Mechanism of Hormone Action
Understanding how hormones communicate with your body’s cells
🌟 What Are Hormones?
Hormones are special chemical messengers that help coordinate and regulate your body’s functions. They travel through your bloodstream to target tissues where they trigger specific actions.
These amazing chemicals help control things like your metabolism, growth, development, and even how your organs function!
🧬 Where Do Hormones Come From?
While we have special hormone-producing glands (like the pituitary and thyroid), hormones also come from some unexpected places!
❤️ Heart Hormone
Your heart’s atrial wall makes ANF (Atrial Natriuretic Factor) which:
- Lowers blood pressure
- Causes blood vessels to expand
- Works when blood pressure gets too high
🩸 Kidney Hormone
Kidneys produce Erythropoietin which:
- Stimulates red blood cell formation
- Helps with oxygen transport
🍽️ Digestive Tract Hormones
Your GI tract makes four important hormones:
- Gastrin: Triggers stomach acid
- Secretin: Stimulates pancreas
- CCK: Activates pancreas & gallbladder
- GIP: Slows stomach activity
⚙️ How Hormones Work: The Mechanism
Hormones work like keys that fit into special locks on your cells called receptors. When a hormone finds its matching receptor, amazing things happen!
Key Concept: Hormone-Receptor Complex
When a hormone binds to its specific receptor, they form a hormone-receptor complex. This complex then triggers changes in the target cell.
🔍 Two Types of Receptors
🔒 Membrane-Bound Receptors
- Located on the cell surface
- Used by hormones that can’t enter cells
- Create second messengers inside the cell
- Examples: Protein hormones like insulin
🧬 Intracellular Receptors
- Located inside the cell (mostly in nucleus)
- Used by hormones that can enter cells
- Directly affect genes and DNA
- Examples: Steroid hormones like estrogen
📡 How Different Hormones Work
🔵 Protein Hormones (Like FSH)
1. Hormone binds to surface receptor
2. Creates second messengers like:
3. These messengers trigger changes in the cell
4. Results in growth or other responses
🔴 Steroid Hormones (Like Estrogen)
1. Hormone enters the cell
2. Binds to receptor inside (often in nucleus)
3. Hormone-receptor complex interacts with DNA
4. Affects gene expression and protein production
5. Leads to growth and development changes
🧪 Hormone Types Based on Chemistry
Hormones come in different chemical forms that determine how they work:
Peptide/Protein Hormones
Insulin, glucagon, pituitary hormones
Steroid Hormones
Cortisol, testosterone, estradiol, progesterone
Iodothyronines
Thyroid hormones
Amino-Acid Derivatives
Epinephrine (adrenaline)
🚀 Important Concepts for NEET
Here are key topics that frequently appear in exams:
Receptor Types
Membrane-bound vs. intracellular receptors – know which hormones use each type!
Second Messengers
Understand messengers like Cyclic AMP, IP\(_3\), and Ca\(^{++}\) – how they work and which hormones use them
Hormone Classification
Be able to classify hormones by chemical nature (peptide, steroid, etc.) and their mechanisms
Hormone-Receptor Complex
Know how this complex forms and its role in cellular responses
Non-Endocrine Hormones
Remember hormones from heart (ANF), kidney (erythropoietin), and GI tract
📝 Summary
- Hormones are chemical messengers that regulate body functions
- They bind to specific receptors on or in target cells
- Formation of hormone-receptor complex triggers cellular changes
- Protein hormones use surface receptors and second messengers
- Steroid hormones enter cells and affect gene expression
- Hormones come from endocrine glands and other organs too!
Remember: Your body’s hormone system is an amazing communication network that keeps everything in balance! 🌈
