Chemical Coordination and Integration - Notes | Class 11 | Part 5: Mechanism of Hormone Action

Mechanism of Hormone Action

• Hormones produce their effects by binding to the specific proteins (hormone receptors) located in target tissues.
• A hormone binds to its specific receptor to form hormone-receptor complex. It leads to biochemical changes in target tissue and thereby regulates metabolism and physiological functions.
• Based on the chemical nature, hormones are various types:
• Peptide, polypeptide, protein hormones: Insulin, glucagon, pituitary hormones, hypothalamic hormones etc.
• Steroids: Cortisol, testosterone, estradiol & progesterone.
• Iodothyronines (thyroid hormones).
• Amino-acid derivatives: Adrenaline, hormone.

• Hormone receptors are 2 types: Membrane-bound receptors and Intracellular receptors.

1. Membrane-bound receptors

• Some hormones (e.g. protein hormone, FSH) interact with membrane-bound receptors (do not enter the target cell).
• It generates second messengers (e.g. cyclic AMP, IP₃, Ca²⁺). It in turn regulates cellular metabolism and causes physiological effects.

2. Intracellular receptors (mostly nuclear receptors)

• Some hormones (e.g. steroid hormones, iodothyronines) interact with intracellular receptors.
• They mostly regulate gene expression or chromosome function by the interaction of hormone-receptor complex with the genome.
• Cumulative biochemical actions result in physiological and developmental effects.

Select a Topic 👇

1. Hypothalamus, Pituitary and Pineal Glands 2. Thyroid and Parathyroid 3. Thymus, Adrenals and Pancreas 4. Testis, Ovary, Hormones of Heart, Kidney & Gastrointestinal Tract 5. Mechanism of Hormone Action

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