Cellular adaptation Flashcards
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
What is dysplasia?
abnormal maturation of cells w/ in the tissue. it is reversible. but is often a precancerous condition
What happens in tissue atrophy?
the cell is getting rid of these bits and pieces that it can do without and puts them in this autophagosome : RESIDUAL BODIES” dust bins
What is involution?
Overlaps with atrophy
Normal programmed shrinkage of an organ
- Uterus after childbirth,
- thymus* -in early life, pro- and mesonephros
which organs r protected from atrophy during malnutrition?
Brain
what is senile atrophy?
wasting of tissues and organs with advancing age
what is senile atrophy? what can cause it
wasting of tissues and organs with advancing age.
- old ppl have damaged DNA
- old ppl have cells that can no longer divide
How can pressure cause atrophy? ex in brain
If enlarging benign tumor (meningioma) in brain pushes the tissues around it.
what is meningioma?
Benign tumor of brain.
those cells that r put into stress, and they r adapted by becoming cells that r able to COPE better with that stress. REVERSIBLE
metaplasia
can u get metaplasia across germ layers?
no! its most commonly epitheliala to epithelia.
how does smoking effect ur epithelium?
Bronchial pseudostratified ciliated epitheliumstratified squamous epithelium due to effect of cigarette smoke
what is Barrett’s oesophagus
normally ur oesophagus is lined stratified by squamous epithelium, but is u get ACID REFLUX, the stratified squamous epithelium doesn’t like that and will undergo METAPLASIA into gastric glandular epithelium
what is traumatic myositis ossificans?
if use had a traumatic injury, and u start to exersize and go back to what u were doing tooo soon…….. fibroblasts can undergo metaplasia into osteoblasts! SHIITT and can produce bone IN THE FREAKING MUSCLE! this is reversible with rest
In what case would the spleen undergo metaplasia? what is this type of metaplasia called
if you’ve had damage to ur bone marrow, the spleen can undergo metaplasia and take the BM function. Myeloid dysplasia
why should ppl w/ barrets oesophagus be kept under servailiance?
bc it can develop into oesophageal adenocarcinoma
intenstinal metaplasia of the stomach ( stomach develops an epithelium like the intestines)
why? we don’t know and no one cares ok?
what happens when heart becomes pathological hypertrophic? (ya3ny how will it respond to this change)?
the heart will respond to that by growing more capillaries, but it can never grow ENOUGH to compensate. so the heart will always be hypoxic> damage to cells> fibrosis> heart can’t pump properly.
What general term is applied to this process in which an organ or tissue becomes smaller?
atrophy
What term is applied to atrophy which results from obstruction of the duct leading from an organ?
pressure atrophy
condition in the kidney, when ureteric obstruction has lead to pressure atrophy of the renal parenchyma?
It’s called hydronephrosis. The name refers to the fact that the renal pelvis becomes distended with fluid (urine). We say that the kidney is hydronephrotic. Hydronephrosis is often bilateral. This is an important consequence of longstanding obstruction to the outflow of urine from the bladder, with raised pressure causing pressure atrophy of both kidneys.
Sometimes an organ like the kidney starts off small from birth and never develops fully. What term would we apply to this process?
hypoplasia. “hypoplastic kidney”
but what do we call complete failure of development of an organ or tissue?
agenesis.
What name do we apply to atrophy due to lack of use of a tissue or organ?
disuse atrophy.
if a tissue undergoes atrophy following a period of disuse, is it possible for the process to become reversed if the tissue can be used once more.
yes> seen in muscles
What name do we give to atrophy due to destruction of the nerve supply?
This is called neurogenic atrophy.
when can u get neurogenic atrophy? give example
Patients with, for example stroke, multiple sclerosis etc. all get neurogenic atrophy of skeletal muscle.
Longstanding ischaemic atrophy of the neurones of the brain leads to deteriorating intellectual function, which is known as ______
dementia.
In someone dying of cancer, there is often widespread wasting of muscle. What name do we give to this?
