Epithelia Tissue Flashcards
(24 cards)
What is the function, locality and proteins involved with adheren cell junctions?
Function = “Belt desmosome” appearance. Plaque layer of proteins on inside of cell to join actin to cadherins. Prevent cell seperation from forces.
Locality = places where organs contract ie heart or muscles
Proteins = Cadherins link to actin via catenins
What is the function, locality and proteins involved with tight cell junctions?
Function = Restrict flow of substances through plasma membrane between cells.
Locality = stomach, intestines &urinary bladder
Proteins = claudins and occludins. ZO-1 joins cytoskeleton of cells to actin
What is the function, locality and proteins involved with desmosome cell junctions?
Function = Resist shearing forces and have a plaque
Locality = muscles, lateral wall, skin epithelium and cardiac cells of the heart
Protein = Cadherins span the gap, BUT link cell surface to keratin. Keratin spans from one desmosome to another on the other side of a cell.
What is the function, locality and proteins involved with gap cell junctions?
Function = transfer of small molecules from cell to cell
Locality =
Protein = connexIN
6 connexIN = 1 connexON/hemichannel
2 hemichannels make up 1 gap junction
What is the function, locality and proteins involved with hemidesmosome cell junctions?
Function =. Connect EPT to BM. Links cellular basal intermediate filament keratin to BM.
Locality = basal surface
Protein = Intergrin linker protein binds to laminin in BM and to keratin
What forms a junctional complex?
tight junction, adherens junction and desmosome
What are the 2 parts the BM is composed of? And what are those components made up of?
Reticular lamina and Basal lamina
Reticular lamina = produced by fibroblasts in CT and made up of fibrous proteins fibronectin collagen etc
Basal lamina = secreted by EPT, contains collagen, laminin, proteoglycans, glycoproteins etc
What is the function of the BM?
Support
provide a surface for migration during wound healing.
physical barrier
participates in the filtration of subs in the kidney
How does EPT receive nutrients and get rid of waste?
EPT is avascular, therefore receives nutrients from the CT via diffusion
Explain how the BM acts as a barrier for malignant melanoma? What does ABCD stand for?
Once the BM has been penetrated, the chance of metastasis increases.
Concept of ABCD A asymmetrical B border irregularity C colour D diametre
What are the 2 types of EPT?
- Covering and lining - outer lining of skin and some organs, inner lining of BV, ducts and body cavaties, respiratory. digestive, urinary and reproductive systems
- Glandular (exocrine and endocrine) - constitute the secretory portion of glands
Explain simple, stratified and pseuodstratified epithelia in terms of arrangement and function
Simple = singler layer of cells. secretion; absorption; filtration
stratified = two or more layers. protective
pseudostratified = “fake” appears to have many layers but only has one due to all nuclei touching BM. not all cells reach the apical surface. Actually a simple E therefore role is secretion.
Which shape allows for diffusion?
Squamous - flat and thin
which shape is more tall than wide? and what is its function?
Columnar = increase S.A for capacity to absorb and secrete substances
which SHAPE of epithelia cells are found in the urinary bladder and why?
Transitional - because at a relaxed state the shape is cuboidal and stretches to flat once the bladder is full.
What are the roles of Mesothelium and Endothelium?
Mesothelium = lines pericardial, pleural, peritoneal cavaties
Endothelium = lines inside of heart, blood and lymphatic vessels.
what is a location of simple squamous epithelium?
Bowmans capsule of kidney cardiovascular and lymphatic systems alveoli of lungs visceral cavity linings inside heart and BV
What are the locations of simple cuboidal epithelium?
Hint* their role is secretion and absorption
pancreas ducts, parts of kidney tubules, smaller ducts of many glands, secretory chambers of thyroid, anterior surface of lens, pigmentated epithelium at posterior of retina, secretory part of some glands like thyroid
Explain the features/appearance and subtypes of simple columnar epithelium
Features = elongated (nucleus also) therefore more organelles
subtypes = cilia (movement) or microvili (increase S.A or “brush border”)
A modified columnar cell (non-ciliated) can contain what?
Goblet cells which secret mucous
Where can ciliated simple columnar epithelium be located?
Fallopian tubes, bronchioles, sinuses, central canal of spinal cord, ventricles of brain
Where can the subtypes keratinised and non-keratinised occur in EPT?
Stratified squamous epithelium (where stress often occurs)
Keratinised = skin non-keratinised = mouth, throat, tongue, oesophagus, anus, and vagina
where do endocrine glands secrete onto? And give an example
directly into the blood via traversing interstitial fluid
Pituitary, pineal, thyroid, parathyroid
distant strong effects
where do exocrine glands secrete onto? And give an example
into ducts that empty onto the surface of covering or lining epithelium
sweat and salivary glands; oil glands; wax glands; pancreas
local effects
