Cellular adaptations Flashcards
What 4 actions can the chemical signals that regulate cellular proliferation have on cells?
resist apoptosis
die
divide
differentiate
two ways in which a cell popn increases its numbers
shortening of the cell cycle
the conversion of quiescent cells into cells that enter the cell cycle (proliferating cells)
Two ways in which mitosis is regulated?
checkpoints- esp the restriction checkpoint (most critical checkpoint)
Cyclins and cyclin dependent kinases- Cyclins bind to cyclin dependent kinases to allow the cell to pass through to the next cell cycle change
If activated, what effects does the restriction checkpoint have on the cell? 3
delays mitosis
triggers DNA repair
Can trigger apoptosis
define hyperplasia
Increase in cell number
define hypertrophy
increase in cell size
define atrophy
decrease in cell size and number
define metaplasia
change of on differentiated cell type to another
In what types of tissue does hyperplasia occur and name two causes of it
labile and stable tissue
Causes: increased functional demand or hormonal stimulation
What is the risk of hyperplasia?
increases the risk of mutations and neoplasia development
Give two physiological examples of hyperplasia?
Bone marrow increases production of erythrocytes in response to hypoxia
proliferative endometrium under oestrogen influence
Give two pathological examples of hyperplasia?
goitre
eczema
In what type of tissue does hypertrophy occur
All types but especially permanent
two causes of hypertrophy?
increased functional demand or hormonal stimulation (same as hyperplasia causes))
WHat happens to the cell in hypertrophy?
increased number of structural compinents so that the workload is shared between a greater number of components
Define compensatory hypertrophy. Give an example of this
when one of two organs undergoes hypertrophy because the other organ has been injured so makes up for other organ
eg. a kidney transplant (the donor)
Name two physiological examples of hypertrophy
skeletal muscle
pregnancy
name two pathological examples of hypertrophy
bowel wall when the prostate gland compresses urethra
cardiac hypertrophy
What two processes usually occur in organ shrinkage
atrophy and apoptosis
give one example of physiologicaL ATROPHY
ovary after menopause
Give 8 examples of pathological atrophy
loss of innervation (Eg. median nerve damage leads to atrophy of muscle in the hand)
Loss of blood supply (EG. thinning of the skin in peripheral vascular disease)
Aging
Decreased demand or workload (Eg. disuse muscle atrophy)
Pressure (Brain tumour)
Inadequate nutrition
Decreased endocrine stimulation
persistent injury (Eg. chronic inflammation)
Give an examples of atrophy of the extracellular matreix
osteoporosis
What is metaplasia due to? What is it often a prelude to? In what tissues does it occur in? Between what types of layers do you not get metaplasia
altered stem cell differentiation
dysplasia and cancer
occurs in labile and stable tissue
you don’t get metaplasia across germ layers
Give three examples of metaplasia
Barretts Oesophagus: Stratified squamous epithelium to gastric glandular epithelium due to persistent acid reflux
Bronchial Pseudostratified epithelium –>stratified squamous epithelium due to cigarette smoke
Splenic metaplasia when bone marrow is damaged to take over the role of red blood cell production
