Biology · Chemical Coordination and Integration · NEET
| Duct | Absent (ductless) | Present (has a duct) |
| Secretion goes to | Directly into blood/lymph | Onto a surface or into a cavity |
| Product | Hormones | Enzymes, sweat, saliva, bile, milk |
| Reach of action | Distant target organ (whole body) | Local, near the duct opening |
| Example | Thyroid, pituitary, adrenal, pineal | Salivary, sweat, sebaceous, liver |
Yes. Endocrine glands have NO ducts, so they are called ductless glands. Their secretions (hormones) are poured directly into the blood or lymph around them. The blood then carries the hormone to a far-away target organ. This is why hormones act slowly but reach the whole body. Examples: thyroid, pituitary, adrenal, pineal.
The pancreas is a heterocrine (mixed) gland. Its Islets of Langerhans act as ENDOCRINE tissue, releasing hormones insulin and glucagon into the blood. The rest of the pancreas (acini) acts as EXOCRINE tissue, sending pancreatic juice (digestive enzymes) through the pancreatic duct into the small intestine. So one organ does two jobs. NEET loves this example.
Hormones are made by endocrine glands and travel in blood to control distant organs (they are chemical messengers, not consumed in reactions). Enzymes are often exocrine secretions (like from salivary glands or pancreatic acini) that are carried by ducts to a specific site to break down food. Hormones signal; enzymes digest.
No. Exocrine glands make products like sweat, saliva, mucus, milk, tears, oil (sebum), and digestive enzymes. These leave through a duct onto a body surface or into a cavity. Only endocrine glands (or the endocrine part of mixed glands) make hormones that enter the blood.
The liver is mainly an EXOCRINE gland because it secretes bile, which travels through the bile duct to the intestine. It is not counted as a classical endocrine gland, though it does release some factors into blood. For NEET, remember bile = exocrine secretion through a duct.
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Endocrine glands are ductless and release hormones into the blood; exocrine glands have ducts and release secretions onto a surface or into a cavity.
Endocrine glands are ductless. Examples include the pituitary, thyroid, parathyroid, adrenal, pineal, and thymus.
Salivary glands, sweat glands, and sebaceous (oil) glands. The liver (bile) and mammary glands (milk) are also exocrine.
The pancreas is a mixed (heterocrine) gland: endocrine through the Islets of Langerhans (insulin, glucagon) and exocrine through the acini (digestive enzymes).
Endocrine secretions (hormones) usually act slowly because they travel in blood, but their effect is widespread and often long-lasting compared to nerve signals.
