disorders of growth Flashcards
response of cell to disease/injury depends on
how much injury
how vulnerable the cell is to injury
responses of cell to stress
adaptation
injury
cell injury
- where the dose is too large and the cell cannot adapt
- irreversible damage
cell adaptation
metabolic
structural
atrophy
decrease in cell size
decrease in cell number
hypertrophy
increase in cell size
hyperplasia
increase in cell nuumber
metaplasia
change in how they differentiate
labile cells
cells continually divide
in cell ccle
permanent cells
after development they have left cell cycle
no longer can divide
if injured or die cannot be reaplced
quiescent cells
cells that are not normally dividing
retained ability to divide
too much growth causes
1) Developmental
- hamartoma
2) Reactive/adaptive
- hyperplasia
- hypertrophy
hartoma
tumour like overgrowth
- tissues are normal for sit but excessive
stop growing after growth period
what does hyperplasia occur to and lead to
response to stimulus
regression once stimulus removed
increased size and function
chronic irritation/inflammation effects
lots of inflammatory mediators
causes cells to divide
endocrine hyperplasia
1) Physiological
- normal growth and development
- puberty and pregnancy
2) pathological
- parathyroid (glands in the neck, produces hormones)
- thyroid
ventricular hypertrophy
- heart has to work harder to pump the blood around the body
- therefore the heart has to increase its muscle cell size to pump the blood around the body
- muscle wall of the LHS increases in thickness in attempt to push against the high BP
- This can become pathological when the heart is as big as it can get
neoplasia
growth which is uncontrolled and does not stop and persists after the stimulus has moved
(hyperplasia/trophy is under normal conditions when stimulus is removed returns to normal)
developmental conditions with too little growh
agenesis
aplasia
hypoplasia
agenesis
extreme of too little growth at all
e.g. missing 3rd molars
aplasia
forms but not to its full structure
hypoplasia
structure forms but it is deficient in its capacity
e.g. enamelhypoplasia
mechanisms of atrophy
imbalance of cell loss and production
- reduced proliferation
- apoptosis rather than necrosis
- reduction in structural components of the cell esp protiens
generalised atrophy
1) Nutritional
- starvation
- start to break down the tissues, fat and muscle
2) Age related(senile)
- with age tend to shrink a bit
3) Endocrine
- usually due to removal of hormone
- eg reduction in levels of oestrogen during menopause
- leads to generalised atrophy of bone
4) Bone
- osteoporosis
- density of the trabeculae bone is reduced
localised atrophy
1) Ischaemic
- reduction in blood supply to organ or part of the body
2) pressure
- sustained pressure at a part in the body
- eg pressure sores from being immobile for a period of months
3) disuse
- reduction in muscle mass as they are not being used
4) neuropathic/denervation
- reduction in muscle mass as they are not being used
- nerve damage can lead to a reduction in the muscle the nerve supplies
5) immune mediated (autoimmune)
- body raises an immune repsonce to a specifc tissue
6) Idiopathic
- cause unknown
atrophic mandible issues
without teeth alveolar bone will shrink back
harder to place a denture on the ridge
metaplasia
change in differentiation
- change within the same germinal layer
results from environmental demands
example of metaplasia
mucus metaplasia
e.g. squamous metaplasia in brooch of smokers due to irritation of smoke, not usually sqamous
prevention of original job to secrete mucus and cilia
dysplasia
Abnormal growth and differentiation in a tissue with abnormal cells and tissue architecture
- May be premalignant, higher risk of becoming cancer
- overall growth of the cell is abnormal
ectopia
Tissue gets to the wrong place
- developmental abnormality
- normal tissue, abnormal site
