Lecture 11- Cellular Adaptations Flashcards
Mitosis vs cytokinesis?
Mitosis is nuclear division while cytokinesis is cellular division
G1 and G2 checkpoint?
G1 looks at is cell big enough
, is environment favourable and is DNA damaged
G2 looks at if All dna is replicated properly and is cell big enough
What is the restriction point?
At end of G1 it’s the most critical checkpoint in cell cycle
Point of no return and so is most commonly affected in cancer
Activation triggers apoptosis or repair through P53 protein
What activates restriction point and what occurs as a result?
Dna damages, hypoxia, telomere attrition etc.
Results in cell senescence, inhibits angiogenesis to starve cell, apoptosis etc through p53 protein
Give an example of a tumour suppressor gene?
P53
Cyclone and CDK?
Change in level throughout cell cycle and help it to proceed in orderly fashion
Retinoblastoma protein?
Acts to prevent DNA replication. Mutation means DNA replication uninhibited. Patients get retinoblastoma first usually
What determines cell population size?
Cell proliferation against cell death or differentiation etc
How are cell populations controlled?
Different combinations of different external signals will cause them to divide, survive, differentiate or die etc
Hyperplasia?
Increased in organ or tissue size due to increased cell number
Why does hyperplasia occur?
Hormonal or compensatory
Physiological= endometrium proliferation in response to oestrogen
Pathological= eczema
Hyperplasia?
Physiological= skeletal muscle growth
Pathological= right ventricular hypertrophy
Compensatory hypertroph?
Remove one kidney other enlarges to compensate
Physiological atrophy?
Ovaries post menopause
Pathological atrophy causes?
Disuse
Disinnervation
Reduced hormonal stimulation
Malnutrition
Inadequate blood supply
Aging (senile atrophy)
Pressure from adjacent tumour etc
Metaplasia?
Reversible change of one differentiated cell type to another
Eg pseudostratified respiratory epithelium to stratified squamous
Can lead to dysplasia and then cancer
Aplasia?
Complete failure of tissue or organ to develop eg aplastic anaemia no bone marrow
Hypoplasia?
Under development of tissue or Ryan at embryonic stage, inadequate cell number
Congenital condition so not opposite of hyperplasia
Eg chambers of heart
Involution?
Normal programmed shrinkage of an organ eg uterus after childbirth
Reconstitution?
Replacement of lost part of body eg angiogenesis
Atresia?
No orifice or opening
Congenital
Eg anus and vagina
Dysplasia?
Abnormal maturation of cells in tissue
Potentially reversible and often pre cancerous
