Hormones-Classification

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The term hormone is got from the Greek word ‘horman’ and it means ‘to excite’ or ‘to activate’. Hormones act as chemical messenger involved in transmission of information to the target organs.

Classification of hormones

Based on chemical nature, hormones are classified into three groups.

  • Protein or peptide hormones

            Examples are insulin, glucagon, oxytocin, anti-diuretic hormone

  • Steroid hormones

Examples are Glucocorticoids, mineralocorticoids, testosterone, estrogen, progesterone

  • Amino acid derivatives

Examples are adrenaline, nor adrenaline, thyroxine, tri-iodothyronine

Based on receptor binding, they are classified into

  • Group 1 Hormones

They are lipophilic hormones that bind intracellular receptors to form hormone-receptor complexes. Examples are estrogen, calcitrol, androgens, thyroxine.

  • Group 2 Hormones

These are hydrophilic hormones unable to diffuse through plasma membrane. These act as primary messengers and transfers signals to secondary messengers. Examples are adenylate cyclase and phosphatidyl inositol.

Based on the site of production,

  • Hormones of  pituitary

Examples are growth hormone, thyroid stimulating hormone, oxytocin, vasopressin

  • Hormones of thyroid gland

The hormones are thyroxine, tri-iodo thyronine, thyrocalcitonin

  • Hormones of parathyroid

Parathormone and calcitonin are secreted in parathyroid gland

  • Adrenal hormones

Corticosteroids and sex hormones are examples for this group

  • Pancreatic hormones

Insulin and glucagon are secreted by islet of langarhans of endocrine pancreas

  • Thymus gland hormone

Thymosin is secreted here which produces T lymphocytes

  • Pineal gland hormones

Melatonin and an unknown substance which inhibits puberty

  • Local hormones

Acetyl choline, serotonin, prostaglandins come under this group. They act as chemical mediators and act around the area of secretion. Hence they are known as local hormones.

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