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

22. CHEMICAL CO-ORDINATION AND INTEGRATION

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.

Hormone receptors are 2 types:

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.

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👇 Select Your Topic Here 👇

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