Which of the following glands in human body acts both as an endocrine gland as well as an exocrine gland ?

Question

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Correct — C, Pancreas. The pancreas is the textbook heterocrine (mixed) gland. The overwhelming bulk of it is exocrine: acinar cells make pancreatic juice — pancreatic amylase, lipase, nucleases and the protein-digesting zymogens trypsinogen and chymotrypsinogen, together with bicarbonate from the duct cells — which drains through the pancreatic duct and is poured into the duodenum, i.e. delivered through a duct onto an epithelial surface. Scattered through that same tissue are the islets of Langerhans, only about 1–2% of the organ's mass, whose alpha cells secrete glucagon, beta cells insulin and delta cells somatostatin directly into the bloodstream with no duct at all. One organ, both modes of secretion — which is exactly what the question asks for.

Why the other options are wrong — (a) Purely endocrine and completely ductless. The cortex releases aldosterone, cortisol and small amounts of androgens; the medulla releases adrenaline and noradrenaline — all straight into the blood. It has no secretory duct and no exocrine product.  (b) Purely exocrine. It produces tears and delivers them through lacrimal ducts onto the surface of the eye. It secretes no hormone into the bloodstream, so it fails the endocrine half of the question.  (d) Purely endocrine. Follicular cells release thyroxine (T4) and triiodothyronine (T3) and the parafollicular C cells release calcitonin, all into the blood. The colloid held inside the follicles is an internal store, not a duct-borne secretion, so the thyroid is ductless.

Concept: Glands are classified by where their product goes. An exocrine gland pours its secretion through a duct onto a body surface or into a cavity (sweat, saliva, tears, digestive juices). An endocrine gland is ductless and releases hormones into the bloodstream. A few organs do both and are called heterocrine or mixed glands — in the human body the pancreas is the standard example, and the liver and the gonads (testis and ovary) also combine the two functions.

State PCS 2019 Q16 — Science & Technology PYQ with Answer

State PCS 2019 Q16 — Science & Technology PYQ with Answer