What are Hormones?

Hormones are chemicals that are responsible for

controlling and regulating the activities of certain cells and
organs. These chemicals are secreted by special glands
known as the endocrine glands.
These endocrine glands are distributed throughout the
body. These messengers control many physiological
functions as well as psychological health. They are also
quite important in maintaining homeostasis in the body.
The effects of hormones depend on how they are
released:
Autocrine: The hormone act on the cell that secreted it.
Paracrine: The hormone act on a nearby cell without
having to enter the blood circulation.
Intracrine: The hormone is produced in the cell and acts
intracellular means inside the cell.
Endocrine: The hormone act on the target cells once it is
released from the respective glands into the bloodstream.
Types of Hormones
1. Peptide Hormones
Peptide hormones are composed of amino acids and are soluble in water.
Peptide hormones are unable to pass through the cell membrane as it
contains a phospholipid bilayer that stops any fat-insoluble molecules
from diffusing into the cell. Insulin is an important peptide hormone
produced by the pancreas.

2. Steroid Hormones
Unlike peptide hormones, steroid hormones are fat-soluble and are able to
pass through a cell membrane. Sex hormones such as testosterone,
estrogen, and progesterone are examples of steroid hormones.
Parts of the endocrine system and the Hormones Secreted
1. Hypothalamus: This gland is located in your brain and controls your
endocrine system. It controls the body temperature, regulates emotions,
hunger, thirst, sleep, moods and allow the production of hormones.
2. Pineal: Pineal is also known as the thalamus. It produces serotonin
derivatives of melatonin, which affects sleep patterns.
3. Parathyroid: This gland helps in controlling the amount of calcium present
in the body.
4. Thymus: It helps in the production of T-cells, functioning of the adaptive
immune system and maturity of the thymus.
5. Thyroid: Your thyroid is a butterfly-shaped gland in the front of your neck.
It produces hormones that affect the heart rate and how calories are burnt.
6. Adrenal: This gland produces the hormones that control the sex drive,
cortisol and stress hormone.
7. Pituitary: This little gland is only about the size of a pea, but it has
a big job. It makes hormones that control several other glands such as
the thyroid gland, adrenal glands, ovaries and testicles. The pituitary
gland is in charge of many different functions, including how your
body grows. It’s located at the base of your brain.
8. Pancreas: This gland is involved in the production of insulin
hormones, which plays a crucial role in maintaining blood sugar
levels.
9. Testes: In men, the testes secrete the male sex hormone,
testosterone. It also produces sperm.
10. Ovaries: In the female reproductive system, the ovaries release
estrogen, progesterone, testosterone and other female sex hormones.
All these glands work together to produce and manage the hormones
of the body.
Functions of Hormones:
Following are some important functions of hormones:
1. Food metabolism.
2. Growth and development.
3. Controlling thirst and hunger.
4. Maintaining body temperature.
5. Regulating mood and cognitive functions.
6. Initiating and maintaining sexual development and
reproduction.
List of important hormones and their functions
Hormones are the body's chemical messengers. They help tissues or organs
to do their work via travelling through the bloodstream. There are several
types of hormones that act on different aspects of bodily functions. Let us
have a look at the important hormones and their functions.

1. Hormones of Thyroid
Thyroid gland basically releases two hormones Triiodothyronine
(T3) and Thyroxine (T4), which helps in controlling the
metabolism of our body. Further, these hormones regulate
weight, determines energy levels, internal body temperature,
skin, hair etc.
 2. Insulin
This hormone is released by the pancreas, a leaf-like gland located in the
abdominal cavity behind the stomach. It allows the body to use glucose or
sugar from carbohydrates in the food for energy or to store glucose for future
use. It helps in keep blood sugar levels from getting too high i.e.
hyperglycemia or too low i.e. hypoglycemia.
3. Estrogen
It is a female sex hormone released by the ovaries. It is responsible for the
reproduction, menstruation and menopause. Excess of estrogen in the female
body increases the risk of breast cancer, uterine cancer, depression, moodiness
etc. If the estrogen level is less in female body then it leads to acne, skin
lesions, thinning skin, hair loss etc.
4. Progesterone
Progesterone hormone is produced in the ovaries, the placenta when a woman
gets pregnant and the adrenal glands. It stimulates and regulates various
functions. It plays an important role in maintaining pregnancy. It helps body to
prepare for conception, pregnancy and regulates the monthly cycle. When
pregnancy doesn’t occur, progesterone levels drop and menstrual cycle occurs. It
also plays a role in sexual desire.
5. Testosterone
It is a male sex hormone. It is an anabolic steroid by nature which helps in
building body muscles. In males, it plays an important role in the development
of male reproductive tissues; testes and prostate. It also promotes secondary
sexual characteristics like increasing the mass of muscles and bones, growth of
body hair etc. If testosterone is secreted insufficient in men then it may lead to
abnormalities including frailty and bone loss.
 6. Serotonin
It is a mood-boosting effect hormone or also known as nature’s feel-
good chemical. It is associated with learning and memory, regulating
sleep, digestion, regulates mood, some muscular functions etc. Due
to the imbalance of serotonin in the body, brain does not produce
enough of the hormone to regulate mood or stress level. Low level of
serotonin causes depression, migraine, weight gain, insomnia,
craving of carbohydrate etc. Excess level of serotonin in the body
causes agitation, stage of confusion, sedation etc.
7. Prolactin
This hormone is released by the pituitary gland after childbirth for lactation,
which enables female to breastfeed. Levels of prolactin hormone rise during
pregnancy i.e. it also plays an important role in fertility by inhibiting follicle-
stimulating hormone (FSH) and gonadotropin-releasing hormone (GnRH)
 8. Cortisol
This hormone is produced by the adrenal gland. It helps you stay healthy and energetic. Its
main role is to control physical and psychological stress. In danger condition, it increases
heart rate, blood pressure, respiration etc. At stressful times body secretes cortisol to cope
up with the situation. High level of cortisol consistently causes ulcer, high blood pressure,
anxiety, high levels of cholesterol etc. Similarly, a low level of cortisol in the body causes
alcoholism, a condition responsible for chronic fatigue syndrome etc.
9. Adrenaline
Adrenaline hormone is secreted in the medulla in the adrenal gland as well as some of the
central nervous system’s neurons. It is also known as an emergency hormone because it
initiates the quick reaction which makes the individual to think and respond quickly to the
stress. It increases the metabolic rate, dilation of blood vessels going to the heart and the brain.
During a stressful situation, adrenaline quickly releases into the blood, send impulses to the
organs to create a specific response.
10. Growth Hormone
It is also known as the somatotropin hormone. It is basically a protein
hormone having 190 amino acids which are synthesized and secreted by the
cells called somatotrophs in the anterior pituitary. It stimulates growth, cell
reproduction cell regeneration and in boosting metabolism. It is important in
human development.
Functions of Hormones:
Following are some important functions of hormones:
1. Food metabolism.
2. Growth and development.
3. Controlling thirst and hunger.
4. Maintaining body temperature.
5. Regulating mood and cognitive functions.
6. Initiating and maintaining sexual development and
reproduction.