Hormones

Hormones Definition

“Hormones are chemicals released by the body to control and regulate the activity of certain cells and organs. Special glands known as endocrine glands secrete these hormones.”

What are Hormones?

As stated above, hormones are chemicals that essentially function as messengers of the body. 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.

Cell Signaling

The effects of hormones depend on how they are released. Hence, signalling effects can be classified into the following:

  • Endocrine: The hormone act on the target cells once it is released from the respective glands into the bloodstream.
  • Paracrine: The hormone act on a nearby cell without having to enter the blood circulation.
  • Autocrine: The hormone act on the cell that secreted it.
  • Intracrine: The hormone is produced in the cell and acts intracellularly.

Types of Hormones

To regulate various functions, different types of hormones are produced in the body. They are classified as follows:

  • Peptide Hormones
  • Steroid Hormones

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.

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.

Endocrine Glands and the Hormones Secreted

As stated before, hormones are released by the endocrine glands. These are different from other glands of the human body as they are ductless.

  • Hypothalamus: It regulates the body temperature, controls thirst, sleep, hunger, emotions, moods and allow the release of hormones.
  • Pineal: Pineal is also known as the thalamus, it develops serotonin derivatives of melatonin, which can affect sleep.
  • Parathyroid: This gland helps in controlling the amount of calcium present in the body.
  • Thymus: It helps in the functioning of the adaptive immune system, produces T-cells and maturity of the thymus.
  • Thyroid: It produces hormones that affect the heart rate and how calories are burnt.
  • Adrenal: This gland produces the hormones that control the sex drive, cortisol and stress hormone.
  • Pituitary: It is also termed as the “master control gland,”. This is because the pituitary gland helps in controlling other glands. Moreover, it develops the hormones that trigger growth and development.
  • Pancreas: This gland produces insulin crucial to maintain blood sugar levels.
  • Testes: In men, the testes secrete the male sex hormone, testosterone. It also produces sperm.
  • Ovaries: In women, the ovaries secrete estrogen, progesterone, testosterone, and other female sex hormones.

All these glands work together to produce and manage the hormones of the body.

List of Important Hormones

  1. Estrogen-This is the main sex hormone present in women which bring about puberty, prepares the uterus and body for pregnancy and even regulates the menstrual cycle. Estrogen level changes during menopause because of which women experience many uncomfortable symptoms.
  2. Progesterone – It is a female sex hormone also responsible for menstrual cycle, pregnancy and embryogenesis.
  3. Cortisol – It has been named as the “stress hormone” as it helps the body in responding to stress. This is done by increasing the heart rate, elevating blood sugar levels etc.
  4. Melatonin – It primarily controls the circadian rhythm or sleep cycles.
  5. Testosterone – This is the main sex hormone present in men which cause puberty, muscle mass growth, and strength, increases bone density and handles facial hair growth.

Also Read: Animal Hormones

Functions of Hormones

Following are some of the important functions of hormones:

  • Growth and development.
  • Food metabolism.
  • Initiating and maintaining sexual development and reproduction.
  • Maintaining body temperature.
  • Controlling thirst and hunger.
  • Regulating mood and cognitive functions.

Also Read: Plant Growth Regulators

Hormonal Diseases

Several hormonal diseases arise when the endocrine glands malfunctions. Common hormonal issues are associated with hypothalamus, adrenal and pituitary glands. An increase or decrease in the secretion of these hormones can severely affect growth, metabolism and development.

Diseases such as hyperthyroidism, osteoporosis, and diabetes are caused due to hormonal imbalance. The factors responsible for hormonal diseases can be genetic, environmental, or related to diet.

Frequently Asked Questions

1. What is a hormone? What does it do?

Hormones are the chemicals that are responsible for controlling and regulating the activities of certain cells and organs. These hormones are secreted by ductless glands known as endocrine glands

2. List the types of Hormones.

Hormones are classified into two types, namely: Peptide hormones and steroid hormones.

3. Name 3 diseases caused by hormonal imbalance.

  • hyperthyroidism
  • osteoporosis
  • diabetes

3. What are hormones made of?

Hormones are made of either proteins or steroids.

4. Name the hormone produced by the adrenal glands.

The hormone released by the adrenal glands is called Epinephrine. It is also called adrenaline.

5. Name the hormone produced by the pineal gland.

The hormone produced by the pineal gland is Melatonin. It regulates the body’s sleep cycle.

6. Which are the hormones produced by the thyroid gland?.

The thyroid gland is responsible for producing thyroxine, triiodothyronine, and calcitonin.

7. Name the glands responsible for producing Testosterone.

In males, testosterone is produced by the testes while ovaries produce the same hormone in females.

8. Name the glands responsible for producing Progesterone.

Progesterone is produced by the ovaries.

9. Name the hormone responsible for Gigantism.

The hormone responsible for gigantism is growth hormones, which are released by the pituitary gland.

10. What causes Acromegaly?

Acromegaly is the result of excess production of the growth hormone by the pituitary gland, commonly as a result of a benign tumour.

Also Read:

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