4-epithelial Tissue Flashcards
A diverse group of cells with an ordered structure working together for a common function
Tissue
4 types of tissue
Epithelial
Connective
Muscle
Nervous
Basic characteristics of epithelial tissue
- Covers body surface, lines body cavities and form glands (skin, airways, digestive lining and urinary tract lining)
- Closely packed cells- little extracellular materials
- Cells are joined by specialized cell-to-cell junctions
• Basement membrane
• Separates epithelium from underlying connective tissue
• It is a non-cellular membrane comprised
of polysaccharide rich membrane
• Acts as a sieve to prevent materials from
entering the body
Avascular- cells completely lack bloody supply
Highly regenerative
Free surface is the apical side and the bound surface is the basolateral side
Epithelial Tissue
Function 1 of epithelial tissue
• Secretion: Eg. Digestive tract involved in high secretion activity
Function 2 of epithelial tissue
• Selective absorption: First contact with materials and allow them to be
absorbed
Function 3 of epithelial tissue
• Protection: Specialized epithelium to protect internal tissues including connective tissue (Eg. Skin)
Function 4 of the epithelial tissue
• Transcellular transport: Specialized cells aid the movement of
substances from cell to cell through a certain distance (Eg. Mucus)
Function 5 of epithelial tissue
• Detection of sensation: First layer with outer environment to detect
sensation along with nerve cells
Epithelial cell shapes
Squamous
Cuboidal
Columnar
Epithelial layers
Simple
Stratified
Pseudostratified
Transitional
Epithelial tissue specialization
Keratin
Microvilli
Cilia
Simple squamous epithelium
- Make up the alveoli (air sacs of the lung
- Make up the lining of all blood vessels and capillaries (endothelium)
- Make up various membranes within the body (peritoneum)
- Glomerulus of kidney
Simple cuboidal epithelium
- Make up the collecting tubules of the kidney, liver, pancreas, thyroid and other glands of the body
- Synthesis of hormones and secretion
Simple columnar epithelium
ciliated
Makes up the lining of the ovary ducts (fallopian tubes)
Simple columnar microvilli epithelium with goblet cells
Makes up the lining of the intestine (secrete mucus)
Stratified squamous epithelium
Located in areas of body subjected to abrasion
Stratified squamous epithelium
- Keratinizing Stratified squamous epithelium- Skin
* Non-keratinizing Stratified squamous epithelium- tongue, oral mucosa, esophagus, vagina
Stratified cuboidal epithelium
Secretes sweat, ovarian hormones and sperm
Stratified cuboidal epithelium
Sweat glands, salivary glands, ovarian follicles and seminiferous tubules
Stratified columnar epithelium
Are rare. Located in the largest ducts of salivary glands (parotid, submandibular).
Stratified columnar epithelium
The basal layer of cells are cuboidal cells and the layer nearest the apical surface includes columnar cells. The large droplets are mucus, in Goblet cells.
This also illustrates the fact that epithelia are classified according to the cells nearest the
Lumen
Pseudostratified columnar ciliated epithelium with goblet cells:
- Makes up the lining of the respiratory tract
* Secrete mucus, move mucus, trap foreign particles
Transitional epithelium
Makes up the lining of the urinary bladder and the ureter
Transitional epithelium
Stratified tissue becomes stretched as the urinary bladder becomes filled with urine (distention)
