Pathology Flashcards
hyperplasia
increase in cell number
(in response to a stimulus, regresses in stimulus withdrawal, results in increased organ VOLUME, can be physiological/ pathological)
atrophy
wasting away due to degeneration of cells
(reduction in cell size)
can be physiological / pathological
metaplasia
the replacement of a differentiated cell type with another differentiated cell type
define compensatory growth
a type of regenerative growth that can happen after the organs are damaged/ removed/ stop working. Can be increased size (hypertrophy) or increased mitosis (hyperplasia)
Occurs in liver, bone marrow
mechanism of hyperplasia?
increased production of growth factors
hormone may be a growth factor itself
increased growth factor receptors
switch on genes encoding growth factors and cell cycle regulators which promote growth
example of pathological hyperplasia?
prostate hyperplasia
abnormal menstrual bleeding due to excess oestrogen causing endometrial hyperplasia
when do lymph nodes physiologically undergo hyperplasia?
when fighting infection
hyperplastic tissue is an “at risk” site for cancer development. True/ False?
true
cancer will keep growing without a stimulus
could happen in endometrial cancer
hypertrophy
increase in cell size (NOT number)
often occurs in conjunction with hyperplasia
happens in cardiac myocytes, skeletal muscle
in response to mechanical stress
why does a hypertrophied heart eventually fail?
the heart can no longer function and needs more blood supply than it can get
when can pathological atrophy occur?
when there is decreased workload (e.g. leg in cast)
or
loss of innervation, and loss of function after nerve supply lost
can occur when there is a blocked blood supply to the brain (usually in association with atherosclerosis - thought to account for decreased brain size with ageing)
mechanism of atrophy?
reduced cellular components
protein degradation - digested in lysosomes and degraded by ubiquitin proteasome pathway
glucocorticoids and thyroid hormones promote degradation and atrophy
insulin opposes atrophy and promotes growth
a balance of growth and atrophy retain s homeostasis
mechanism of metaplasia?
it is not a change in appearance of a cell
it represents a change in signals delivered to stem cells causing them to differentiate down a different line
may be in response to cytokines, growth factors, and other chemicals in the microenvironment
commonly in response to a noxious stimulus
e.g. squamous metaplasia is common in response to injury in lung and salivary ducts
metaplastic tissue is an at risk site for cancer development. True/ False?
true
(even though there is no squamous epithelium in the lung, squamous cell cancer in the lung is common. Similarly, adenocarcinoma (gland forming tumour) is common in oesophagus despite there being no glandular epithelium in oesophagus)
