exam practice answers - o o o Metastasis:spreadof

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Tumorigenesis stem form errors in signallign pathways and cell cycle regulation mehcanisms Cancer—cell proliferation exceed cell death or at equilibrium o Uncontrolled cell growth—lose equilibrium o Unresponsive to reugaltion o Caused by mutaitons in somatic cells Metastasis: spread of utmor cells, enter circulatory system o Proliferate and establish secondary area of tumor growth o Loss cellspeicfic markers Benign tumor Malignant tumor Slow growth, localized Closely resemble normal cells Express normal cell specific markers Does not metastasize Mass effect Divide rapidly High nucleus/cytoplasm ratio Less differentiated than normal cells Loss of cell specific markers Invades surrounding tissues (metastasis) 5 main classes of tissues in vertebrates o Epithelial o Connective o Muscular o Nervous o Blood  4 major families of CAM o Caderins o IG superfamily o Integrins o Selectins 3 major classes of cell juncitons o Anchoring junctions CAM-cadherins Other components- adaptor proteins Role-connect adjacent cells, connect cell to ECM o Tight juncitons CAM- Other components- Occludin, Claudin-1, JAM Role-establish and maintain cell polarity, barrier that seals off one side of layer form other o GAP juntions CAM-  Other components-connexions  Role-gap jucniton channel to  move ions, secondary messengers  Steps of extravasation (CAM, upregulated CAM,  ligands of CAM, receptor ligand how facilitate  movement through endothelium) Extravasation 5 step process 1. Capture o Inflamed tissue released cytokines –  activate endothelial cells o E.g. TNF alpha stimulates the endothelial cells to reveal the surface  adhesion molecules, p-selectin and E-selectin 2. Rolling adhesion
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o  P-selectin and E-selectin interacts with carbohydrate groups on the surface of leukocytes o Selectin ligand: e.g. sialyl Lewis x (SLEX) like glycans are expressed in relatively high numbers by  circulating leukocytes 3. Slow rolling o Increase in Selectin expression further slows movement o molecules   4. Tight binding or firm adhesion—mediated by integrins o Platelet activating factor (PAF) on epithelial surface signals leukocyte to activate integrins o Activated integrins can bind intercellular adhesion molecules (ICAM) on surface of epithelial cell  firm  adhesion  arrests cell movement 5. Transmigration Cyclin Made  Function  Inhibition mid G1 At end of  mitosis  Induce synthesis of proteins required for DNA synthesis –  phosphorylates and activates transcription factors that control expression  of S phase protein Mitogen induces its 
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exam practice answers - o o o Metastasis:spreadof

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