14. Cellular Adaptation

Question 1

what kind of changes does cellular adaptation include?

Answer 1

1. size
2. number
3. phenotype
4. metabolic activity
5. function

Question 2

why do cells need to adapt?

Answer 2

due to changes in the environment or demand

Question 3

what is the purpose of cellular adaptation?

Answer 3

to acquire a new, steady state of metabolism and structure
better equips cells to survive in a new environment
failure of adaptation may lead to sub-lethal or lethal cell injury

Question 4

what determines a cell’s susceptibility to damage?

Answer 4

the type of cell it is -
labile and stable populations adapt easily due to active stem cell population
some cells don’t need to adapt, they survive severe metabolic stress without harm
permanent cells cannot adapt, they are terminally differentiated and have a highly specialised function. easily damaged by environmental change

Question 5

what are the 2 types of cellular adaptation?

Answer 5

physiological - responding to normal changes in physiology or demand
pathological - responding to disease related changes

Question 6

what are the 3 types of cellular adaptive response?

Answer 6

1. increased cellular activity
2. decreased cellular activity
3. change of cell function and morphology

Question 7

how can cells increase activity?

Answer 7

1. hypertrophy- increases synthesis of structural components and metabolism. characteristic of permanent cell populations (cardiac and skeletal muscles)
2. hyperplasia - possible in stable and labile populations
   these 2 can co-exist.
   these 2 don’t only exist on a cellular level, sub-cellular components can also become enlarged

Question 8

how can cells reduce activity?

Answer 8

decrease size of cells

decrease number of cells

Question 9

what is atrophy?

Answer 9

reduction in size of an organ or tissue by decrease in cell size and number. this can either be physiological or pathological
BUT not all reduced cell mass is due to atrophy, it can also be related to developmental abnormalities

Question 10

examples of pathological atrophy

Answer 10

1. decreased workload - disuse atrophy
2. loss of innervation - denervation atrophy
3. diminished blood supply
4. inadequate nutrition
5. loss of endocrine stimulation
6. pressure

Question 11

what are the mechanisms of atrophy?

Answer 11

1. reduction in volume of individual cells, leaving behind a residual body
2. death of individual cells, via apoptosis or involution

Question 12

what is involution?

Answer 12

physiological atrophy by apoptosis

Question 13

what is metaplasia?

Answer 13

transformation of one differentiated cell type into another

eg. transdifferentiation of stem cells

Question 14

what is the consequence of metaplasia?

Answer 14

better adaptation to new environment

it may form the basis on which neoplasia develops

Question 15

which tissues can adapt by metaplasia?

Answer 15

epithelium and mesenchymal tissues

Question 16

is metaplasia physiological or pathological?

Answer 16

both

Question 17

what metaplastic effect does cigarette smoke have on the body?

Answer 17

pseudo stratified ciliated cells of the airway -> squamous

Question 18

what metaplastic effect do calculi, bladder catheters and schistosomiasis have on the body?

Answer 18

transitional epithelium -> squamous

Question 19

what metaplastic effect does chronic trauma have on the body?

Answer 19

fibrocollagenous tissue -> bone

Question 20

what metaplastic effect does acid reflux have on the body?

Answer 20

squamous -> columnar

Question 21

what is dysplasia?

Answer 21

the enlargement of an organ or tissue by the proliferation of cells of an abnormal type, as a developmental disorder or an early stage in the development of cancer. it is the earliest morphological manifestation of multistage process of neoplasia

Question 22

is dysplasia reversible or irreversible?

Answer 22

irreversible

Question 23

what is the difference between dysplasia and malignancy?

Answer 23

it is an in-situ disease, non-invasive

shows cytological features of malignancy but there is no invasion

Question 24

what is another term for carcinoma in situ?

Answer 24

severe dysplasia