The Exocrine glands Are glands that release secretions by means of a conduit that opens on a Epithelial surface .
Our body has two types of glands, the endocrine glands and the exocrine glands. The exocrine glands are mostly identified as the glands that hold the ducts on the surfaces of the body.
The endocrine glands, on the other hand, are called glands without ducts, because in the process of development, these glands lose their contact or union with the embryological ducts or surfaces and remain as blocks of tissue in the body.
It has been discovered that both glands secrete substances like enzymes, hormones, metabolites and other molecules. The cellular products of the exocrine glands are collected in the duct and moved to the surface when the duct is in contact with the surface.
In addition, the exocrine glands include the sweat glands, sebaceous, mammary glands, and glands that secrete digestive enzymes. Most of the glands of the body are of the exocrine type.
Types of exocrine glands
Exocrine unicellular glands
They consist of unique cells, special for the secretion, that intermingle among others epithelial cells Not secretory.
Although unicellular, they lack ducts, they are nevertheless considered exocrine because they secrete their products directly on the free surface of the open cavities of the body.
The most common unicellular exocrine glands are goblet cells (mucus secreting cells) found in the epithelium of the trachea and the digestive tract.
Multicellular exocrine glands
They are formed by invagination or bagging, of an epithelial lamina. The epithelium grows from the surface to the underlying tissues to form a single or composite tube. The blunt end of the tube forms the secretory parts of the gland and may remain tubular or expand to form rounded sacs called acini or alveoli.
What are the different modes of secretion in the exocrine glands?
There are three different ways in which the exocrine glands secrete their products. These modes of secretion are called merocrine, apocrine and holocrine.
- The Merocrine glands (Eg, salivary glands) secrete their product from intact cells.
- The Apocrine glands (Eg mammary glands) accumulate their secretory product on the apical surface of each cell, which then separates from the rest into a secretion in the lumen of the gland. The cells repair themselves.
- The Holocrine glands (Eg, oil or sebaceous glands) are those in which whole cells and their secretions accumulate as the secretory product of the gland. The discharged cells are replaced by new ones.
Examples
Some of the prominent examples of the exocrine glands are:
- Salivary glands, which are a type of merocrine glands and secrete saliva.
- Glands present in the liver for the production of bile.
- Prostate gland
- Glands in the pancreas that secrete pancreatic fluid.
- Gastric glands.
- Sweat glands.
What are endocrine glands?
The glands of the endocrine system Secrete hormones into the bloodstream to maintain Homeostasis And regulate metabolism.
He Hypothalamus And the pituitary gland are the command and control centers, directing the hormones to other glands and throughout the body.
Other primary endocrine glands, such as the thyroid and parathyroid glands, the adrenal glands and the pineal gland, adjust the levels of various substances in the blood and regulate metabolism, growth, the sleep cycle, and other processes.
Organs like the pancreas also secrete hormones as part of the endocrine system. Secondary endocrine organs include the gonads, kidneys and thymus.
On the other hand, the hormones regulate the internal functions from the metabolism And growth to sexual development and induction of birth.
They circulate through the bloodstream, bind to cells, and adjust the function of whole tissues and organs.
It all starts with the hypothalamus and pituitary gland, the owners of the endocrine system. The releasing hormones control the secretions of the other endocrine glands and most of the endocrine functions.
Through the body, hormones allow reactions to stress and other external changes and keep the regular processes working.
References
- Endocrine Glands and Types of Hormones (s.f.). Hormone.org
- Glands of the Human Endocrine System (s.f.). Ivyroses.com.
- Exocrine Glands (January 2002). Biology-pages.info.
- Exocrine gland (s.f.). Sciencedaily.com.
- Exocrine Glands - Structural Classification, Functional Classification (s.f.). Science.jrank.org.
- Glands (s.f.) mhhe.com.