M2 L7 Flashcards
(21 cards)
features of stem cells
- can renew and regenerate for a long time
- undifferentiated
- able to produce differentiated cells
what are the 2 main types of stem cells?
pluripotent
- eg. embryonic stem stem cells
- can become any cell type (almost)
multipotent
- eg. adult stem cells
- stem cells within specific organs can become the major cell types within those organs
what are induced pluripotent stem cells?
stem cells that are induced to pluripotency by the expression of 4 genes
can be used for transplants that don’t reject
what happens when cells die
they have to be replaced in
- correct types
- correct amounts
- correct places
stem cells in epidermis repair
- found under sebaceous gland in bulge
- can translocate to the basal layer
- different stem cells responsible for hair growth
- turnover ~ 2 months
stem cells in digestive repair
-turnover is few days
- found in deep crypts
- can become: goblet cells, paneth cells, absorptive cells, enteroendocrine cells
what are the two main types of environmental change and the broad response
- physiological and pathological
- homeostatic mechanisms
what is the general responses to tolerable change? + eg of tolerable environment changes
- cell size change
- cell division
- cell differentiation
- puberty, lactation etc
what is hypertrophy/ hyperplasia?
- increase in cell size/proliferation rate
- reversible by atrophy/involution
what are two examples of hyperplasia/hypertrophy?
-breast engorgement in pregnancy
- endometrial growth due to ovarian tumour
what is metaplasia?
- one fully mature cell type reversibly changes to a different fully mature cell type
- can be adaptive
- common in epithelia
what are 3 examples of epi metaplasia?
cigarette smoke in bronchus
- cilliated pseudostrat columnar -> strat squamous
bladder stones in urethra
- transitional -> strat squamous
barrett’s oesophagus (gastric acid in oesophagus
- stratified squamous -> columnar with microvilli and goblet cells
what happens if cells can not adapt to the environment change?
- cell injury/death
OR - stimulus: mild sublethal DNA damaging
-> dysplasia
-> neoplasia
what is dysplasia
- presence of abnormal cells
- increased rate of cell division
- incomplete maturation
- ceases at stimulus removal
what is neoplasia?
- uncontrolled cell division causing mass formation
- proliferation and growth in absence of external stimulus
- failure of cell growth control mechanisms
- varying states of differentiation, often failing to fully differentiate
- changes to genes are passed down to progeny
what are two examples of dysplasia in epi
sunburnt skin
- nuclei still present in keratin layer
cervix
- increased number of more basal/ nucleated cells reaching the vagina
- spectrum of loss of differentiation
- can become neoplastic
what is malignant?
- can lack differentiation
- erratic growth
- locally invasive
- metastatic
what are the four classifications of epithelial tumours?
covering epithelium
- malignant: carcinoma
- benign: papilloma
glandular epithelium
- malignant: adenocarcinoma
- benign: adenoma
what occurs during metastasis
- detachment from main neoplasm
- break through basement membrane and connective tissue
- get into transport source
- enter new tissue type
what are the four metastatic routes
- local
- bloodborne
- lymphatic
- transcoelemic
-> pleural
-> peritoneal
what is benign?
- well defined and similar structure to tissue of origin
- progresses slowly
