Growth, Cell Death and Neoplasia Flashcards
define apoptosis
programmed cell death
define necrosis
traumatic cell death - unintended cell death in response to cellular injury
why do we need apoptosis?
for continuous renewal of cells, working alongside mitosis
name some inhibitors of apoptosis
growth factors
extracellular cell matrix
sex steroids
some viral proteins
name some inducers of apoptosis
growth factor withdrawal loss of attachment of ECM glucocorticoids some viruses free radicals ionising radiation DNA damage
give some examples of when apoptosis is crucial for normal growth - and what occurs if apoptosis fails
separating of fingers - interdigital cell death - syndactyl (webbed fingers)
removal of redundant epithelium on fusion of palatine processes in roof of mouth - cleft palate
what is coagulative necrosis?
most common.
dead tissue is swollen and firm, then later becomes soft - digestion of macrophages
what is colliquative (liquefactive) necrosis?
occurs in brain due to lack of supporting stroma - necrotic tissue liquefies
what is caseous necrosis?
dead tissue is completely structureless. histology shows amorphous eosinophilic area with haematoxyphilic nuclear debris.
seen in TB.
what is gangrene?
necrosis with putrefaction of tissues. tissues appear black.
what is fibrinoid necrosis?
occurs in malignant hypertension - increased arterial pressure results in necrosis of SM wall.
eosinophilic and fibrinous deposits seen.
what is fat necrosis?
focal adipose tissue destruction due to direct trauma, or enzymatic lipolysis (seen in acute pancreatitis)
define hypertrophy
increase in size of a tissue caused by increase in SIZE of the constituent cells
define hyperplasia
increase in size of a tissue caused by an increase in NUMBER of constituent cells - decrease in apoptosis
define atrophy
decrease in size of a tissue caused by a decrease in NUMBER or SIZE of constituent cells - apoptosis
define metaplasia
change in differentiation of a cell from one fully-differentiated type to another
define dysplasia
morphological changes seen in cells in the progression to becoming cancer
give some examples of physiological hypertrophy/hyperplasia
muscle hypertrophy in athletes - in limbs and LV of heart.
hyperplasia of breast tissue at puberty and in pregnancy/lactation.
hypertrophy and hyperplasia of uterine smooth muscle at puberty/pregnancy.
give some examples of conditions involving pathological hypertrophy/hyperplasia
RVH/LVH.
gynaecomastia.
prostate hyperplasia.
follicular epithelial hyperplasia e.g. in Graves’ disease (thyroid)
define congenital
present at birth - not necessarily inherited, foetus is affected by environmental factors in womb (eg FAS)
give some examples of changes to the body that are typical of ageing
loss of dermal elastosis osteoporosis cataracts senile dementia sarcopaenia (loss of skeletal muscle mass/strength) deafness
define carcinogenesis
transformation of normal cells to neoplastic cells through permanent genetic alterations or mututations
- malignant tumours
define oncogenesis
formation of benign and malignant tumours
define carcinogen
agents known/suspected to cause cancer - malignant tumours.
act on DNA - mutagenic
define oncogenic
agents known/suspected to cause tumours - benign or malignant
what problems are presented by attempts to identify carcinogens?
latent interval may be decades.
environment is complex - difficult to isolate one factor.
ethical constraints - can’t deliberately give people a suspected carcinogen as part of a study
list the classes of carcinogen
chemical viral ionising/non-ionising radiation hormones, parasites and mycotoxins misc.
define neoplasm
lesion resulting from autonomous (or relatively autonomous) abnormal growth of cells which persists after the initiating stimulus has been removed
A NEW GROWTH
what are the features of neoplasia?
autonomous
abnormal
persistent
new growth
what makes a neoplasm malignant?
if they invade surrounding tissues, and are able to metastasise/spread to other tissues
describe the structure of solid tumours
neoplastic cells + stroma
what induces stroma formation in a tumour?
connective tissue fibroblast proliferation is induced by growth factors produced by tumour cells
why is angiogenesis needed in tumours?
to perfuse the tumour, allowing it to grow - without angiogenesis, tumour may only grow to 1-2mm diameter
what induces angiogenesis in tumours?
vascular endothelial growth factor (VEGF) - secreted by tumour cells
describe the features of a neoplastic cell
derived from nucleated cells, usually monoclonal.
growth pattern relates to parent cell.
synthetic activity relates to parent cell - production of collagen/mucin/keratin/hormones etc
describe the features of a benign neoplasm
localised, non invasive.
slow growth rate, low mitotic activity.
closely resembles normal tissue.
necrosis/ulceration rare.
how might benign neoplasms cause problems?
pressure on adjacent structures. obstruction of flow. production of hormones. transformation to malignant neoplasm. anxiety.
describe the features of a malignant neoplasm
invasive.
metastases.
rapid growth rate.
variable resemblance to normal tissue - closer resemblance = better prognosis.
poorly defined/irregular border.
hyperchromatic nuclei, increased mitotic activity.
necrosis/ulceration common.
how might malignant neoplasms cause problems?
destruction of adjacent tissue. metastases. blood loss from ulcers. obstruction of flow. hormone production. paraneoplastic effects. anxiety.
what is a papilloma?
benign tumour of non-glandular, non-secretory epithelium.
prefix with cell type of origin.
what is a squamous cell papilloma?
benign tumour of squamous cell (non-glandular, non-secretory) epithelium