Epithelial tissue Flashcards
how many functions of skin are there
7
name all functions of skin
protection
containment
thermoregulation
immunological defences
sensory abilities
communication
appendages
describe protection (functions of skin)
skin resists abrasion and penetration
blocks entry of foreign material, pathogens, UV rays
describe containment (functions of skin)
skin prevents loss of body fluids
skin is waterproof
describe thermoregulation (functions of skin)
controls transfer of heat across body’s surface
facilitates heat retention and dissipation (sweat and temp regulation)
describe sensory abilities (functions of skin)
sensations
touch
hair (air between hair keeps you warm)
describe communications (functions of skin)
skin releases visual and pheromone signals
describe appendages (functions of skin)
hair
nails
sebaceous glands
sweat glands
ALL EPITHELIAL TISSUE…
RESTS ON A BASEMENT MEMBRANE
what is basal lamina
basement memebrane
what doesn’t H&E stain
the BM
can only see it sometimes depends on plane of section (can see more clear in hair and respiratory tract)
what is only below the BM
blood vessels and extracellular space
name the layers of skin
epidermis
dermis
hypodermis
name the stratums (BM and up)
stratum corneum
stratum granulosum
stratum spinosum
stratum germinativum
describe stratum germinativum
layer of columnar cells resting on BM
stem cells - can divide and become themselves or differentiate to layer above
growth is apical (apical level used to name tissue)
describe stratum spinosum
polygonal shape cells
between cells = spines = desmosomes which connect cells together
describe stratum granulosum
cells are becoming flat
have keratohyalin granules that produce keratin
~ 30 day turnover, makes granules, bursts and gives next stratum
describe stratum corneum
stratified squamous keratinized
cells explode and form keratin sheets
what does covering epithelia mean
covers body and organs
name all types of tissue (epithelia)
simple squamous
simple cuboidal
simple columnar
stratified squamous (keratinized and non keratinized)
transitional
pseudostratified columnar
glandular epithelia
what does lamina propria mean
generally describe connective tissue
describe simple tissues
squamous = one layer flat cells
cuboidal = one layer cube shaped cells
columnar = more tall than wide, could have cilia
the way it looks depends on PLANE OF SECTIONNNNN
describe transitional epithelium
covers bladder - cells expand with it
changes shape often
describe pseudostratifed columnar
pseudo = fake, looks stratified but is simple
found in respiratory tract
goblet cells!
describe staining of BM
glucose moiety + periodic acid = aldehyde moiety
PAS reaction
red/fuchsia stain
can see BM
describe composition of BM
proteoglycans
glycoproteins
collagen
layer of reticular fibers (underlies BM)
describe proteoglycans
look like test tube brush cleaner
protein core
50/50 sugar and proteins
glycosaminoglycans = GAGs
describe GAGs
negatively charged and hold water
give ex of proteoglycans
heparan sulphate - synthesized by epithelial cells
describe glycoproteins
10% sugars and 90% protein
protein backbone
3 sugars and modified sugar at end
name types of glycoproteins (3)
laminin
Nidogen-1 (Enactin)
Fibronectin
describe laminin (glycoproteins)
cross shaped
links surface of epithelial cells to BM (helps it stick)
describe Nidogen-1 (Enactin) (glycoproteins)
small glycoprotein
essential component for BM
describe fibronectin (glycoproteins)
adhesive that binds plasma membrane of epithelial cells to heparan sulphate - like glue
describe collagen
part of ECM
stains bright pink
name and describe collagens of BM
type IV = synthesized by epithelial cells
type VII = anchoring filaments (filaments/fibers and anchors)
type III - reticular fibers
how many functions of BM are there
5
name all functions of BM
1 - structural attachment
2 - compartmentalization
3 - filtration
4 - maintain polarity
5 - tissue scaffolding
describe structural attachment (functions of BM)
attachment of epithelial cells to connective tissue
describe compartmentalization (functions of BM)
isolate epithelial cells and muscle cells (tissue types)
bundle and separate stuff
describe filtration (functions of BM)
movement of molecules is partly regulated by ionic charges
important for kidneys (filtration mechanism)
describe helps maintain polarity (functions of BM)
how cells know basal membrane from apical layers
if they don’t know which way is up then they keep dividing and causes problems like skin cancer (when polarity is off)
intermediate filaments = no polarity
describe tissue scaffolding (functions of BM)
helps to scaffold regeneration
need BM to generate and stabilize cells and create upper layers
name and describe all characteristics of epithelial tissues (6)
1- cells are closely associated with little extracellular space
2 - cells are strongly attached via intracellular junctions
3 - lines body surfaces and cavities
4 - specialization - absorption, secretion, sensation and contractility - depends on where tissue is found
5 - cells are polarized
6 - epithelial tissues rest on A BASEMENT MEMBRANE
what is a scar
regrowing BM
discolouration due to melanocytes
