Cellular adaptation Flashcards
(76 cards)
How is cell cycle controlled? (3)
Cyclin protein & CDK enzymes!> form complex
Activated CDK’s Phophorylate protiens
ex: Retinoblastoma (Rb), that is critical fro the preogression of the cell cycle to the next stage!
This complex is controlled by GF or CDK inhibitors.

What can the chemical signals make the cell do?
Survive the 2 D’s

How can a cell population increase it’s numbers?
v
Can cells with damaged DNA replicate?
if there is damage to the DNA, or the DNA hasnt replicated, then the cell will try and fix it, if it cant fix it, it’ll push itself into aopotosis.
but in general NO. it cant replicate!
what is the most important check point in the cell cycle? where is it in the cell cycle
The restriction (R) point, near the end of G1!
after it passed the R point, the cell doesn’t need further signals to carry on, it can now complete the cell cycle on its OWN!
(cell isnt restricted anymore)

what is a telemere? telemorase
Telemorase is an enzyme that grows back the “telomeres” (plastic bit at the end of a shoe lace ;P)
they sit in the end of ur chromosome, and everytime a cell divides, they get shorter and shorter.
- old ppl have shorter teleomeres!*
- **cancer cells have telomerase! that keeps on putting the plastic end on the showlase so it’ll survuve longer!*

Are cellular adaptations reversible?
v
What is hyperplasia? In which types of tissues does it occur?
Increase in tissue or organ size due to increased cell #’s.
- Labile or stable tissues
- it is a response to increased functional demand or external stimulation.
- Remains under physiological control and is reversible
What examples are there of physiological hyperplasia?
- Bone marrow produces erythrocytes in response to response to LOW o2
- Proliferative endometrium under influence of oestrogen
What examples are there of pathological hyperplasia?
- epidermal thickening of in chronic eczema or psoriasis
- enlargement of thyroid gland in response to iodine deficiency GOITRE

What is hypertrophy? In which types of tissue does hypertrophy occur?
Increase in tissue or organ size due to increased cell SIZE and NOT #’s
- Labile, stable but especially permanent tissues bc permnenat tissues have no replicative potential, and so increase in size must occur via hypertrophy
- Like hyperplasia, caused by increased functional demand or hormonal stimulation
What examples are there of physiological hypertrophy?
- skeletal muscle of a body builder
- pregnant uterus (hypertrophy & hyperplasia)

What examples are there of pathological hypertrophy? (3)
- ventricular hypertrophy in response to hypertension or valvular disease.
- If u have stricture in the bowel. The area after the point of stricture is thickened!
- if u have an enlarged prostate gland, the muscle of ur bladder will work harder,….

But don’t athletes get cardiac muscle hypertrophy?
But that not a problem, bc after he’s done running, hes gunna lay down, and his heart can rest!

What is atrophy?
Shrinkage of a tissue or organ due to an acquired decrease in size and/or number of cells
What is happening in the cell in atrophy?
- Shrinkage in the size of the cell to a size at which survival is still possible
- cells contain Reduced structural components & reduced function
- May eventually result in cell death
A-trophia >> means lack of food.
shrinkage of a tissue or organ due to lack of nutrients and or GF
What examples are there of physiological atrophy?
- Ovarian atrophy in post menopausal women
- decresed size of uterus after child birth
Give example of atrophy that may occur in the pancreas
ex: ur pancreas is obstructed by a stone, it will cause the pancreas tissue to atrophy. the islets of langerhans get left behind. and fibrotic tissue is present.
Cerebral atrophy ex?
– Alzheimer’s disease
What examples are there of pathological atrophy?
-If u stopped using a muscle>> u get atrophy of a mUscle! It is reversible with imcreased activity! Reduced functional demand/workload = atrophy of disuse: muscle atrophy after disuse, reversible with activity
- Loss of innervation = denervation atrophy: wasted hand muscles after median nerve damage
- Inadequate blood supply: thinning of skin on legs with peripheral vascular disease
- Inadequate nutrition: wasting of muscles with malnutrition
- Loss of endocrine stimuli: breast, reproductive organs
- Persistent injury: polymyositis (inflammation of muscle)
- Aging = senile atrophy: brain, heart
- Pressure: tissues around an enlarging benign tumour (probably secondary to ischaemia)
***But some organs r protected ( ex brain. It is that last to get into malnutritiion!)
What is aplasia? give examples
Complete failure of a specific tissue or organ to develop
it is an embryonic developmental disorder
Eg:
- Thymic aplasia - infections and auto-immune problems
- Aplasia of a kidney
(Also used to describe an organ whose cells have ceased to proliferate, e.g. aplasia of bone marrow in aplastic anaemia)
What is hypoplasia? examples
Congenital Underdevelopment or incomplete development of tissue or organ at embryonic stage, inadequate number of cells.
In a spectrum with aplasia NOT opposite of hyperplasia as it is a congenital condition.
Cf atrophy which occurs when existing part wastes away.
Eg: Rena,l Breast , Testicular in Klinefelter’s syndrome. Chambers of the heart
What is metaplasia? examples ? Does metaplasia predispose to cancer?
Reversible replacement of one cell by another.
(the stem cells that r producing a specific type of cells SWITCH paths! and start producing a different line of cells)
-Metaplastic cells are fully differentiated and the process is reversible
**with smoking, u get change of the pseudostratified columnar cells into stratified squamous cells YES




