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Lecture 2: Pt: 2 Epithelial Tissue - Classification - Coggle Diagram
Lecture 2: Pt: 2
Epithelial Tissue - Classification
Covering & Lining Epithelia
Simple
Simple cuboidal
Appearance --> cuboidal or hexagonal boxes, the distance between adjacent nuclei is approx the height of epithelium
Features --> secretion & absorption
Examples --> pancreas ducts, parts of kidney tubes, smaller ducts of many glands
simple columnar
Ciliated
single layer
goblet cells
Examples --> uterine, fallopian tubes, sinuses, central canal of spinal cord, ventricles of the brain
Function -->
Non-ciliated
single layer
microvilli on apical surface
have goblet cells interspersed
Examples --> Lines gut mucosa from stomach to anus, ducts of many glands (e.g gallbladder)
Function --> secretion, lubrication & absorption
Simple squamous
Features:
most delicate epithelium
filtration, diffusion & secretion
Appearance --> thin, flat & irregular (looks like fried eggs)
Examples --> In Bowmans capsule of kidney, lines cardiovascular, lymphatic systems, inside eye, alveoli of lungs, visceral cavity linings, inside blood vessels and inside heart
Mesothelium
lines pericardial, pleural, peritoneal cavities
Endothelium
lines inside of heart and blood as well as lymphatic vessels.
Stratified
Stratified Squamous
Features --> protect against microbes
Appearance --> Layers, cells furtherest from nutrition are thiner & less active
Keratinised
Features --> makes the surface tough & waterproof
Examples --> skin
Non-Keratinised
Function --> protection from abrasion, defence from microbes, require secretion from glands
Examples --> mouth, throat, tongue, esophagus, anus & vagina
Stratified cuboidal
Stratified columnar
Transitional
Pseudostratified
Pseudostratified columnar
Ciliated
Cilia on some cells
secrete mucus (from goblet cells)
Function --> secrete mucus & move it
Examples --> most upper airways
Non-ciliated
no cilia
lack goblet cells
Function -->
Examples --> larger ducts of glands, epididymis
Glandular Epithelia
Multicellular Exocrine glands
3 characteristics
structure of duct
structure of secretory area
relationship between the 2 (above)
8 possible descriptions:
Simple:
If the gland has a duct that does not divide on its way to the gland cells
Simple Alveolar:
Example --> A stage in embryonic development of simple branch glands
Simple Branched Alveolar:
Example --> Sebaceous (oil) glands
Simple Branched Tubular:
Example --> gastric glands, mucus glands of the esophagus, tongue, duodenum
Simple Coiled Tubular:
Example --> Merocrine sweat glands
Simple Tubular:
Example --> intestinal glands
Compound:
A gland is a compound if the gland divides one or more times on its way to the gland cells
Compound Alveolar:
Example --> Mammary glands
Compound Tubuloalveolar:
Example --> Salivary glands, glands of respiratory passages, pancreas
Compound Tubular:
Example --> Mucous glands (in mouth)
Single cell
exocrine glands
independent scattered gland cells
individual secretory cells are called mucous cells (they secrete mucin)
Membrane Modifications (C&L)
Cilia
motile
hair like structures
arise on the apical surface of epithelial cells
move back and forth to propel fluid in one direction
Function --> clear airways by removing mucus
Microvilli
non motile
finger like structures
form the apical surface of epithelia cells
Function --> increase the surface area of the cell & facilitate absorption