single layer of flattened cells

location: mesothelium, endothelium, alveoli, bowman's capsule, loop of henle

function: exchange; sites of fluid, metabolite or gas exchange

single layer of cuboidal cells

locations:

ducts of certain glands

lining some kidney tubules

functions:

conduit in ducts of glands

secretion in thyroid gland

absorption in kidney tubules

single layer of columnar cells

location:

certain glands

digestive tract

functions:

a conduit in the ducts of certain glands

secretes mucus in cervix

absorptive and secretory in lining of intestine

(intestinal enterocytes absorb nutirents and goblet cells secrete mucus)

free surface cells are squamous while underlying cells show a variety of shapes

two types: 

keratinized: surface cells are dead, lack nuclei and are filled with keratin protein

location: most of exposed surface of body (not cornea or oral cavity)

function: protection against abrasion, dessication, infection and keratin adds waterproof resiliency to epithelium

Nonkeratinized: surface cells are viable

location: moist surfaces subject to wear and tear but do not have an absorptive function (mouth, pharynx, esophagus, vagina, urethra)

function: protection

single layer of cells with varying heights and buclei at diff levels

location: repiratory tract and reproductive tract

Function: lining, secretion, absorption

usually only 2 layers

location: ducts of some glands

Function: lining

rare form of epithelia

apical cells are columnar but underlying cells tend to be cuboidal

location: portions of ducts

function: lining

surface cells are domed shaped or flattened depending on the fuctional state

location: urinary system, kidney, pelvis, ureter, bladder

function: stretches to accomodate urine and prevents water loss to concentrated urine

zonula- belt

occludens- closure

tight junctions, provides tight seal to prevent leakage in intestines and brain

desmosomes

spot welds found in stratified squamous epithelia to guard agains wear and tear

communicating junctions

channels bridge the gap between cells allowing for passage of ions and electrical signals from one cell to another

microscopic fingerlike projections of the cells plasma membrane and cytoplasm...supported by a core of fine actin filaments

(stereocilia are just very long microvilli located in epididymis)

location: striated border of intestines, brush border of kidney and sterocilia of the epididymis

function: increase the surface area for secretion and/or absorption

motile

membrane coveringa 9+2 arrangement os microtubules

each has a basal body for attachment

flagella are similar to cilia

location: trachea and fallopian tubes

mechanical protection

protection from dehydration

selective absorption

secretion and lubrication

digestion

transport

exrcetion

sensory reception and transduction

reproduction

types of epithelia

surface epithelia (simple, stratified, psuedostratified // squamous, cuboidal, columnar, transitional)

gladular epithelia

special epithelia

cover external surface of body, lines all passages that connect with outside (digestion, respiratory, urogenital), lines all coelomis cavities (pleural, pericardial, peritoneal), lines cardiovascular channels (blood vessels and heart endothelium)