Table of Contents
- Glandular Epithelium – What Is it?
- Glandular Epithelium – Structure and Functions
- Frequently Asked Questions
Glandular Epithelium -What Is it?
Glandular epithelium or glandular tissues are the tissues which are involved in production and release of secretory products in the body. It is one of the four major tissues of the human body. The four main tissues are muscular tissues, nervous tissue, connective tissues and epithelial tissues.
It is involved in the secretion of various secretory products such as sweat, saliva, breast milk, hormones, digestive enzymes, etc. Glandular epithelium can be found in secretory portions of the glands, the sweat glands on the skin, endocrine glands, etc. The human body has various glands releasing substances that play an important function.
In a body, glands are of two types, endocrine glands and exocrine glands. They make up glands in the body, some of them include – sweat glands, glands of the intestinal lining, adrenal, thyroid, sebaceous glands, etc.
Glandular Epithelium – Structure and Functions
Structure
On the basis of structure and ducts, glandular epithelium can be divided into two broad types – endocrine and exocrine.
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Exocrine Glands |
Endocrine Glands |
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They secrete their products into ducts. |
They do not have duct systems. |
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They are connected to the covering epithelium via tubular ducts. |
They lose their connection to the epithelium. |
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Made up of secretory units and ducts (one or more). |
The secretions, called hormones, enter the interstitial fluid which is then diffused directly into the body via the bloodstream. |
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They are further divided structurally based on the shape of the secretory unit and ducts (branched or unbranched). |
Histologically, they are of following types – trabecular type, follicular type and disseminated type. |
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They are either unicellular or multicellular; unicellular cells mostly secrete mucus to the apical surface of the lining epithelium. |
It lacks myoepithelial cells and can synthesise hormones. |
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Examples – Salivary glands, sweat glands, and lacrimal glands. |
Examples – Thyroid gland, pituitary gland and the adrenal glands. |
Function
The major function of epithelial tissue is secretion; some other functions are listed below :
- They help in regulating body temperature and maintaining homeostasis with watery mucus released by the exocrine glands.
- They provide protection against microbial invasion and inhibit water loss with oily secretions from the sebaceous glands and the ceruminous glands by lubricating the epithelium covering.
- Helps in digestion by producing digestive enzymes from salivary glands and the digestive glands.
- Helps in regulating overall growth and development of the body with the help of thyroid gland and pituitary glands.
- Helps in regulating the immune system, blood pressure and metabolism with the help of adrenaline glands.
- Production of gametes from ovary and testes that are necessary for sexual reproduction.
Glands are further divided into three different types based on the secretion methods. These are merocrine, holocrine and apocrine. Merocrine is considered the most common type of secretion. It releases secretory vesicles into the extracellular space. The cell remains unaffected by such secretions, whereas the holocrine secretions cause the death of the cell. Lastly, apocrine secretion releases secretory vesicles from the cell membrane with a portion of the cell.
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See more:
- Endocrine System
- List of Endocrine Glands and Functions
- Exocrine Glands
- Difference between Endocrine and Exocrine Glands
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