| What epithelia is shown | Stratified columnar |
| what epithelia is shown | Simple squamous |
| What epithelia shown | Stratified squamous |
| Features of simple squamous epithelium | Thin, scale-like flat cells
Single layer
All rest on the basement membrane
Nuclei bulge from cell surface |
| Function of simple squamous epithelium | Lubrication to allow movement of viscera
Gas exchange ( alveoli )
Barrier ( Bowman's capsule )
Passive transport of water
Active transport |
| Where can simple squamous epithelium be found | Lining of blood and lymph vessels (endothelium)
Bowman's capsule
Loop of henle
Inner and middle ear
Intercalated pancreatic ducts |
| Features of simple cuboidal | Equal width and height
Centrally places round nucleus
Rests on basement membrane
May or may not feature brush border of microvilli |
| Location of simple cuboidal epithelium | Thyrocytes
Mesothelium of ovary
Small ducts of many exocrine glands
Kidney tubules
Respiratory bronchioles |
| Function of simple cuboidal | Secretion
Absorption
Conduit
Barrier
Hormone synthesis and mobilisation |
| Features of simple columnar | Rectangular
Oval basal nucleus
Rests on basement membrane |
| Where is simple columnar found | Small intestine and colon
Gallbladder
Striated duct of salivary gland |
| Function of simple columnar found | Secretion
Absorption
Conduit
Transport |
| Pseudostratified squamous epithelium features | Some tall some short
Nuclei found in basal 2/3rd
Some have cilia |
| Psuedostratified squamous epithelium is found where | Nasal cavity, trachea, Bronchi
Auditory canal inter lobular duct of parotid gland
Lacrimal sac
Epididymis
Parts of the male urethra |
| Psuedostratified squamous epithelium function | Secretion
Absorption
Conduit
Particle trapping --> cilia associated |
| Stratified squamous epithelium (non-keratinized) features | Arranged in layers Basal cuboidal or columnar cells
Flattened cells are replaced by proliferation and differentiation of basal cells |
| Stratified squamous epithelium location ( non-keratinised ) | Oral cavity
Oesophagus
Larynx
Vagina: Secrets glycogen which is a substrate for the formation of lactobacilli
Anal canal
Surface of cornea |
| Stratified squamous epithelium function | Protects against abrasion and water loss
Secretion |
| Stratified squamous epithelium (keratinized) features | 5-6 layers Basal cuboidal cells
Upper layer consists of flattened, dead, anuclear, keratinized cells |
| Where stratified squamous epithelium keratinised location | Skin |
| Function of stratified squamous epithelium keratinised | Protects against UV light rays
Abrasion and water loss |
| Transitional epithelium features | Relaxed = Appears 4-5 layers thick
Basal layer cuboidal
Intermediate layer larger, polygonal
Surface dome- like/rounded/umbrella shaped |
| Transitional epithelium locations | Renal calyces
Ureters
Bladder
Proximal urethra |
| Transitional epithelium function | Distensibility
Protection of underlying tissue from cytotoxic effects of urine |
| What are the different intercellular junctions | Tight junctions ( zona occludens )
Spot junctions ( Demsomes or musculae adherens )
Adheren junctions
Hemidesmosomes |
| Features of Tight junctions | AKA zona occludens
Basically contain occludens and also connect microfilaments of adjacent cells and aim to control diffusion in apical regions
Found closest to the epithelium |
| Features of Adheren junctions | Connect microfilaments of adjacent cells |
| Features of spot junctions | AKA desmosomes or musculae adherens
Comprised of integrins and provide continous epithelium
Anchored by intermediate filaments |
| Features of hemidesmosomes | Anchors cells the the BM by integrins |
| What are Junctional complexes | These isolate the luminal space from the intercellular space
Fluid is moved from e.g. the intestinal lumen into the cell, then into the intercellular space, and finally across the basement membrane into connective tissue and vasculature
Cholera can disrupt this complexes leading to increased intestinal permeability |
