Lecture 5 Flashcards
(21 cards)
What is the Basal lamina?
Also known as the basal membrane, it is a 2d membrane that usually underlies the epithelial layers, it can also surround muscle fibres or in the glomerulus in the kidney
What are the components found in the basal lamina?
Collagen IV, Laminin, nindogen and perlecan
What is the fibrillar matrix?
A 3d structure that is more loosely organised compared to the basal lamina, mesenchymal cells are embedded here
What are mesenchymal cells?
AKA fibroblasts, they from projections and touch the fibrillar matrix
What components are found in the fibrillar matrix?
Fibronectin, elastin, collagen I and proteoglycans (proteins with a sugar side chain)
What is the basal surface?
The surface that faces the basal membrane/lamina
What is the apical surface?
Opposite of the basal surface, in epithelia it is where nutrients come in and where digestion takes place
What are the anchoring junctions?
Adherens junctions, desmosomes, hemidesmosomes, focal adhesion
What are desmosomes?
Anchoring junctions between two cells that attach intermediate filaments
Formed by cadherins
What are hemidesmosomes?
Found between the basal surface and basal lamina and attach a cell to the basal lamina
Attach to the intermediate filaments
What are tight junctions?
They are found between cells
Bring the cell membranes close together to prevent passage of molecules between them
Formed from claudin and occludin
Prevent the loss of water and transport of random molecules
What are gap junctions?
Found below TJ
Allow the passage of molecules between cells up to a weight of 1KD
Channels that can be closed or opened due to many factors
What are adherens junctions?
Like desmosomes but they attach to actin filaments instead of intermediate filaments
What do actin and myosin do in the epithelia?
Mediate contractile forces to lead to bending of the epithelia
What are focal adhesions?
They link actin cytoskeleton to the extracellular matrix
They form and detach to allow actin stress fibres to reach out to surfaces and detach from them to move
What are cadherins?
Homophilic adhesion molecules that attach cells to each other
They are calcium ion dependent
Structurally, they are transmembrane proteins
Where are cadherins found?
Desmosomes and adherens junctions
Where are E cadherins found?
Epithelia
Where are N cadherins found?
Neurones, heart, skeletal muscle, lens, fibroblasts
Where are P cadherins found?
Placenta, epidermis, breast epithelium
Where are VE cadherins found?
Vascular endothelial
