Lect 1 - Epithelia Flashcards
define epithelial cells
Epithelial tissues line the cavities and surfaces of structures throughout the body, and also form many glands.
glandular
it is glandular meaning that it can excrete and secrete material not related to its own metabolic needs
simple v stratified
simple - single
strat - many of them together
describe simple squamous epithelium, what are it main fucntions
squamous epithelium cells (aka pavement epithelium) are flat, wider than it is tall. this makes these cells excellent at exchanging stuff.
- diffusion - e.g. lungs
- filtration - e.g. kidneys
- secretion - e.g. pleural, pericardial, peritoneal cavities
describe simple cuboidal epithelium, what are it main fucntions
these cells are as wide as deep. they are good at secretion and absorption, and protection.
absorption - e.g. lining of kidney ducts
secretory - e.g. saliva and pacreas
describe simple columnar epithelium, what are it main fucntions
these cells are taller than wide, with nucleus located near the base. they can be ciliated and non-ciliated
specialised fucntions get extra bits
in addition absorption, secretion, and protection, ciliated cells also facilitate transportation
e.g. gall bladder
sits on basil membrane
where are simple columnar ciliated epithelium cell found
fallopian tubes
why would simple columnar with microvilli
be useful
microvilli are tiny bunched up projection that increase the relative surface of cells
this is especially useful for absorption. it is mostly found in small and large intestines
what is the role of glycocalyx
extracellular material on the apical side of microvilli that provides additional surface for adsorption and includes enzymes secreted by the absorptive cells that are essential for the final steps of digestion of proteins and sugars.
compare nonmotile and motile processes
nonmotile - cytoplasmic projections that increase SA of cells and facilitate transport in and out of the cell. e.g. taste buds, inner ear
motile - cilia and flagella. facilitate movement of extracellular material
whats a goblet cell
these are modified columnar cells that synthesise and secrete mucus.
they have nucleus at base, and mucigen granules at the apex
they’re mainly found in the small and large intestines
describe pseudostratified ciliated
columnar epithelium, where are they found
looks like more than 1 layer of cell, all cells reset on the basement membrane but nuclei are on different levels
primarily found in bronchus
responsible for secretion lububrication, protecting, and transport
describe stratified squamous epithelium, what do they do
made up of 2 more more layers of squamous cell
they mostly serve protective purpose
what are desmosomes (macula adherens)
dense regions of attachment between cells
strong bonds
describe stratified cuboidal epithelium, where are they usually found
2 or 3 layers of cuboidal epithelium
not much absorption or secretion
usually found in the larger duction of exocrine, e.g. salivary glands
describe stratified columnar epithelium, where are they usually found
this is made from several layers of epithelial cells of which the surface layer is columnar cells
their role is to protect and secrete
they are only found in male urethra and portion of the conjunctiva
describe transitional (urothelial) epithelium, where are they usually found
this is the intermediate transition between stratified cuboidal and stratified squamous
4 to 5 layers of cell
basal layer is cuboidal, surface is large and rounded
protective and distensible
e.g. bladder
differentiate between unicellular and multicellular glandular epithelium
unicellular - goblet
multicellular - endo/exocrine glands
what are the differences between endocrine and exocrine glands
endo - products (hormones) are secreted directly into the blood
exo - products are release onto free surface of skin or open cavities. e.g. sweat glands, salibary glands
functions of epithelium, and where are they found
• Diffusion - alveoli of lungs
• Barrier - skin
• Containment- endothelium - blood-brain barrier
• Excretion- collecting ducts of kidney
• Secretion - breast (milk),skin (sweat) and
gastrointestinal tract (mucous), pancreas (hormones)
• Absorption - small intestine
• Contractility - bladder, salivary glands
• Sensation - taste buds, olfactory epithelium
differentiate between keratising and nonkeratinising squamous epithelium
keratin - tough protective protein which prevents water loss, resistant to friction, and repels bacteria
keratinising - epidermis of skin
non-keratinising - mouth, vagina, esophagus
