Epithelial Tissue Flashcards
Define epithelial tissues.
The tissue that form the covering of the body externally as well as the internal covering of some organs and body spaces inside it.
What is the characteristic feature of epithelial tissue?
There is no intercellular space, cells joined together by carbohydrate derivatives, and cells resting upon avascular basement membrane.
What are the types of epithelial tissues?
- Simple epithelial tissue
- Compound/Stratified epithelial tissue
- Modified epithelial tissue
What are simple epithelial tissues?
The tissue having single layered arrangement of cells.
What are the types of simple epithelial tissue?
- Simple squamous
- Simple Cuboidal
- Simple Columnar
- Pseudostratified
What is simple squamous tissue also known as?
Pavement epithelium/Tessellated epithelium
Location of Simple Squamous Epithelium
covering of buccal cavity, coelom of large intestines, alveoli of lungs, capillaries, blood vessels, glomerulus of kidney.
What are the squamous epithelium in blood vessels called?
Endothelium
What are the squamous epithelium in coelom called?
Mesothelium
Location of Simple Cuboidal Epithelium.
kidney tubules, sweat glands, thyroid glands, germinal epithelium of ovary and testis, salivary glands, choroid, iris, retina of eye.
What are the two types of cuboidal epithelium?
- Ciliated Cuboidal- goblet cells, bronchioles, ducts of nephrons
- Brush-bordered Cuboidal- Proximal Convoluted Tubules (PCT)
Location of simple columnar epithelium.
Gall bladder, small intestinal glands, goblet cells of stomach, ureter and uterine wall, bile duct, pancreatic lobules, inner lining of alimentary canal
What are the two types of simple columnar epithelium?
- Ciliated columnar- oviduct, bronchioles
- Brush bordered columnar- microvilli of small intestine
What is pseudostratified epithelium? Why is it called so?
The simple epithelial tissue that appears to look stratified due to unequal size of cell resulting their free surface to be on different levels gives false multilayered appearance.
Location of Pseudostratified.
trachea, large bronchi, nasal epithelium, epididymis, vasa differentia, urinary duct.
What are the stratified epithelial tissues?
The multilayered epithelium with inner germ layer and outer layers.
What is stratified squamous epithelium?
Epithelium with inner cuboidal germ cell and upper layer of squamous cell.
What are the types of stratified squamous epithelium?
- Keratinized/Cornified Epithelium- Hair, Nails, Claws, Skin
- Non-Keratinized Epithelium- Vagina, Cervix, buccal cavity, anus
Stratified Cuboidal Epithelium
Inner layer of germ cell(cuboidal or columnar) and outer layer of cuboidal cells.
Locations of Stratified Cuboidal Epithelium
Inner linings of ducts Sweat glands, Salivary glands, mammary glands, pancreatic duct and female urethra.
Locations of Stratified columnar epithelium
linings of ducts of mammary glands, larynx, trachea, vasa differentia, conjunctiva of eye.
What are transitional epithelium?
Also known as urothelium they lack basement membrane and has stretchable quality.
Upper layer- dome shaped
Lower layer- club shaped
Location of transitional epithelium
Urinary bladder, Urethra, uterus and ureter
What are the modified epithelium?
The epithelial tissues that have been modified for special functions is called modified epithelium.
What are they usually composed of?
Cuboidal or columnar cells
What are the types of modified epithelium?
- Ciliated epithelium
- Sensory Epithelium
- Germinal Epithelium
- Glandular Epithelium
Location of ciliated epithelium
skin, uriniferous tubules, sperm ducts, trachea, bronchi, oviduct.
Location of sensory epithelium
lining of nasal cavity, tongue, internal ear, retina of eye
Location of germinal epithelium
- Inner linings of testes and ovary
What are glandular epithelium?
The epithelium modified such that it secretes chemical substances essential for the body such as hormones and enzymes.
Types of gland on the basis of number of cells.
- unicellular gland - secretory goblet cell
- multicellular gland- swear gland, gastric glands etc.
Types of gland on the basis of presence of ducts.
- endocrine glands - ductless glands, producing hormones : pituitary, thymus, thyroid, adrenal gland
- exocrine glands- ducted glands, producing enzymes: tear gland, salivary gland, sweat gland.
- heterocrine glands/mixed glands- testes, ovary and pancreas
Types of gland on the basis of mode of secretion.
- merocrine- no damage to cell (goblet cell, salivary gland, intestinal gland, sweat gland and pancreatic gland
2.apocrine gland-loss and damage to some part of cell( mammary gland, molls gland of eye)
3.holocrine gland-loss of whole cell(Sebaceous gland)
Types of glands on the basis of shape and structure
- simple glands
- compound glands
Simple glands
single unbranched duct
a. simple tubular gland-intestinal crypts in intestine
b. simple coiled tubular gland- sweat gland
c. simple branched tubular gland-gastric and Brunner’s gland
d. simple alveolar gland-mucus secreting gland of frog
e. simple branched alveolar gland- oil glands
Compound glands
having branched duct
a. compound tubular- salivary gland, testes and exocrine part of pancreatic duct
b. compound alveolar-
mammary and pancreatic
c. compound tubulo-alveolar gland
cowpers gland, salivary and mammary gland
Types of glands on the basis of secretions
- mucous- mucus secretion - goblet cells
2.serous- serous fluid- parotid salivary, intestinal and sweat gland - mixed - both mucocyte and serocyte- gastric and pancreatic secretion
