I came across this idea while reading an excerpt of my textbook $-$

Muscles move eye lid , tongue, beat the heart, popel food through gut, discharge wastes, squeeze out secretion from the glands etc.

But I don't understand how this happen ? Does glands really squeeze out hormones?


1 Answer 1


No they are not made of muscles. Glands are modified epithelial tissues. Glands are basically of two types Endocrine and Exocrine glands.

  • Endocrine gland

It is a gland that lacks a duct system. The secretions are directly poured into the bloodstream. They secrete hormones through exocytosis mostly.

  • Exocrine gland

It is a gland with a duct system. The secretions(sweat, sebum,saliva etc) are transported onto a surface of the body (e.g skin or lumen of GI tract) by ducts.Exocrine glands may be controlled by muscles at the duct level.

There are three types of exocrine glands based on the process of secretion of chemical substance at a cellular level$-$

  • Apocrine gland

It is a gland in which the apical portion of the secretory cells are distintegrated to release the chemical. e.g- Apocrine sweat gland

  • Holocrine gland

It is a gland in which the secretory cells are completely disintegrated to release the chemical.e.g.- Sebaceous gland

  • Merocrine gland

It is a gland in which the secretory cells remain intact and the chemical is released through exocytosis.e.g.- salivary gland

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