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Path Processes > Cellular Adaptions > Flashcards

Cellular Adaptions Flashcards

1
Q

What is the only stage of the cell cycle that can be seen by light microscopy?

A

Mitosis

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2
Q

Where is the most important checkpoint in the cell cycle and what is it called?

A

The Restriction Point

Found towards the end of G1

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3
Q

In terms of the cell cycle, by which 2 ways can increased growth of a tissue occur?

A

1. Shortening the cell cycle

2. Conversion of quiescent cells to proliferating cells by re-entering the cell cycle

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4
Q

What protein comes into play if the restriction point is activated?

A

p53 ‘guardian of the genome’

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5
Q

Give some of the actions of p53

A
  • senescence
  • cell-cycle arrest
  • migration
  • apoptosis
  • DNA repair
  • Metabolism
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6
Q

Explain how cyclins and CDK’s control progression through the cell cycle

A
  • cyclins bind to CDKs which causes them to activate
  • actived CDKs phosphorylate proteins to drive the cell cycle
  • CDKI (inhibitors) tightly regulate CDKs
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7
Q

What is the normal function of Retinoblastoma protein?

A

Rb holds on the proteins, therefore stops cell cycle progression i.e. it is a TUMOUR SUPPRESSOR GENE

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8
Q

How many mutations of Rb are required to inactive it’s function?

A

2 mutations (1 in each Rb allele)

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9
Q

How is Retinoblastoma protein inactivated?

A

By cyclin D binding to CDK4

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10
Q

Define Hyperplasia

A

Increase in tissue or organ size due to increased cell numbers

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11
Q

What types of cell population can hyperplasia occur in?

A

Labile or Stable cells

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12
Q

Give 2 reasons why physiological hyperplasia occurs

A

1. Hormonal- to increase the functional capacity

2. Compensatory- increasing tissue mass after tissue damage

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13
Q

Why does pathological hyperplasia occur?

A

Secondary to excessive hormonal stimulation or growth factor production

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14
Q

Give 2 examples of physiological hyperplasia

A
  • Increased bone marrow production of erythrocytes in response to hypoxia
  • Proliferation of the endometrium under the influence of oestrogen
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15
Q

Give 2 examples of pathological hyperplasia

A
  • epidermal thickening in chronic eczema or psoriasis -
  • thyroid gland enlargement in response to iodine deficiency
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16
Q

Define hypertrophy

A

Increase in tissue or organ size due to an increased cell size

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17
Q

In what cell populations does hypertrophy occur?

A

All cell types but especially permanent cell types - in labile and stable tissues hypertrophy usually occurs alongside hyperplasia

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18
Q

Why does hypertrophy occur?

A

Increased functional demand or increased hormonal stimulation

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19
Q

Give 2 examples of physiological hypertrophy

A
  • skeletal muscle of a body builder
  • smooth muscle hypertrophy in the pregnant uterus
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20
Q

Give 3 examples of pathological hypertrophy

A
  1. left ventricular hypertrophy due to hypertension or calcified aortic valve
  2. smooth muscle hypertrophy in the bladder due to obstruction by an enlarged prostate gland
  3. smooth muscle hypertrophy in the intestine above an intestinal stenosis
21
Q

Give an example of compensatory hypertrophy

A

removal of one kidney causing the other to enlarge (combination of hypertrophy and hyperplasia)

22
Q

Define atrophy

A

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

23
Q

What is the difference between cellular atrophy and organ/tissue atrophy?

A

Cellular atrophy = decreased cell size to a size where survival is still possible

Organ/ tissue atrophy = decreased cell size AND apoptosis

24
Q

In organ atrophy, which cells are the first to undergo apoptosis?

A

Parenchymal cells apoptosis first, followed by stromal cells

Atrophic organs will therefore contain large amounts of connective tissue

25
Q

What is the best way to treat atrophy?

A

remove the cause

26
Q

Is atrophy reversible?

A

Yes, up to a point by will be less reversible after many years of parenchymal cells being replaced by connective tissue

27
Q

Give 2 examples of physiological atrophy

A
  • ovarian atrophy in post menopausal women
  • decrease in the size of the uterus after birth
28
Q

Give 8 examples of pathological atrophy

A
  1. atrophy of disuse e.g muscles after inactivity
  2. loss of nerve innervation
  3. inadequate blood supply (legs thin in peripheral vascular disease)
  4. inadequate nutrition
  5. loss of endocrine stimulus
  6. persistent injury e.g polymyositis (muscle inflammation)
  7. ageing e.g, senile atrophy of the brain or heart
  8. pressure e.g tissues around an enlarging tumour
29
Q

Define metaplasia

A

Reversible change of one differentiated cell type to another

30
Q

In what cell types can metaplasia occur?

A

Only in varieties of epithelia or connective tissue

31
Q

Can metaplasia occur across germ lines?

A

No

32
Q

What is the purpose of cells undergoing metaplasia?

A

To change to a cell type that is more suited to that altered environment

33
Q

Describe how cells in the bronchioles undergo metaplasia in response to cigarette smoke

A
  • Normal bronchial cells are pseudo stratified, ciliated, columnar cells
  • cigarette smoke causes metaplasia to simple, squamous epithelium
34
Q

What is Barret’s oesophagus?

A

When cells in the lower oesophagus change from stratified squamous epithelium to gastric/ intestinal type epithelium in response to acid reflux

35
Q

What is traumatic myositis ossificans?

A

When skeletal muscle fibroblasts change to osteoblasts causing metaplastic bone to develop in muscle -usually occurs after trauma when patient returns from injury before fully healed

36
Q

Define aplasia

A

The complete failure of a specific tissue or organ to develop

37
Q

Give an example of aplasia

A
  • Thymic aplasia - results in infections and auto-immune problems
  • Aplasia of the kidney
38
Q

Define hypoplasia

A

The congenital underdevelopment or incomplete development of a tissue/organ

39
Q

Give an example of hypoplasia

A
  • hypoplasia of heart chambers
  • renal hypoplasia
  • breast hypoplasia
  • testicular hypoplasia (seen in Klinefelter’s syndrome)
40
Q

Define atresia

A

congenital abnormality where no orifice forms e.g. anus or vagina

41
Q

Define reconstitution

A

Replacement of a lost part of the body e.g regrowth of antlers

42
Q

Define involution

A

Normal, programmed shrinkage of an organ

43
Q

Give examples of involution

A
  • Uterus shrinkage after childbirth
  • thymus in early life
44
Q

Define dysplasia

A

The abnormal maturation of cells within a tissue

45
Q

What happens to smooth muscle of a blocked duct?

A

Undergoes hypertrophy to try and eliminate blockage

46
Q

How do high doses of prednisone (glucocorticoids) affect adrenal glands?

A

Prednisone is used to treat asthma

In high doses is causes adrenal gland atrophy

47
Q

What is a side effect of tamoxifen? (Breast cancer adjuvant treatment)

A

Endometrial gland hyperplasia

48
Q

Name some of the causes of left ventricular hyperplasia

A
  • systemic hypertrophy
  • ischaemic heart disease
  • aortic stenosis/ regurgitation
  • mitral regurgitation
49
Q

Which cellular adaptations DO NOT predispose to neoplasia?

A
  • atrophy
  • hypertrophy

Path Processes (12 decks)

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