Epithelia Flashcards
What forms epithelium ?
Epithelial cells
What are the 4 tissue types ?
Epithelial
Nervous
Muscle
Connective
What is an epithelium ?
Epithelia form continuous sheets of cells.
Function of epithelia
Act as barriers :
Between the body and external world
Between fluid compartments within the body
How do epithelia transport molecules ?
Via absorptive & secretory processes
Epithelial Cell types
Cuboidal
Columnar
Squamous
Single Layer of cells
Simple epithelium
Basement Membrane
Each cell comes into contact with a basement membrane separating it from the underlying tissue
Cuboidal cells
Same cell height/width
Have a central nucleus
Columnar cells
Cell height is greater than width
Basal nucleus (near the basement membrane)
Squamous cells
Flat cells
Disc shaped nucleus
Simple cuboidal epithelium function
Secretion & Absorption
Simple cuboidal epithelium localisation
(4 places)
Kidney Tubules
Ducts
Secretory portions of small glands
Ovary surface
Simple columnar epithelium function
Absorption
Secretion of Mucus, Enzymes etc.
Simple columnar epithelium types
Ciliated
Non-Ciliated but with microvilli
Simple columnar epithelium localisation (non-ciliated)
Digestive tract
Gallbladder
Excretory ducts
Simple columnar epithelium localisation (ciliated)
Small bronchi
Uterine Tubes
Simple squamous epithelium function
Passage of materials by diffusion and filtration
Secretion of lubricating substances
Simple squamous epithelium localisation
Alveoli of Lungs
Blood Vessels
Lymphatic vessels
Kidney glomeruli
Simple pseudostratified epithelium
Looks like there are multiple layers
All cells are in contact with the extracellular matrix
Several ‘layers’ of nuclei
Simple pseudostratified epithelium types
Ciliated
Non-ciliated
Simple pseudostratified epithelium function
Secretion of mucus
Simple pseudostratified epithelium localisation (non-ciliated)
Large glands
Vas deferens
Simple pseudostratified epithelium localisation (ciliated)
Trachea
Upper respiratory tract
Multiple layers of cells
Stratified epithelium
Stratified cuboidal epithelium function
Protects underlying tissue
Stratified cuboidal epithelium localisation
Largest ducts of sweat glands
Mammary glands
Salivary glands
Stratified columnar epithelium function
Protection and secretion
Stratified columnar epithelium localisation
RARE !
Urethra
Large ducts of glands
Conjunctiva of eyes
Stratified squamous epithelium function
Protects underlying tissue
Stratified squamous epithelium types
Keratinised
Non-keratinised