◾ Exocrine glands are glands that release their secretions onto a body surface (like skin) or into a body cavity through ducts.
◾These secretions include enzymes, sweat, saliva, mucus, and other substances.
🧩 Memory Tip:
Exo = Exit ➝ Secretion exits through ducts.
Functions of Exocrine Glands
◾Digestion: Enzymes secreted help break down food (e.g., salivary, pancreas).
◾Lubrication & Protection: Mucus moistens surfaces and protects linings.
◾Temperature Regulation: Sweat glands help cool the body.
◾Waste Removal: Sweat glands also excrete waste products like urea.
◾Communication: Some glands release pheromones.
Types / Classification of Exocrine Glands
🔹A. Based on the Mode of Secretion
| Type | Description | Example |
|---|---|---|
| Merocrine | Secreted via exocytosis, no cell damage | Salivary glands, sweat glands |
| Apocrine | A portion of the cell pinches off | Mammary glands |
| Holocrine | Whole cell ruptures to release secretion | Sebaceous (oil) glands |
🧠 Mnemonic:
HAM ➝ Holocrine, Apocrine, Merocrine (in order of increasing damage to cells)
🔹B. Based on Structure
◾Unicellular glands – Single cell secreting directly (e.g., goblet cells)
◾Multicellular glands – Many cells, often with ducts (e.g., salivary glands)
🔹C. Based on Secretion Type
| Secretion Type | Gland Example |
|---|---|
| Serous (watery) | Parotid gland |
| Mucous (thick, slippery) | Sublingual gland |
| Mixed | Submandibular gland |
Examples of Exocrine Glands
| Gland Type | Location | Secretion |
|---|---|---|
| Salivary glands | Mouth | Saliva (enzymes for digestion) |
| Sweat glands | Skin | Sweat (cooling, waste removal) |
| Sebaceous glands | Skin | Oil (lubrication) |
| Lacrimal glands | Eyes | Tears (moisture, cleaning) |
| Mammary glands | Breasts | Milk |
| Pancreas (Exocrine part) | Abdomen | Digestive enzymes |
| Goblet cells | Respiratory/digestive tract | Mucus |
Difference: Exocrine vs Endocrine Glands
| Feature | Exocrine Glands | Endocrine Glands |
|---|---|---|
| Ducts | Present | Absent |
| Secretion | Onto the surface or cavity | Into blood |
| Examples | Salivary, sweat, and pancreas (exocrine part) | Pituitary, thyroid, and adrenal |
| Function | Local action (digestion, cooling) | Hormonal regulation (growth, metabolism) |
🧠 Analogy:
- Exocrine = Postal Service ➝ Delivers to specific addresses (via ducts)
- Endocrine = Wi-Fi ➝ Broadcasts signals (hormones) everywhere via blood
Exam Facts / One-liners / MCQ Points
🟢 Exocrine glands release secretions via ducts – e.g., salivary, sweat glands
🟢 Pancreas is both exocrine and endocrine – Exocrine part secretes digestive enzymes
🟢 Goblet cells are unicellular exocrine glands producing mucus
🟢 Sweat glands help regulate body temperature and excrete waste
🟢 Merocrine secretion is the most common type (via exocytosis)
🟢 Sebaceous glands use holocrine secretion – entire cell disintegrates
🟢 Mammary glands are modified apocrine glands
