epithelial cells and tissues Flashcards
define tissue
a group or groups of cells whose type, organisation and architecture are integral to its function
tissues are made up of cells, extracellular matrix and fluid
what are the five main cell types?
Connective tissue cells Contractile tissues Haematopoietic cells Neural cells Epithelial cells
give examples of connective tissue cells
fibroblasts (many tissues), chondrocytes (cartilage), osteocytes (bone)
give examples of contractile tissues
skeletal muscle, cardiac muscle, smooth muscle
give examples of haematopoietic cells
blood cells, tissue-resident immune cells, and the cells of the bone marrow from which they are derived
give examples of neural cells
cells of the nervous system having two main types; neurones (carry electrical signals) and glial cells (support cells)
give examples of epithelial cells
cells forming continuous layers, these layers line surfaces and separate tissue compartments and have a variety of other functions
do tumours retain characteristics of the cell type they originate from or not?
yes
what are epithelial cancers called?
carcinomas
what are mesenchymal (connective tissue and muscle) cancers called?
sarcomas
what are haematopoietic cancers from bone marrow cells called?
leukaemia
what are haematopoietic cancers from lymphocytes called?
lymphoma
what are neural cell cancers from neurones called?
neuroblastomas
what are neural cell cancers from glial cells called?
gliomas
how are epithelial cells organised?
epithelial cells make organised, stable cell-cell junctions to form continuous, cohesive layers
epithelial layers line internal and external body surfaces and have a variety of functions, e.g. transport, absorption, secretion, protection
cell-cell junctions key to the formation and maintenance of epithelial layers
how are epithelial cells classified?
their shape
squamous (flattened plate-shape)
cuboidal
columnar
their layering
single layer = simple epithelium
multi-layered = stratified epithelium
where are single squamous epithelia found?
These arrangements are found in the lung alveolar (air sac) epithelium, mesothelium (lining major body cavities), endothelium lining blood vessels and other blood spaces)
what is the function of single squamous epithelia?
They form a thin epithelium that allows exchange to occur (e.g. gas exchange in the alveoli).
where are simple cuboidal epithelia found?
These epithelial cell arrangements are typical of the linings found in ducts
e.g. those lining the kidney collecting ducts.
where are simple columnar epithelia found?
surfaces involved in absorption and secretion of molecules.
e.g. enterocytes lining the gut, involved in the take up of the breakdown products of digestion
what are the 2 types of stratified squamous epithelia?
keratinising
non-keratinising
outline keratinizing epithelia
Epithelial cells which produce keratin and in doing so die becoming thicker, stronger, protective structures (e.g. epidermis (skin epithelium). Such cells lose their cellular organelles and nuclei, not visible under light microscopy.
outline non keratinizing epithelia
Epithelial cells which do not undergo keratinisation. They retain their nuclei and organelles. (e.g. epithelium lining the mouth, oesophagus, anus, cervix and vagina.
what is pseudo stratified epithelia?
This epithelium appears to be multi-layered.
On close examination, the surface cells have contact with the basal lamina.
