2. Cell response to injury: Morphological Changes 2 Flashcards
how can labile and stable cells alter their pattern of growth?
- size
- differentiation
- number
2 mechanims in which cells respond to an increase in functional demand?
hyperplasia and hypertrophy
which 3 cells is hyperplasia not seen in? why?
cardiac, skeletal and neuronal cells - they are permanent cells
3 examples of physiological hyperplasia
- bone marrow
- glandular epithelium/endometrium
- puberty + pregnancy
in what circumstances does bone marrow hyperplasia occur?
in high altitude with low oxygen - stimulates erythropoiesis
in what circumstances does glandular epithelium/endometrium hyperplasia occur?
menstrual cycle
in pregnancy and puberty - which cells undergo hyperplasia?
breast and myometrial smooth cells
in what 2 organ donations does compensatory hyperplasia occur?
liver and kidney
which 3 GF allow the liver to regenerate?
TGF-alpha
Hepatocyte GF
IL-6
which 2 growth inhibitors prevent liver regeneration?
TGF-beta
IL-1
2 causes of pathological hyperplasia?
- excess GF/hormones/GH receptors
2. up-regulation of cell-signalling systems
2 examples of pathological hyperplasia?
- graves disease - thyroid
2. benign prostatic hyperplasia
what is graves disease?
increased secretion of TSH causing increased thyroid hormones
what is benign prostatic hyperplasia?
increase androgens
2 ways in which hypertrophy occurs?
- increased synthesis of structural components
2. increased RNA synthesis and organelles required for protein synthesis
which cell type is hypertrophy only seen in?
permanent/non-dividing cells
2 causes of hypertrophy
- increased functional demand
2. stimulation of hormones/GF
2 examples of physiological hypertrophy?
- skeletal muscle in athletes
2. smooth muscle - pregnancy
what occurs in skeletal muscle hypertrophy in athletes?
increase in length and width of muscle fibres
what causes skeletal muscle hypertrophy in athletes?
increased work load
in skeletal muscle hypertrophy - what occurs if the stimulus (weight) is ceased?
the muscle size returns to normal
what causes smooth muscle hypertrophy in pregnancy?
oestrogenic hormones bind to oestrogn receptors
1 example of pathological hypertrophy?
cardiac muscle hypertrophy
3 cause of cardiac muscle hypertrophy?
chronic haemodynamic overload, hypertension, faulty valves
what is atrophy?
decrease in cell size
what is involution?
decrease in cell size and number
what 2 changes does involution/atrophy lead to
- decreased cell metabolism
2. decrease protein synthesis
which cells undergo atrophy?
permanent
which cells undergo involution?
stable and labile
3 examples of physiological atrophy/involution?
- loss of endocrine stimulation
- embryological structures
- thymus gland
give an example of atrophy/involution due to loss of endocrine stimulation?
menopause - loss of oestrogen stimulation causes atrophy of endometrium of vagina and breast tissue
give an example of atrophy/involution of embryonic structures?
notochord
when does the thymus gland involute?
adolescence
3 examples of pathological atrophy/involution
- decreased workload
- denervation
- lipofusion
give an example of atrophy/involution in terms of decreased workload?
immbolisation after fractured bone
what is lipofusion in cellular atrpohy?
the build up of lipofuscin - which is the breakdown product of myocardial fibres as a result of atrophy
what is agenesis?
absence of tissue/organ due to them not developing
what is hypoplasia/aplasia
failure in development of normal sized organ
describe hypoplasia/aplasia in aplastic anaemia
- hypofunction of BM
- Stem cells not produced
- pantocytopenia
- BM replaced by fat
