Stem cells Flashcards
what are stem cells?
unspecialized cells that can reproduce themselves and generate more specialized cells indefinitely
two types of stem cells
Embryonic stem cells: pluripotent (can differentiate into any linage of cells)
Adult stem cells: multipotent (can differentiate into some cell types)
Cell fates are progressively restricted during development
what tissues are set-renewing?
epithelial tissues connective tissues skeletal muscle endothelial cells blood cells
What is epithelial tissue and where are stem cells found in them?
lining of small intestines. stem cells are near the base of crypts where dividing cells are confined, as they move to the top of villi they are differentiated and do not divide.
what are the types of cell made in epithelial tissues? which one is special?
Paneth cells: sit at the bottom of crypts but do not divide
absorptive cell
goblet cell
enteroendocrine cell
what is Wnt?
Wnt signaling maintains epithelial cells in proliferative state. as cells leave the crypt, they have less Wnt exposure and stop dividing
what are connective tissues? how are they differentiated?
these cells synthesize various types of ECM, support other tissues, and play a role in repair. differentiation can depend on properties of the ECM, like still ECM makes bone cells while soft ECM makes fat cell
what are osteoblasts and osteoclasts?
osteoblasts: secretes bone matrix for remodeling
osteoclasts: remove old bone matrix
when bone remodeling is unbalanced what diseases occur?
Osteoporosis: too much removal
Osteopetrosis: too much secreted
why are satellite cells necessary in muscle fibers?
once differentiated into skeletal muscle fibers, cells do not divide or replicate DNA. In order for the tissue to heal, satellite stem cells lie inactive near the mature muscle cell and can activate to proliferate and fuse progeny with damaged muscle.
what are endothelial cells? How do they contribute to remodeling?
cells that line the blood and lymphatic vascular system, controlling passage of materials in/out bloodstream. the vascular system is continually remodeled and endothelial cells can be used to form capillary sprouts
what signals are involved in triggering endothelial cells to move blood?
vascular endothelial growth factor: secreted by tissues that require blood supply. both a growth and survival factor
HIF1alpha: stimulates transcription of VEGF proteins when short on oxygen
Red blood cells vs platelets?
red blood cells: found in blood vessels and transport O2 and CO2. Cannot grow/divide. Erythropoietin is secreted when lacking oxygen necessary for survival
platelets: mini cells used to help with repairs and clotting
Three classes of white blood cells
granulocytes: little guys
monocytes: precursors to macrophages
lymphocytes: B or T cells
how do stem cells stay stem cells? when do they start to differentiate?
stem cells require signals. there is a region where they must stay to remain stem cells because that’s where signals are. if it leaves that region it will differentiate
