Epithelium Flashcards
What is epithelium?
Tissue which covers and lines tissues
What is endothelium?
Epithelium like tissue that lines the cardiovascular system
Where is epithelium found on the interior of the body?
Oral cavity
Alimentary Canal
Respiratory Tract
Genitourinary Tract
Where is epithelium found on the exterior?
Exterior surfaces e.g epidermis of skin
What is mesothelium?
Epithelial like tissue that lines internal closed cavities
Where is epithelium found in the body?
Glands and ducts
What is the function of the epithelium?
Form continuous sheets that act as boundaries between environment surface and teh underlying tissues
Cell proliferation for repair and renewal
Transport of ions solutes and molecules across epithelium surface
Protection
Absorption
Secretion
Sensory perception
What are the features of the epithelium?
Cells are contiguous Cells are polarised no intracellular substances apical membranes face a free surface basal regions lie on a basement membrane epithelia are usually avascular
What is the name given to one cell layer of epithelium?
simple
What is the name given to 2 or more layers of cells
Stratified
What are the 3 different shapes of epithelium cells?
Squamous
Cuboidal
Columnar
What are the 3 differetn surface specialisations?
Cillia
Microvilli
Keratin
What is the role of Simple squamous cells?
Facilitate passive diffusion of gases or fluids
Describe the features of a simple squamous epithelial cell?
So thin that cant see much cytoplasm and nucleus looks like a fried egg
Where are simple cuboidal cells found?
Lines small ducts and tubules
What is the function of simple cubodial cells?
Have excretory secretory and absorptive functions
What is the function of simple columnar cells?
Absorption and secretion
What are pseudostratified columnar cilliated cells?
Appears as many layers due to nuclei being at different levels but all cells make contact with the basement membrane
Where are the microridges on the SSNK and what do they do?
On apical surfaces
Microridges help transport substances or provide stretch
What is the role of SSK?
adapted to withstand constant abrasion and desiccation
What are transitional cells?
Transition between stratified squamous and stratified columnar
What is the role of transitional cells?
Adapted to withstand stretch and toxicity
What are the two classification of glands?
Exocrine and endocrine
What is an exocrine gland?
Secretes the product onto a surface via the ducts
What is an endocrine gland?
Secrete product into the bloodstream
no ducts
How do glands develop?
Begin as secretory cells on surface of epithelium Unicellular glands and then multicellular glands form
Exocrine glands develop a duct with secretory cells at the bottom of a secretory unit
Endocrine glands- develop by the isolation of the bud of cells from the surface of the epithelium-isolated mass then acquires its own blood supply
What are the two types of exocrine gland classification based on their structure?
Ducts and secretory units
What types of exocrine duct glands are there?
Simple - unbranched
Compound-branched
What type of exocrine secretory unit glands are there?
Acinar- shaped like a hollow berry forms a spherical mass called an acinus with a central lumen extending to a duct
Tubular - test-tube shaped
What are the three different types of exocrine gland classification based on secretion?
Mucous glands
Serous glands
Seromuscus glands
Describe the mucous glands
Viscous fluid
rich in mucopolysaccharides to lubricate and protect
Describe the serous glands
watery fluid
rich in enzymes
Describe seromucus glands
contains both serous and muscous cells
Describe the serous cells
Cuboidal cells arranged around a central lumen with a sepherical nuclei
dark staining
Describe the mucous cells
Cuboidal cells arranged around a central lumen with flattened nuclei at base
pale staining
What is the method of discharge of merocrine gland?
Veasicle secrete contents into duct
What is the method of discharge of apocrine gland?
Secretory products are stored in the cell and pinched off portion of the cell in the secretion
What is the method of discharge of holocrine gland?
Cell shed into the duct and dying cell releases secretory products
replcacement cell will come along
What are the three adhesion specialisations of eptihelia?
Tight junction
Intermediate junction
Desmosone
What is a tight junction?
Membranes of adjacent cells are sealed together at points to prevent transport of substances between the cells
Maintains apical and lateral domains
What is an intermediate junction?
Ribbon- like adhering junction anchors to terminal web underlying apical membrane
What is a desmosone?
Spot like adhering junction- anchors to cell cytoskeleton
What are the 6 functions of the basement membrane of epithelia?
Anchors epitheilia and acts as a barrier
Defines cell polarity
Organise protein distribution in attached cells
Promotes cell survival, proliferation and differentiation
Serves as highways for cell migration
In tissue regeneration. can act as a scaffold for regenerating cells to adhere to
