lecture 10 - regeneration Flashcards
why do we age?
genomic instability, telomeres attrition, epigenetic alterations, stem cell exhaustion
what are the 3 types a tissue can grow?
1) Regulation of cell number via the Hippo pathway
- activated by growth factors; it is a mechanosensing pathway and its inactive if there is mechanical stress acting on the cell
- activity of Yap1 promoter: the Yap1 signaling controls size of liver post development
2) Regulation of cell size
- TOR = target of rapamycin which is an anticancer drug
- stimulates cell growth and metabolism
3) Growth by accretion
- how bones grow: cells are excreting stuff increasing the size of the ECM
what are the 2 types of regeneration?
1) EPIMORPHOSIS - extensive cell proliferation of somatic stem cells; blastema formation; dedifferentiation of cells
2) MORPHALLAXIS - regeneration by transformation of existing body tissues (only reorganization of existing body cells - NO blastema formation)
why was regeneration lost?
regeneration was lost due to arising of complexity of organisms;
it became metabolically expensive, highly energy costly; conservation of ageing is cheaper to maintain the body
regeneration is not the same as repair and simple wound healing is not as costly so that is why organisms switched to repair
