Week 4 Flashcards
Top 5 cancers
skin, breast, colon, lung, prostate
all carcinomas
Life and death of
keratinocytes in epidermis
Approx. two weeks to
mature, subsequently die
and detach
Epithelium folding increases
surface available for absorption
compared to unfolded epithelium
villus/villi
tiny, finger-like projections made up of cells that line the entire length of your small intestine
inside villus “finger”
connective tissue
Between villi, the epithelium folds
down into connective tissue,
protecting stem cells at the base of
these “crypts” .
basal lamina
/ basal layer / basement membrane
separates underlying connective tissue (dermis) from keratinocytes in epidermis
in order to invade dermis, cancer cells must cross…
the basal lamina
“in situ”
in place
Common cells of the epidermis:
Melanocytes
Keratinocytes
Langerhans cells
Merkel cells
Langerhans cells
of neural cell
origin in bone marrow; immune
system cells
Merkel cells
are sensory
cells detecting pressure
melanocytes
A cell in the skin and eyes that produces and contains the pigment called melanin
moved into epidermis
during embryo development
Dermis
cell density is low, cells embedded in extracellular matrix (ECM)
secreted by fibroblasts or related cells (e.g., osteoblast cells in bone)
fibroblasts
most common cell type in connective tissue
produce collagen
are motile - crawl within the extracellular matrix
secrete the proteins and sugars of extracellular
matrix such as collagen.
also function like stem cells or embryo cells
divide and daughter cells may differentiate into
different cell types such as lipocytes or adipocytes (fat cells,)
and osteoblasts (bone cells)
most human cells diameter are about
10-30 μm
lipocytes or adipocytes
fat cells
osteoblasts
bone cells
Non motile melanocytes that can divide and produce
motile melanoma cells
also Motile fibroblasts that can divide and produce non motile
fat cells
have same genes - but different structure and function due to changes in gene expression and mutated genes producing new alleles
life of keratinocytes in epidermis
two weeks to
mature, subsequently die and
detach
normal stem cells
divide only if
chemical signals are present
Cancer stem cells divide in an
unregulated way without chemical signals required
stem cells
undifferentiated, unspecialized
TACs
transit amplifying cells
committed cells
committed to a certain fate - differentiating
post-mitotic differentiated cells
A mature, terminally differentiated (TD) cell no longer able to undergo mitosis
TACs contribute most to cell
number and replacement in…
epithelia
multipotency
the ability to differentiate into multiple cell types, but only a limited number of closely related lineages
progenitor
ancestor
progeny
offspring
unipotent
division and differentiation produces one thing
- basal stem cells … only produce keratinocytes
In basal cell cancer (BCC) cells look
less
differentiated, like basal stem cells
In squamous cell cancer (SCC),cells looks
more differentiated like squamous cells.
Most online content still states that BCC
comes from mutant stem cells and SCC
comes from mutant squamous cells (TACs) but…..
More recent research indicates that both BCC and SCC originate in basal cells
most common skin cancer USA
Basal Cell Carcinoma
~1.3 mil
most rare skin cancer USA
melanoma, but it is the most
(even though epidermis has more TACs than basal cells)
aggressive
avg skin cancer deaths a year usa
~10,000
permanent cells
(lasts lifetime)
These cells are abundant in nervous system,
muscles and the lenses of the eyes; they are
non-dividing – cancers rarely or never occur
Shorter lifespan cells
typically live for days,
weeks or months, as in blood, colon,
epidermis and lungs; mutant stem cells are
more likely to result in tumours due to cell
division
neovascularization
the process by which new vascular structures assemble.
