Types of Glandular Epithelium
There are two types of glandular epithelium –
1. Endocrine
2. Exocrine
Check out here types of membranous epithelium.
1. Endocrine
Endocrine are ductless glands. It secreted hormones into the surrounding interstitial fluid then diffuses into the blood and carried to various organs and tissues within the body.
Endocrine glands include -
1. Hypothalamus gland
2. Pituitary gland
3. Pineal gland
4. Thyroid gland
5. Parathyroid gland
6. Thymus gland
7. Adrenal gland
8. Pancreas gland
9. Gonads- ovaries (in female), testes (in a male)
2. Exocrine
Exocrine Gland secretes their products (hormones) into ducts that empty onto the surface of covering and lining epithelium. The product of the exocrine gland may be released onto the skin surface or into the lumen of a hollow organ.
Secretions of exocrine glands include –
1. Mucus
2. Perspiration
3. Oil
4. Wax
5. Digestive enzyme
For example,
1. Sweat gland
2. Salivary gland
3. Lacrimal gland
4. Mammary gland
5. Pancreas (juice)
6. Liver (bile)
Classification of Exocrine Gland
Classification of exocrine glands-
A. Structural Classification of Exocrine Glands
1. Depending upon the number of cells
a. Unicellular gland
For example; Goblet cells
Location
Epithelium lining of digestive, respiration, urinary and reproductive system
Function
Produce mucus to lubricate the surface of this tissue.
b. Multicellular gland
Many glands occur in different forms.
For example; Salivary gland
2. Depending upon types of duct
a. Simple gland
Only one unbranched duct.
For example; Intestinal gland
b. Compound gland
With a branched duct system like a tree trunk.
For example; mucous gland of the mouth,
Bulbourethral glands or Cowper’s gland (male sex organ)
3. Depending upon shapes of secretory portion of the gland
a. Tubular glands
Secretory portion is straight tubular.
For example, Intestinal gland (simple gland),
Mucous gland of mouth,
Bulbourethral gland (compound gland)
b. Alveolar glands/ Acinar glands
Secretory portion of the gland is round.
For example- Seminal vesical gland (simple gland),
Mammary glands (compound glands)
3. Tubuloalveolar glands
Secretory portion both tubular and alveolar shapes.
For example- salivary gland,
Glands of respiratory passage,
Pancreas (compound gland)
4. Coiled tubular gland
Secretory portion of the gland is coiled.
For example- Sweat gland
B. Functional classification of Exocrine glands
1. Depending upon the type of secretions
a. Mucus glands
Secrete thick mucus.
b. Serous glands
Secrete thin, watery substances, generally contain enzymes.
c. Mixed glands
Contain both mucus and serous cells that produce serous and mucus secretion.
2. Depending upon how they release their secretions
a. Meocrine glands
Release secretion without breaking plasma membrane, using process exocytosis.
For example- Pancreases release the digestive enzyme
b. Holocrine glands
Secretions are released by the rupture of the plasma membrane, which destroys the cell, Cell dies and is discharged with its contents as glandular secretion into the lumen. They accumulate secretory production in the cytosol of the cell.
c. Apocrine gland
These glands collect their secretory materials near the apex or tip of the cell and then release them into the duct by pinching off the distended end, causing loss of cytoplasm cells. Recovery and repair of a cell are rapid. Continuous secretion occurs and their secretions usually have an odor.
For example- Mammary gland.
Get here details on connective tissue and muscle tissue.
0 Comments