Moss - Tissues and Stem Cells Flashcards
what happened to cells due to the evolution of multicellularity?
cells in the human body have lost the capacity for independent survival, rather they are members of a cohesive and integrated organism
how many cells are there in the human body?
more than 1014
how many distinct varieties of cells are there in the adult human body?
~210, not including subtle differences
what do all cell varieties have?
the same genome
how can similar-looking undifferentiated cells give rise to very different adult organisms?
through development
what cells divide and differentiate into mature cells found in tissues and organs?
stem cells and progenitor cells
what are the three main factors that contribute to the stability of tissue organization?
cell-to-cell communication
selective cell adhesion
molecular cell memory
what contribution does cell-to-cell communication give to the stability of tissue organization?
direct contact and diffusible signals will influence the survival, proliferation, and behavior of cells
what is an example of cell-to-cell communication in tissue stability/organization
tissue growth can induce the formation of blood vessels; nerves die if they don’t find a cell to innervate
what contribution does selective cell adhesion give to the stability of tissue organization?
cells form selective attachment to other cells or to the basement membrane or ECM
loss of attachments can change their cell behavior
what kind of binding do cadherins and other cell adhesion molecules use?
cadherins and other cell adhesion molecules follow certain molecular rules, such as homophilic binding
what contribution does molecular cell memory give to the stability of tissue organization?
gene expression patterns established during development are stabilized, thus maintaining cell identity throughout life
even as cells proliferate and generate new cells, they pass on the inherited pattern to their cellular progeny
in what way would skin be classified?
as a stratified squamous epithelium
what happens to cells in the epithelium?
the basal cell layer is attached to the basal lamina
as cells begin to die they detach from the basal lamina, move up through the different layers until it reaches the surface and flakes off
what are the different layers found in the epithelium (from top to bottom)?
Squame about to flake off
keratinized squames
granular cell layer
prickle cell layer
basal cell layer
basal lamina
connective tissue of dermis
what skin layers are keratinocytes?
basal cell layer
prickle cell layers
granular cell layer
keratinized squames
how would the cell layers in the intestine be classified?
simple columnar epithelium
TRUE or FALSE: Progenitor cells have limited capacity to divide
TRUE
TRUE or FALSE: Stem cells have a lifetime capacity to divide as long as they are in the stem cell niche
TRUE
In the lumen of the gut, how do cells develop?
cells move up from the bottom as they develop from dividing stem cells
once stem cells divide, they become dividing precursor cells
once they reach the top of the crypt, they become nondividing terminally differentiated cells
in the case of the gut lumen, absorptive cells and secretory cells
what do all self-renewing tissues have?
stem cells
what are stem cells?
multi- or pluripotent (maybe totipotent)
practically unlimited division potential
daughters either remain stem cells or become committed to differentiation
what is multipotent?
many cell types
what is pluripotent?
all cell types of the body
what is totipotent?
all cell types, plus extraembryonic tissues
what are the three ways stem cells may divide?
symmetrically
asymmetrically
symmetrically with commitment
why are stem cell divisions slow?
to preserve the genome
what is symmetric division of stem cells without commitment?
stem cells divide and their daughters remain stem cells