Path - Cell Injury + Cell Death (iii)

reasons for intracellular accumulation of an endogenous substance

production rate > removal rate

e.g. due to fatty liver

lipofuscin = lipid-rich pigment-like waste product that deposits in ageing tissues

storage diseases (substance can't be metabolised)

cells can't degrade certain exogenous substances (e.g. tattoo ink

Pathological calcification

abnormal deposition of Ca salts (with smaller amounts of Fe, Mg + other mineral salts)

2 types

1) dystrophic

2) metastatic

deposition in necrotic tissue (intra/extracellular), serum Ca levels normal

deposition in normal tissue + hypercalcaemia

e.g. hyperparathyroidism, bone destruction, vit D overdose, renal failure, sarcoidosis (collections of inflamm cells, granulomas in ling/skin/nodes)

primarily affects vessels, kidneys, lungs + gastric mucosa

2 theories for cellular aging

1) Wear + tear

ROS accumulate - metabolic + genetic damage

2) intrinsic cellular ageing / replicative senescence

predetermined genetic programming

telomeres shorten until cell arrest