Cellular Adaptations Flashcards
What genes regulate cell proliferation
Proto-oncogenes
What controls cell proliferation
Chemical signals
How is the cell cycle changed to increase growth
- shortened cell cycle
- conversion of quiescent cells to proliferating cells
What prevents damaged cells from replicating
Checkpoints which will try to fix mistakes or induce apoptosis
What is the restriction point
The most critical checkpoint during G1 where the majority of cells which pass will enter the cell cycle
Which check point is most commonly altered in cancer cells
The restriction point
What is p53
A protein involved in apoptosis
What enzymes control the cell cycle and how do they do this
Cyclin dependant kinases become activated when binding to cyclin allowing them to phosphorylate their target protein to allow for the cell cycle
Give an example of a target protein phosphorylated by CDK
Retinoblastoma target protein
What is the hayflick constant
The number of time which a cell without telomerase can divide - 61.3
What is hyperplasia
Cells increase in number above normal
What is hypertrophy
Where cells increase in their size
What is atrophy
Where cells shrink to a size at which survival is still possible by reducing their cellular components. This may eventually result in cell death
What is metaplasia
Where cells are replaced by cells of a different type
Are cellular adaptations reversible
Most are except atrophy
In what tissue types does hyperplasia occur
Labile or stable tissue
What causes hyperplasia
Increased functional demand or hormonal stimulation
What do repeated cell divisions in hyperplasia put the cells at risk of
Mutations and neoplasia
Give 2 examples of physiological hyperplasia
- proliferation of endometrium due to oestrogen
- bone marrow production of RBCs in hypoxia
Give 2 examples of pathological hyperplasia
- goitre
- eczema
What tissue types does hypertrophy occur
Lability, stable, permanent
Give 2 examples of physiological hypertrophy
Skeletal muscle growth
Uterus in pregnancy
Give 3 examples of pathological hypertrophy
- ventricle hypertrophy due to hypertension
- in the bladder due to an enlarged prostrate
- in the bowel due to strictures
Why does hypertrophy in athletes hearts not become pathological
The heart rests afterwards
In pathological hypertrophy the heart doesn’t rest and is constantly growing. This means there will not be enough blood supply to the heart causing hypoxia
What is compensatory hypertrophy
When part of an organ or 1 of a pair of organs is damaged so the other will enlarge
Give a physiological example of atrophy
Ovarian atrophy in post menopausal women
Decrease in uterus size art child birth
Give some pathological causes of atrophy
- muscle atrophy after disuse
- loss of innervation
- inadequate blood supply
- inadequate nutrition
- los of hormonal stimuli
- ageing
- pressure
What is metaplasia
Reversible change of one differentiated cell type to another
Tru or false: metaplasia can occur across germ layers
False
What tissue types does metaplasia occur
Labile or stabile
Give 4 examples of metaplasia
- bronchial pseudostratified ciliated to stratified Squamous epithelia in smokers
- acid reflux causing stratified Squamous to glandular epithelium
- Spleen changing to produce RBCs when bone marrow is damaged
- injury to skeletal muscle
How metaplasia occurs when there is injury to skeletal muscle
Fibroblasts change to osteoblasts and deposit new bone - this is reversible
Does metaplasia predispose to cancer
Yes - Barrett’s epithelium can result in oesophageal adenocarcinoma
What is aplasia
An embryonic development disorder where there is failure to a specific tissue or organ to develop
Or an organ who’s cells have stoped proliferating
What is hypoplasia
Underdevelopment or incomplete development of a tissue or organ at embryonic stage
What is involuntion
Normal programmed shrinkage of an organ e.g. The thymus
What is reconstitution
Replacement of a lost part of the body
What is atresia
Where there is no orifice
What is dysplasia
Abnormal maturation of cells in a tissue
