1.4 Adapatation to Injury and stress Flashcards
Hypertrophy
increase in size of cells leading to an increase in size of tissue
Physiological hypertorphy
Uterus during pregnancy–>SM cells get largers (but note these cells can also divide)
Skeletal muscle–>by over working
Pathological hypertrophy
heart because of hypertension–>short term this is good to pump against a pressure gradient but in the long term that’s a problem
Causes of hypertrophy (3)
Mechanical stimulus - cardiac and skeletal muscle hypertrophy
Growth factor stimulation - endocrine stimulation at puberty - not a good example
increased functional demad - unilateral nephrectormy –>take out one, other one grows–glomeruli get huge
In Myocardial hypertrophy the size
increases
What happens to ANF in myocardial hypertrophy
it is normally not expressed but gets expressed to decrease cell volume, lowering load and lowering pressure
Proteins expressed in Myocardial hypertrophy (6)
c-fos, jun, EGRF, fetal contractile proteins (beta myosin-more energy efficient but dec atpase activity), growth factors (TGF -beta, IGF -1)
What is the end result of myocardial hypertrophy
degeneration
The hearts of well trained athletes have vs myocardial hypertrophy
good ability to dialate and increase stroke volume vs only an increase in heart rate
Hyperplasia
inc in no. of cells resulting in inc size
Physiological hyperplasia
lactating breast
Pathological hyperplasia
overstimulation by hormones e.g. enlargement of the prostate; inc risk of cancer
Causes of hyperplasia
viral induced - warts
growth factor stimulation - endocrine or stress- induced
ex.
- endometrial proliferation with each menstral cycle
- callus formation
- erythroid hyperplasia under chronic hypoxic conditions
Atrophy
decrease in size and often fn of cells, generally associated with a decrease in size and or fn of a tissue or organ
Causes of Atrophy (7)
Disues atrophy of muscle - voluntary or denervation-induced
dec blood supply
inadequate nutrition
loss of endocrine stimulation
loss of growth factors
aging
pressure
Mechanisms of atrophy
inc catabolism
inc ubiquiting proteosome pathway
inc lysosomal degredation