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Flashcards in Cellular Adaptations Deck (37)
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1

What 3 things affect cell population

Rate of cell proliferation
Rate of cell differentiation
Rate of deal death by apoptosis

2

What are 2 types of causes of cell proliferation

How are they related?

Physiological
Pathological

Excessive physiological can become pathological

3

In regards to the cell cycle , what are 2 ways increased tissue growth occurs?

- Shortening of cell cycle
- Conversion of quiescent cells to proliferating cells

4

How many key checkpoints are there in the cell cycle?

What are they? Which is the most critical?

Out of the 3, which is most commonly altered in cancer cells

3

- G1/ S
- G2/M
- Restriction Point (Towards end of G1), Most critical

In cancer, Restriction point

5

Compare the G1/ S and G2/ M checkpoints

G1/ S: Checks for DNA damage before replication

G2/ M: Checks for DNA damage after replication

6

What happens the the majority of cells that pass the Restriction point of cell cycle?

What happens if the checkpoint is activated?

Most will complete the cell cycle

If the checkpoint is activated, protein p53 arrests the cell cycle and triggers DNA repair mechanisms OR apoptosis

7

Which protein is called the guardian of the genome

P53

8

What proteins and enzymes control the cell cycle?

How are they linked?

Cyclins and Cyclin Dependent Kinases (CDKs)

CDKs become activated by binding to cyclins

9

How do ACTIVATED CDKs control the cell cycle?

Drive cell cycle by phosphorylation of proteins, that are needed for cell cycle to progress to next stage

10

What molecules regulate the activity of Cyclin-CDK complexes?

How do growth factors affect Cyclins and CDKs

CDK inhibitors

Growth factors either;
- Stimulate cyclin production
- Inhibit CDK Inhibitor production

11

What is the role of Retinoblastoma Protein?

Which cyclin/ CDK complex affects it and how?

- Prevents DNA Replication

- Inactivated by phosphorylation by Cyclin D/ CDK 4 complex

12

Name 3 molecules that stimulate cell proliferation

Name 2 that inhibit cell proliferation

- Oncogenes
- Cyclins/ CDK complex
- Growth factors

- CDK inhibitors
- Tumour suppressor genes

13

Define Cellular Adaptation

The reversible state between normal under stressed cell and injured over stressed cell

14

What are 4 ways cells can adapt?

- Hyperplasia
- Hypertrophy
- Atrophy
- Metalasia

15

How can Hyperplasia lead to Dysplasia?

If stimulus is not removed

16

Define Hyperplasia

In which 2 tissue types can it occur?

What are 2 types of reasons it can occur?

What can occur if cells divide repeatedly?

Increase in tissue/ organ size due to Increased Cell Numbers

- In labile and stable tissues
- Increased functional demand/ hormonal stimulation

Repeated cell division exposes cell to risk of mutation and neoplasia

17

Give 2 physiological and 2 pathological examples of Hyperplasia

Physiological;
- Proliferation of endometrium due to oestrogen
- Increased erythrocyte production by bone marrow due to hypoxia

Pathological;
- Epidermal thickening in Eczema/ Psoriasis
- Enlargement of thyroid gland in response to iodine deficiency

18

Define Hypertrophy

In which 3 tissue types can it occur?

What are 2 types of reasons it can occur?

How is the workload of the cell affected?

Increase in tissue/ organ size to increase in cell size

Labile, stable but especially permanent tissues

- Increased functional demand
- Increased hormonal stimulation

Workload is shared by more structural components

19

How are Hypertrophy and hyperplasia linked in labile and stable tissues

In labile and stable tissues, Hypertrophy usually occurs with hyperplasia

20

Give 2 physiological and 3 pathological examples of Hypertrophy

Physiological;
- Skeletal muscle in bodybuilders
- Smooth muscle of uterus during pregnancy (Hypertrophy and hyperplasia)

Pathological;
- Cardiac muscle hypertrophy
- Smooth muscle hypertrophy due to intestinal stenosis
- Prostate gland enlargement-> Urethra obstruction-> Bladder smooth muscle hypertrophy

21

What is Compensatory Hypertrophy?

Give an example

Increase in size of an organ/ tissue when needed to do additional work or to perform the work of a destroyed tissue/ paired organ

If one kidney is removed/ damaged

22

What happens to cells/ organs when the stimulus causing hypertrophy/ hyperplasia disappears

Returns to normal size

23

Define Atrophy

Shrinkage of a tissue/ organ due to increase in size and/ or number of cells to a size at which survival is possible

24

What is tissue atrophy usually a result of?

Is it reversible?

Usually a combo of cellular atrophy and apoptosis

Reversible up to a point

25

Other than cells, what can undergo atrophy?

How is atrophy best treated?

ECM can also undergo atrophy

Best treated by removal of the cause

26

Give 2 physiological examples of atrophy

- Ovarian atrophy in post menopausal women

- Decrease in size of uterus after child birth

27

Give 12 pathological causes of atrophy

- Reduced functional demand/ workload
- Loss of innervation
- Inadequate blood supply
- Inadequate nutrition
- Loss of endocrine stimuli
- Persistent injury
- Aging
- Pressure
- X rays
- Occlusion of a secretory duct
- Toxic agents/ drugs
- Immunological mechanisms

28

Define Metaplasia

Why does it happen?

Reversible change of one differentiated cell type to another

(In labile and stable tissues)

Adaptive substitution of cells that are sensitive to stress by cell types that are able to better withstand the adverse environment

29

What 2 things can metaplasia lead to?

When can metaplasia not happen

Can lead to dysplasia and cancer

No metaplasia across germ layers

30

Identify 3 examples of Metaplasia

- Myeloid metaplasia (Splenic tissue-> Bone marrow)

- Smoking->> Bronchial pseudostratified epithelium->stratified squamous

- Barret’s oesophagus (Stratified squamous in oesophagus-> Gastic/ intestinal epithelium due to persistent acid reflux)