Epithelial Cells Flashcards
(26 cards)
Define nuclear lamina
specialised cytoskeleton on internal surface of nuclear envelope, important in stabilising nuclear envelope in cell division
define peroxisome
single membrane that contains enzymes and is involved in lipid and aerobic metabolism oxidation reactions
What are microtubules made up of?
alpha and beta tubulin heterdimers that are 20nm thick
What are microtubules involves in?
cell shape, track for organelle movement and cytoplasmic components, major component of cilia and flagellae
What are intermediate filaments?
filament proteins that form rope like filaments 10-15nm in diameter
What are the types of intermediate filaments? Where are they found?
cytokeratins - epithelial
vimentin - mesenchymal
neirofilament - neurones
design - muscle
Whats is the function of intermediate filaments?
give mechanical strength and connects desmosome cell-cell adhesions
What are microfilaments?
polymers of actin that are associated with adhesion belts (in epithelial and endothelial cells) and other plasma membrane proteins, 5-9nm diameter
What are microfilaments involved in?
cell same and movement, accessory proteins act with actin to control movement and actin organisation
What are the types of microfilaments?
monomer = globular action = G-actin microfilament = filament action = F-actin
Name the cell types of give examples
connective tissue - fibroblasts, osteocytes, chondrocytes
contractile tissue - skeletal/cardiac/smooth muscle
haematopoietic - blood cells, bone marrow
neural - neurones, glial
epithelial
Define tissues
group of cells whose type, architecture and organisation are integral to function
What is an EC matrix?
tissue deposited by cells to form insoluble envorinement, that is composed of fibrillar proteins embedded in hydration gel
How are epithelial cells organised?
stable cell-cell junctions to form continuous cohesive layer
line internal/external surfaces
Where are cell-cell junctions found?
apical region of cell-cell contact as junctional complex
What are the 2 forms of cell-cell junctions
zonulae/belts
maculae/spots
How are cell-cell junctions typically arranged?
an apical junctional complex contains tight junction near apex, then adhesion belt, then desmosomes/spot adhering junctions throughout lateral membrane
What is the arrangement of a tight/belt junction?
points on adjacent membranes form close contacts at apical lateral membrane, highly elaborate networks contacts create tight seal for paracellular pathways
Function of tight/belt junction?
segregates atypical and basolateral membrane polarity
What is the arrangement of an adhesion belt?
formes basal to the apical tight junction, adhesion molecule is cadherin which associates with microfilament cytoskeleton
Function of adhesion belt?
controls assembly of the other junctions
What is the arrangement of the the spot junction/desmosomes?
found at multiple spots between adjacent cell membranes with a cadherin-Like adhesion molecule
linked to intermediate filament
Function of spot junction
provides mechanical continuity between cells
What is the arrangement of a gap junction?
clusters of pores that are continuous with pores in adjacent cell membrane
