Tissues & Stem Cells Flashcards
How many cells in the human body & how many differentiated cell types are there?
What are the 4 basic tissue types?
What is the human cell atlas? What does a dot & cluster on the map show?
What are the techniques used for this?
30 tril- 250
connective, epithelia, muscular, nervous
Map of all cells in human body for health, diagnosing & treating disease. Dot = cell, cluster = gene expression, clusters further away = more distinct gene expression
Single cell RNA seq, mass cytometry, epigenome seq, in situ analysis
What is the definition of a tissue?
How many types of connective tissue are there and where is it derived from?
What is loose tissue & what is its function?
What is dense tissue?
What is cartilage tissue & where is it found?
How is bone formed? What is its function?
What is adipose tissue for? What are the cells involved?
What is blood?
Set of cell types from a single-type stem cell that work together to carry out a specific function
5-6- mesoderm & some from neural crest
Loose: fibroblasts in loose fibres (collagen/elastin/reticulin)
Surrounds blood vessels, nerves. Connects tissues & organs, supports epithelia
- vertebrates
Dense: fibroblasts embedded in dense collagen fibres - forms strong ropes = tendons & ligaments
Chondrocytes embedded in matrix (collagen/elastin/proteoglycans) & supports tubes & tissues against friction
Chondrocytes secrete chemicals in cartilage to signal replacing with bone in ossification- formed from mesoderm & neural crest. Embedded in collagen matrix
Skeleton- protects internal organ & attachment points for muscles
Storing fat- adipocytes
Blood cells suspended in plasma- also granulocytes, monocytes, platelets, lymphocytes
What are epithelial tissues?
What are their functions?
What are the 3 junctions that tightly join epithelial cells together?
What is apical-basal polarity?
How is the cell joined to the basement membrane?
Sheets of cells that cover surfaces & line tubes (digestive tract)
Separating inside from outside (lining/protecting insides of organs)
Tight: near apical surface & provide semi permeable barrier- found in vertebrates
adherens: made of cadherins which link to actin cytoskeletin via catenins- between tight & desmosome
desmosome: strong cell-cell adhesion junctions that attach to intermediate filaments
Basal surface joined to basement membrane & apical surface faces a lumen & contains microvilli & cilia
Hemi-desmosomes: like desmosome but link to basement membrane
What is the difference between simple & stratified cells?
What is the difference between cuboidal, columnar & squarmous cells?
What do pseudostratified cells look like?
Simple = 1 layer of cells in sheet of tissue Stratified = many layers cells in sheet of tissue
Cuboidal = circles/squares Columnar = rectangular Squamous = flattened
Look stratified but their cells contact apical & basal surfaces
What are the 3 types of muscle tissue and what do they look like/composed of?
Skeletal = multinucleate myofibres with contractile proteins actin 7 myosin arranged in repeating patterns of sarcomeres (creates striations)
Cardiac = striated too but is made up of individual cells that are mono/binucleate joined by intercalated discs with gap junctions for rapid spread signals
Smooth = bundles of spindle shaped mononuclear cells & have similar contractile function to skeletal but not arranged in sarcomeres
What is the neural tissue composed of?
What are the different subtypes of neurones?
What are the different types of support cells in the CNS & PNS?
What are neurones grouped into?
Neurones & support cells (neuroglia)
Motor = synapse to muscles Sensory = receive from stimulus Inter = carry info between both
Neuroglia:
CNS = Astrocytes (synapses), oligodendrocytes (mylenate), microglia, ependymal cells
PNS = Schwann cells (mylenate), satellite cells
Ganglia & peripheral nerve (fibres)
What is the definition of an organ?
What experiment/event showed the rapid turning over of intestine cells?
Collection tissues combine to carry out a specific physiological function
Carbon-14:carbon-12 ratios- people born between 1950s-1960s had high concentration of C-14 in cells & the more C-12 in their tissues over time showed the rapid turnover of cells- particularly in intestine (brain is less rapid)
What is the definition of an organ?
What experiment/event showed the rapid turning over of intestine cells?
What is occurring in the crypts of intestines?
Why do the intestinal cells need to be constantly renewed?
How often do these cells replace & what cells are they?
What are the 4 capabilities of stem cells?