Cachexia Patients with advanced cancer often develop cachexia: we say that they become cachectic.
What do we call atrophy of bone?
Osteoporosis. In osteoporosis, the amount of bone becomes reduced, although there is normal mineralisation of the bone that is there.
describe process of cell atrophy
as the cells atrophy the excess lipid that accumulates when the cell removes bits of membrane is packaged within vacuoles in the cytoplasm. So if we see lots of lipofuscin pigment in the cytoplasm of cells we can say that the cells must have atrophied. Lipofuscin pigment commonly accumulates in cells, such as myocardial cells, macrophages in the colon, etc. It’s commonly a sign of atrophy due to aging.
The main causes of atrophy are:
Pressure. Disuse. Neurogenic. Ischaemic. Nutritional. Endocrine.
what are two reasons why a tissue might atrophy?
There are two reasons why a tissue might become small: 1) Reduced number of cells.> due to apoptosis 2) Reduced size of cells.>ipid peroxidation of cell membranes.
__________tissues have no replicative potential, and so increase in size must occur via hypertrophy
Permemnat
under the microscope, which of the cell cycle phases is distinctive?
M phase
Includes: mitosis and cytokinesis
Label the changes
what is the most commonly altered checkpoint in the cell cycle in CANCER?
the restriction R point
How is p53 involved in cancer?
It is the guardian of the GENOME.
The p53 gene is a tumor suppresser gene involved in the regulation of the cell cycle, DNA repair, and programmed cell death. f the p53 gene is not functional and thus apoptosis does not occur,
cancer cells proliferate along with their mutations!
what is our average hayflick #?
61.3
define cellular adaptation
what r the 5 important types of cellular adaptaion?
the state btw normal unstressed cell & overstressed injured cell.
- Regeneration
- hypertrophy
- hyperplasia
- atrophy
- metaplasia
Define regeneration
replacement of cell losses by identical cells in order to maintain the size of a tissue and organ.
give example of compensatory hypertrophy
ex: when u have a kideny removed, or u were jsut born with a tiny kidney, the OTHER kideny enlarges to compensate.
what tissues or organs have very good regenerative capacity?
which have poor or none?
Good> liver, epithelia, bone, smooth muscle
Poor> tendons, articular cartilage
NONE> adipocytes, CNS
reconsistuation vs regeneration
Atrophy more often than hypertrophy is linked w/ disease!
ok
absence or abnormal narrowing of an opening or passage in the body
define term
atresia
ex: atresia of deudonem in babies
What is a pipelle biopsy?
takes a small sample of tissue from the lining of the womb (endometrium).
This sample is then sent off to the laboratory to check if you have any cancer or other abnormal cells in the lining of your womb ,
describe the condition
cerebral Globar atrophy
larger sulcus and smaller gyrus
globar ( cuz it effect ALL the brain)
how does atrophy differ from involution & hypoplasia
Involution overlaps with atrophy!
but atrophy is mostly linked with disease. while involution is the normal programmed shrinkage of an organ
Hypoplasia= is the congential underdevelopment or incomplete development of a tissue or organ
Ex: testicular hypoplasia is kleinfelters syndrome.
what type of cells r our brionchi lined with?
wt is their fucntions?
pseudostratified ciliated columnor
sweep cilia containing dust/ microbes our of the lungs
What is Tamoxifen?
what is it commonly used for?
antiestrogenic in the breast which blocks estrogen recepters and hence the proliferative action of estrogen!
used to treat breast cancer!
BUT, w/in the endometrium, itacts as an agonist at estrogen recepters>>this can result in
ENDOMETRIUM HYPERPLASIA
*
what is the RB retinoblastoma?
is a protein that when is phosphorylated by the Cyclin and CDK complex>> cell cycle will progress!
if the restriction (R) point has been activated, what does this mean?
it means that the cell has sensed some damage to its DNA
result in increased production of p53 (gardian of the genome)
it will delay the cell cycle in attempt to mend the DNA
