Epithelia Flashcards
Epithelia
Definition, functions, location(s)
Cells forming borders between other tissues and gas or liquid.
* Protects other tissues
* Controls movement of materials between fluid and other tissues by secretion
* Cells are held tightly together in a continuous sheet
Skin - linging of digestive tract - blood vessels - urinary tract
Polarity in epithelial tissue
Refers to epithelial with two sides: Apical + Basal
Apical Side
Definition + location(s)
Top side of polar cells that face towards fluid, has air in the lumen and often have silica or microvili (lungs, digestive tract)
Basal Side
Bottom side of polar epithelial that sit above the basement membrane.
Basement Membrane
Definition, functions, location(s)
Sits between basal + connective tissue.
Forms a scaffolding for epithelial cells to grow on.
Top layer - epithelial
Bottom layer - cells in connective tissue
Lumen
Any hallow space in the body.
Are there blood vessels in epithelia?
No
Underlying connective tissue diffuses nutrients and oxygen from the blood.
How to classify epithelial tissue…
- # of layersa. Stratified - multi layer - doesn’t touch basement membrane
b. Simple - single layer - touches basement membrane - By shape
a. Squamous - flat
b. Cuboidal - square looking
c. Columnar - cylindrical / rectanglular
Simple Squamous
Definition, functions, location(s)
Single layer flat cells
* thin enough for diffusion
* alveoli in lungs
* capillaries - smallest blood vessels
Mesothelia
Line ventral body cavities –> part of serosa
Endothelia
Lines blood vessels, chambers of the heart + lymph vessels
* Only tissue that blood touches
Stratisfied Squamous
Definition, functions, location(s)
Many layers flat cells
* Bottom layers are cuboidal
* Flat cells move
* High abrasion locations susceptible to shedding
Skin, vaginal walls, mouth
Simple Columnar Epithelia
Definition, functions, location(s)
Single layer cylindrical cells
* Controls movement of nutrients out from lumen of the digestive tract into tissues
* Mostly in the digestive tract
* Many have microvilli
Transitional Epithelia
Definition, functions, location(s)
Specialized Stratified Epithelia
* Very stretchy by going from Cuboidal –> Flat
* Urinary tract
Pseydostratified Columnar Epithelia
Definition, functions, location(s)
Undercover Simple Epithelia
* All cells touch the base, nuclei are at different heights
Respiratory tract - apical side has silica
