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Pathological Processes > 7. Cellular Adaptations > Flashcards

7. Cellular Adaptations Flashcards

1
Q

What 3 processes influence the size of a cell population?

A

Rate of proliferation, cell differentiation and cell death by apoptosis.

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2
Q

Which genes regulate normal cell proliferation?

A

Proto-oncogenes

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3
Q

What 2 processes could lead to an increase in cell numbers?

A

Increased proliferation or decreased cell death.

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4
Q

Name the phases of the cell cycle, in the correct order.

A

G1, S, G2, M

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5
Q

What happens to cells which exit the cell cycle?

A

Enter G0 until further growth signals occur.

Can undergo terminal differentiation where there is a permanent exit from the cell cycle.

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6
Q

What 2 mechanisms can lead to increased growth of a tissue?

A
  1. Shortening of cell cycle

2. Conversion of cells in G0 to proliferating cells, making them re-enter the cell cycle.

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7
Q

Which phase of the cell cycle is visible under a light microscope?

A

Mitosis

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8
Q

What is the name given to the cell cycle between M phases?

A

Interphase

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9
Q

How is cell cycle progression controlled?

A

Checkpoints - sense damage to the DNA, ensuring cells with damaged DNA do not replicate.

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10
Q

What is the most critical cell cycle checkpoint? Explain its significance.

A

The restriction (R) point towards the end of G1. The majority of cells that pass this point will go on to complete the cell cycle - no more signals are needed.

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11
Q

What occurs if checkpoints are activated (e.g by DNA damage)?

A

P53 protein - suspends cell cycle, triggers DNA repair mechanisms, if damage irreparable then trigger apoptosis.

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12
Q

Other then R, where are the other checkpoints in the cell cycle and what are their main functions?

A

G1/S transition - checks for DNA damage before replication

G2/M transition - checks for DNA damage after replication

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13
Q

Defective cell cycle checkpoints are associated with which disease?

A

genetic instability in cancer cells.

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14
Q

Which enzymes play a role in the control of the cell cycle?

A

Cyclin-dependent kinases (CDK)

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15
Q

What is the name of the proteins which bind to the CDK enzyme to control the cell cycle?

A

Cyclins

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16
Q

How do CDK and cyclins control the cell cycle?

A

Cyclin binds to CDK, activating the enzyme. The activated kinase phosphorylates proteins to drive the cell cycle.

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17
Q

What is hyperplasia?

A

Growth by increasing cell number

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18
Q

Which tissues can undergo hyperplasia?

A

Stable and labile

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19
Q

What causes hyperplasia and hypertrophy?

A

Increased functional demand or hormonal stimulation

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20
Q

What is a physiological example of hyperplasia?

A

Proliferation of bone marrow to produce erythrocytes in response to hypoxia.
Proliferative endometrium under oestrogen influence

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21
Q

What is a pathological example of hyperplasia?

A

Thryoid goitre

Eczema - epidermis hyperplasia

22
Q

What is hypertrophy?

A

Increase in tissue or organ size due to increased cell size

23
Q

Which tissues undergo hypertrophy?

A

Particularly permanent tissues

Stable and labile too usually in combination with hyperplasia.

24
Q

What is an example of physiological hypertrophy?

A

Skeletal muscle

Pregnant uterus - hypertrophy of SM cells

25
Q

What is an example of pathological hypertrophy?

A

Cardiac hypertrophy

If enlarged pancreas, SM of bladder hypertrophies due to increased resistance

26
Q

What is an example of compensatory hypertrophy?

A

If one kidney is removed or damaged, the other enlarged by both hyperplasia and hypertrophy

27
Q

What is atrophy?

A

Shrinkage of a tissue/organ due to decrease in size and/or number of cells

28
Q

What may be visible under an electron microscope in cells undergoing atrophy?

A

Residual bodies - packing of inessential components of the cell

29
Q

What is an example of physiological atrophy?

A

Ovarian atrophy in post-menopausal women

Uterus after childbirth

30
Q

What is an example of pathological atrophy?

A

Disuse atrophy
Denervation atrophy
Inadequate blood supply
Ageing

31
Q

Is atrophy reversible?

A

Yes, up to a point…

32
Q

What is metaplasia?

A

Change of one differentiated cell type to another due to altered stem cell differentiation

33
Q

Is metaplasia reversible?

A

Yes

34
Q

What cellular adaptation can be a prelude to dysplasia and cancer?

A

Metaplasia

35
Q

When might metaplasia occur?

A

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

36
Q

Does metaplasia occur across germ layers?

A

No.

E.g epithelium -> epithelium

37
Q

What tissues can undergo metaplasia?

A

Stable or labile

38
Q

How can smoking cause metaplasia, what is a possible long term complication?

A

bronchial epithelial changes from pseudostratified columnar, ciliated epithelium to stratified squamous epithelium.
Can lead to squamous cell carcinoma.

39
Q

Other than smoking, what is another example of metaplasia?

A

Barrett’s oesophagus - stratified squamous epithelium becomes gastric glandular epithelium in response to gastric reflux.

40
Q

How does the spleen demonstrate metapalsia?

A

Myeloid metaplasia - Extramedullary haemotopoiesis to produce blood cells

41
Q

Barretts oesophagus is linked to which cancer?

A

Oesophageal adenocarcinoma

42
Q

Intestinal metaplasia of the stomach is linked to which cancer?

A

Gastric adenocarcinoma

43
Q

What effect does tamoxifen have on the endometrium?

A

Can cause endometrial hyperplasia and progression to endometrial cancer.

44
Q

What are some common causes of LV hypertrophy?

A

Aortic stenosis, Hypertension, IHD, Mitral regurgitation, aortic regurgitation.

45
Q

How does LV hypertrophy increase risk of sudden death?

A

No increase in capillary numbers, so increased oxygen demand which is not met by an increased supply.
Fibrous tissue can cause arrhythmia and failure.

46
Q

What are some common causes of cerebral atrophy?

A

Alzheimer’s disease

Huntington’s disease

47
Q

What is a common cause of intestinal metaplasia of the stomach?

A

Chronic Helicobacter pylori infection

48
Q

What function is lost when bronchial squamous metaplasia occurs?

A

Mucus secretion and cilia to waft mucus along,

49
Q

What metaplasia occurs in columnar epithelium lining ducts secondary to chronic irritation by stones, how is this beneficial?

A

Stratified squamous epithelium- more resistant to mechanical abrasion

50
Q

Give an example of when flat, non-secreting epithelium is replaced by secreting epithelium?

A

Lower oesophagus in Barrett’s oesophagus

Pathological Processes (12 decks)

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