Collection tissues combine to carry out a specific physiological function
Carbon-14:carbon-12 ratios- people born between 1950s-1960s had high concentration of C-14 in cells & the more C-12 in their tissues over time showed the rapid turnover of cells- particularly in intestine (brain is less rapid)
Rapid proliferation of intestinal cells
To maintain the permeable barrier
6-7 days, stem cells
Undifferentiated, unlimited proliferation, self renewal, differentiation
What type of division is self renewal?
Differentiation?
Self renewal & differentiation?
What is often the intermediate step?
Symmetric- 1 stem cell into 2 stem cells (identical daughter cells)
symmetric- 1 stem cell into 2 transit amplifying cells
1 stem cell into 1 stem cell & 1 transit amplifying cell = asymmetric
Transit amplifying cells proliferate to get several rounds of division to differentiate many daughters
Where do stem cells reside? What are they necessary for?
What are germline stem cells ‘controlled’ by?
What happens if these stem cells are not in contact with the cap cells?
Niche (signalling centre) determine the type of division symmetric/asymmetric
In contact with somatic cap cells which secret Dpp (BMP-like signalling protein)= self renewal signal (asymmetrically or symmetrically)
Undergo differentiation (no self renewal just transit amplifying cells)
What are the 3 types of potent stem cells?
What are the 4 main types of stem cells?
Pluripotent: differentiate into cell types from all 3 germ layers
Multi-potent: differentiate into closely related cell types e.g from 1 germ layer
Unipotent: differentiate into 1 cell type
Embryonic stem cells = pluripotent
Adult/tissue stem cells = multi/unipotent
Neural stem cells = multi/unipotent (more differentiated)
Induced pluripotent stem cells = generate in vitro due to forced reprogramming (pluri)
What type of stem cells reside in the crypts of the intestine?
How can you visualise the stem cells & their renewal & differentiation?
What niche do these stem cells reside in? What do they signal?
What are the 3 zones in the crypt?
What is the path that the differentiated cells take out of the crypt?
What are the 3 types of differentiated cells in the villi & what are their functions?
How often is the epithelial lining replaced?
Adult tissue (multipotent)
Genetically label them- form streams up to the tip of villi of labelled stem cells & descendants
Paneth cells: secrete Wnt signalling promote self renewal
Rapid division, transit amplifying zone, differentiation
Along villi, differentiate along the way & undergo apoptosis at tip of villi & shed into intestinal lumen
Enterocytes: absorb materials from gut
Goblet cells & enteroendocrine cells: secrete material into lumen
5-7 days
Lateral inhibition in the intestine:
What contact is required in notch signalling?
What happens in high notch signalling?
Low notch signalling?
What does Math1 do?
What is Delta & what does it do?
So what happens to the adjacent cells if one cell has low notch signalling?
How is intestine stem cell competition demonstrated?
Cell-cell contact signal (ligand (delta)-receptor (notch))
Down regulated Math1 (TF) = absorptive progenitor to form enterocyte
High regulated Math1 = secretory progenitor = secretory cells such as enteroendocrine, goblet, tuft, Paneth
TF that activated Delta to promote development of secretory progenitors
Notch ligand- activates Notch in the adjacent cells to inhibit neighbours from becoming absorptive
Math1 is highly regulated in that cell so it becomes secretory progenitor- but the high regulation of Math1 means high regulation of Delta which activates Notch in the adjacent cells- so high notch signalling in adjacent cells means they become absorptive progenitor
In chimeric mice with different fluorescently labelled stem cells markers- crypts later become single coloured rather than multicoloured due to symmetric division taking over of 1 specific stem cell type
Haematopoietic stem cells are another tissue stem cell- what is their potency and what can they differentiate into?
How can these be used for bone marrow transplant? What are the steps involved
Multipotent- 2 pathways
1- lymphoid stem cell (B & T cells)
2- myeloid lineage
- Remove healthy bone marrow & collect the stem cells
- Freeze & store the stem cells
- Chemotherapy to destroy bone marrow
- Return stem cells to blood stream
Haematopoietic stem cells are another tissue stem cell- what is their potency and what can they differentiate into?
How can these be used for bone marrow transplant? What are the steps involved
Multipotent- 2 pathways
1- lymphoid stem cell (B & T cells)
2- myeloid lineage
- Remove healthy bone marrow & collect the stem cells
- Freeze & store the stem cells
- Chemotherapy to destroy bone marrow
- Return stem cells to blood stream
