Need to link cytoskeleton to adjacent cells to each otherOr, need to link cyto skeleton to the extracellular matrix.
- The Ziploc bags of the tissue world
- Form a tight leak proof seal between two or more cells where substances cannot be allow to percolate between cells
- Example: in the inestines where it is important to keep the outside out (in the intestinal lumaen) and keep the insides of the intestinal cells from getting stale and moldy.
What are the different types of Cell Juncitons?
- Tight junctions
- Adherens junctions
- Gap junction
- These use a protein called cadherin
- These work like a belt on your pants, keeps tissues from separating as they stretch and contract
- are used as "spot welds" to hold tissue together against mechanical disruption.
- These junctions are cadherin between the cells, with intermediate filament proteins in each cell to form a continuous, strong, structure.
- Half of a desmosome
- found between a cell and its basement membrane
- On the cell side, intermediate filaments anchor the cytoskeleton to the integrins, which are in turn connected to the basement membrane.
- The other junctions serve as mainly mechanical links
- In contrast, the gap junction serves as an electrical and biochemical link between two cells.
- A protein, connexin, forms pore-like structures called connexons (these allow small ions to pass from cell to cell)
- Monomers and polymers can pass between cells as well.
- If a cell becomes very sick, these connexons can seal off like a ships hatch, isolating the damaged cell so that it can die alone without making others sick.
What are Membranes?
- Flat and flexible sheets which form a lining where parts of the body come together
- They consist of and epithelium plus underlying areolar connective tissue.
Epithelial Membranes= epithelium + connective tissue
- -Mucous membranes
- -Serous membranes
- -Cutaneous membranes
Graphic objective 21. Describe the five main types of junctions between cells. Name the most common locations or tissue types where each type of junction is found.
Graphic objective 22. Define, and name key features of, the different types of epithelial membrane: mucous, serous, and cutaneous