Epithelial Cells and Tissues Flashcards
What is the breakdown of the formation of an organism?
Group of cells -> Tissues
Group of Tissues->Organ
Group of organs _> organ systems
Group of organ systems-> organism
What are tissues?
Groups of cellls whose type, organisation and architecture is integral to its function
made up of cells, extracellular matrix and fluid
What is the ECM?
material deposited by cells which forms the insoluble part of the extracellular environment
What is ECM generally composed of?
fibrillar (or reticular) proteins such as, collagens or elastin, embedded in a hydrated gel with proteoglycans or/+ ground substance)
Organisation of ecm?
depends on where : poorly in places such as loose connective tissue or highly in bone, tendon and basal lamina
What are the main cell types?
HECCN: Haematopoietic cells Epithelial Cells Contractile tissues Connective tissue cells Neural cells
What are connective tissue cells?
cells such as fibroblasts found in many tissues
Chondrocytes - cells that make cartilage and osteocytes - make bone
What are contractile tissues?
skeletal muscle, cardiac muscle, smooth muscle
What are haematopoietic cells?
blood cells, tissue resident immune cells and cells of bone marrow from which they are derived
What are neural cells?
cells of nervous system:
Neurones that carry electrical charge
glial cells = support cells
What are epithelial cells?
cells forming continuous layers within organs. line various surfaces and separate tissue compartments and have a variety of other functions
Cancers of epithelial tissues are called what?
carcinomas
what is a sarcoma?
cancer of connective tissue and muscle
What are leukaemias or lymphomas?
haematopoietic cancers
from bone marrow cells
lymphocytes
What are neural cell cancers called?
Neuroblastomas from neurones or gliomas from glial cells
How are epithelial cells organised?
They make organised, stable cell junctions to form continuous, cohesive layers
cell to cell junction = imp in forming and maintaining layers
What are ep cells really important for?
lining internal and external surfaces
and
transport, absorption e.g. enterocytes have specialised ep cells for this, secretion, protection
What are the two main criteria of epithelial cell classification?
shape and layering
What are the varieties of shapes?
squamous
cuboidal
columnar - column like
What are the varieties of layers in epithelial cells?
Single layer = simple epithelium
Many layers = stratified
What is squamous?
shape characterisation: (flattened plate-shape)
What is columnar?
Arranged in columns (shape)
What is cuboidal?
cube like - shape
Where is simple squamous epithelium found?
lung alveolar (Air sac) epithelium, mesothelium (lining major body cavities) endothelium (lining bv and other blood spaces)
what does the thin epithelium formed by a simple squamous layer allow?
exchange, e.g. gas exchange in alveoli
Where are simple cuboidal epithelium found?
typical linings found in duct e.g. lining kidney collecting duct
What are the simple columnar ep cells typically found in/on?
surfaces involved in the absorption and secretion of molecules
also much more elongated
What are the two types of stratified squamous epithelium?
Keratinizing
non-keratinizing
What are keratinizing epithelium?
1 of the stratified squamous type:
epithelial cells which prod keratin and in doing die becoming thicker, stronger, protective structures e.g. epidermis - skin epitheium.
they lose their cellular organelles and nuclei, which are not visible under light microscopy
What are non-keratinizing epithelium?
ep cells that do not undergo keratinisation. retain nuclei and organelles e.g. epithelium lining mouth, cervix, anus, oesophagus, vagina
are all the cells in stratified squamous epithelium the same?
no, cell shapes vary in the various layers. the squamous is only related to the surface of the cell
Why is keratinising epithelium beneficial?
can form thick layers that protect underlying tissues from various things such as heat, cold, solvents (alcohols), abrasion etc. (phys and chem)
what are pseudo-stratified epithelium cells?
appear to be multi layered but are single. on close examination the surface cells have contact with the basal lamina.
pseudo means fake
Where are pseudostratified epithelium found?
airway - epithelium of trachea and bronchi, various ducts in urinary and reproductive tracts
What is an epithelial cell membrane organised into?
domains: apical and basolateral
Are epithelial functions random or not?
most are directional so are highly organised and NOT random e.g. secretion, fluid and solute transport and absorption
What is required for directionality needed for epithelial function?
epithelial polarity which is seen as different regions of the cell surface being different from one another with discretely organised cellular contents
Where is the apical domain?
apical at lumenal (open) surface / above junction
Where is basolateral domain?
basolateral everything below junction
basal surface is in contact w the ecm
lateral membrane is what opposes the adjacent cell
