the basis for all the vital functions of our body , so make sure to maintain their health to be at your help for as long as possible in your life .


  • (7) – adrenal gland hormones

 The adrenal glands are two glands located above your kidneys.They consist of two distinct parts. They secrete a number of hormones as follows :


  • (a) Adrenal cortex hormones:

adrenal cortex produces two main groups of corticosteroid hormones :

glucocorticoids , and mineralocorticoids . The glucocorticoids secreted by the adrenal cortex include :

  •  (b) hydrocortisone :

 Known as cortisol , it regulates how the body converts fats , proteins , and carbohydrates into energy .


It also helps regulate blood pressure , and cardiovascular function .


  • (c) corticosterone :

This hormone works with hydrocortisone to regulate , the immune response and suppress inflammatory reactions .

  • (d) Primary mineralocorticoids :

 It releases the hormone aldosterone , that maintains the proper balance of salt and water , while helping to control blood pressure .