exam practice answers -...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
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
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
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 
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 6

exam practice answers -...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online