Classification of Hormones

Introduction

• Hormones are the chemical substance/chemical messengers synthesized by endogenous glands and secreted directly into the blood circulation, but only target cells are equipped to respond.

Classification of Hormones

• Chemically Classification of Hormones can be divided into seven major classes.

1. Amino acid derivatives – Dopamine, Catecholamine, Thyroid hormone.

2. Neuropeptides – Gonadotropin-releasing hormone, Somatostatin.

3. Simple proteins – Corticotropin (ACTH).

4. Large proteins – Insulin, Luteinising hormone (LH), Parathyroid hormone (PTH).

5. Glycoprotein – Thyroid-stimulating hormone (TSH).

6. Steroids – Cortisol, Estrogen, Progesterone, Glucocorticoids.

7. Vitamins – Vitamine D.

• The hormones also can be divided into two general classes based on their solubility in water.
• The water-soluble – amine (epinephrine) and peptide/protein hormones.
• The lipid-soluble hormones – thyroid hormone, steroid hormones, and Vitamin D₃.

Functions of Hormones:

• Growth and differentiation.
• Maintenance of Homeostasis.
• Regulation and integration of reproductive function.

Hormone Receptors

• Hormone receptors are divided into 3 classes.

1. Membrane receptor:

• Mainly neuropeptide hormone and catecholamine bind with membrane receptors.
• There are several types of membrane receptors:

• G-protein coupled receptor – NE, E, DA, FSH, LH, PTH, ACTH (through adenylatecAMP system), Oxytocin, vasopressin (through the phospholipase-C-inositol system.
• Tyrosine-kinase receptor – Insulin, growth hormone, growth factor.
• Cytokine receptor – Prolactin and growth factor.
• Serine kinase receptor – transforming growth factor-β, bone morphogenic protein.

2. Cytosolic receptors:

For steroidal hormones (glucocorticoids, mineralocorticoids, estrogens, progestins, and androgens.

3.Nuclear receptors:

For Thyroid hormones T₃ and T₄.

Source of Hormones

Natural Human: (GH; LH and FSH; hCG); Animal (insulin, T₃ and T₄.

Biosynthetic: Insulin (porcine and bovine)

Synthetic Most hormones and their antagonists by DNA recombinant technology.

Make sure you also check our other amazing Article on : The Pituitary Gland