Tight Juctions, Gap Junctions and Animal Extracellular Matrix

1. Tight Juctions, Gap Junctions and Animal Extracellular Matrix By: Christina Szabados

2. Tight Junctions Occur when the membranes of two cells move close to each other in order to prevent molecules from passing between cells. This helps in holding cells together.

3. Fence Function This function ensures that molecules in the apical outer membrane will not mix with the those in the lateral membrane of the cell, by blocking the movement of proteins in the membranes.

4. Barrier Function • Does not allow the passage of molecules from one cell to another. • This forces material to go through the cell, so the transportation of materials is regulated within the cell. • Molecules regulated can include ions, water, macromolecules, and cancer cells.

5. Tight Junctions Also… • are prevalent in the cells in the skin, gastrointestinal track, respiration, actin, cytoplasm, and ATP • are responsible for the blood brain barrier, which protests the nervous system. • make and maintain the cell polarity of the cell, by regulating the structure of the cell’s lining during polarization.

6. Diseases From Tight Junction Malfunctions • Disorders in tight junctions can cause jaundice, diarrhea, and edema • In order to regulate molecules passing through the cell, tight junctions force molecules such as cancer cells to pass through a cell. If there is a problem in this process cancer can occur.

7. Gap Junctions • Are a passageways between two cell membranes, that connect the cytoplams of the cells. • They are formed by which come together in neighboring cells to form passageways between them. • The opening and closing of connexins can be controlled within the cell Connexins,

8. Gap Junctions can be found in the cardiac muscle of the heart, neurons in the brain, and neurons in the retina. They also insure the molecules passing between cells do not leak into the intercellular space.

9. Diseases from Gap Junctions Those who are predisposed to having an arrhythmia and have a heart attack often have a defect in the gap junctions of their heart. This defect can be an alteration in the gap junction or a problem with the connexins.

10. The EMC is connective tissue made from proteins and polysaccharides. This tissue has elastin fibers to create elasticity in cells, so structures such as the lungs can be both flexible and strong. Animal Extracelular Matrix

11. Functions: -Gives animal cells diverse structural support such as in the bones, cartilage, and the eye’s cornea. The differences in necessary functions requires a diversity of forms in the EMC which is achieved through different amounts of macromolecules in the tissue. -segregates tissue -regulates the communication within cells -aides in growth, wound healing, and fibrosis

12. Extracellular Matrix Diseases • Cells are extremely dependent on the EMC for survival. • Cellular diseases can result from the build up of toxins in the extracellular matrix, therefore it is prevalent in areas which are heavily polluted. • The abnormal transformation of cancer cells, because they often lack fibronectin in the EMC, causes less adhesion, this can result in the cancer cell breaking off from the tumor and spreading to other parts of the body.

13. Sources: www.wentweb.com/images/brain_001.jpg www.biologyreference.com/Ce-Co/Cell-Junctions.ht kwjersey.com/wp-content/uploads/take-down-fence resources.metapress.com/pdf-preview.axd?code=bl www.springerlink.com/content/blvd0k5ptlvbtwlt/ en.wikipedia.org/wiki/Tight_junction /cardiovascres.oxfordjournals.org/cgi/content/ab circres.ahajournals.org/cgi/content/full/86/12/1 en.wikipedia.org/wiki/Gap_junction www.integrativedentalmedicine.com/TABS/ecm.jpg www.offthemarkcartoons.com/cartoons/1996-03-29.gif academic.brooklyn.cuny.edu/