Tissues, Organs And Systems Flashcards
What is the role of tight junctions?
Prevent movement of larger molecules through the lumen
In the gut can transiently open to allow small molecule to cross to the underlying tissues (paracellular transport)
What is the role of adhesion junctions?
Tissue stabilising factor and additional transport barrier
Only found in epithelial and endothelial cells
Found in lateral surface 1/3rd distance from luminal surface
What is the role of desmosomes?
Strongest of all cell-to-cell adhesions
1/2 way between top and bottom of cells
Tissues that experience intense mechanical stress- provides mechanical strength and prevents tissue destruction
What is the only cell-to-cell adhesion found in the upper epidermal cells?
Desmosomes
What is the role of gap junctions?
Quickly communicate changes in intercellular molecular composition eg. Electrolyte and energy changes
Allows free movement of small molecules from one cell to another
What are cell adhesion molecules?
A collection of proteins on the cell surface that are necessary for the process by which cells adhere to the extracellular matrix, one another and their surroundings
What is a hemi-desmosome?
Only found on basal surface of epithelial cells
Attach to a layer of extracellular matrix
Anchors epithelial cells to the basal lamina
What are focal adhesions?
Anchor epithelial cells to the extracellular matrix
Uses intracellular actin filaments
Uses integrins
Binds to fibronectin
What are integrins?
Central to cohesive forces holding tissues together
Work as an alpha beta-dimer (weak)
Phosphorylation produces heterotetramer (strong)
What are proteoglycans?
Support hydration of extracellular matrix of normal skin
Supportive scaffolding roles
Controls bioavailability of growth factors in the ECM- stimulate cell populations in skin that orchestrate the normal turnover and repair