MoD Session 7 Flashcards Preview

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Flashcards in MoD Session 7 Deck (122):
0

What does the size of a cell population depend on?

Proliferation
Cell death

1

What regulates proliferation in physiological and pathological conditions?

Proto-oncogenes

2

How are cells stimulated to divide?

Signal molecule binds to a receptor modulating gene expression and causing the cell to enter the cell cycle

3

How can increased cell growth arise?

Shortening of cell cycle
Conversion of quiescent cells

4

Where can receptors for signal molecules modulating gene expression be found in a cell?

Usually membrane but can be cytosol or nucleus

5

How can cell to cell signalling occur to cause cells to divide?

Hormones
Local mediators
Direct cell-cell/cell-stroma contact

6

How does endocrine signalling take place?

Cell secretes molecules into circulation which then act on a distant cell

7

How does autocrine signalling work?

Cell secretes molecules and expresses receptors for them on CSM

8

How does intracrine cell signalling work?

Cell synthesises signalling molecules but does not secrete it so it can act on receptors present in the cell

9

How does paracrine cell singling work?

Cell releases molecules that act on a nearby cell

10

What is G1?

Gap 1 stage in the cell cycle before DNA synthesis where the cell grows

11

What happens in the S stage of the cell cycle?

DNA synthesis

12

What is G2?

Gap 2 stage of the cell cycle where the cell prepares to divide

13

What happens in the M stage of the cell cycle?

Mitosis

14

Where are the checkpoints in the cell cycle located?

Between G1 and S
Between G2 and M

15

What distinctive processes occur during the M stage of the cell cycle that can be seen under the light microscope?

Mitosis
Cytokinesis

16

What regulates transition of a cell from G1 to S in the cell cycle?

Cyclin E
CDK2

17

What regulates transition of a cell from S to G2 in the cell cycle?

Cyclin A
CDK2

18

What regulates transition of a cell from G2 to M in the cell cycle?

Cyclin B
CDK1

19

What regulates transition of a cell from M to G1 in the cell cycle?

Cyclin D
CDK2

20

What is permanent exit from the cell cycle called?

Terminal differentiation

21

How long does it take for a cell to enter the cell cycle

A few hours

22

During which stages of the cell cycle does interphase occur?

G1
S
G2

23

Which is the most critical point in control of the cell cycle?

Restriction point towards the end of G1

24

What happens to the majority of cells that pass the restriction point?

Complete the full cell cycle

25

What can the restriction point towards the end of G1 also be considered as?

Point of no return

26

What is the most commonly altered checkpoint in cancer cells?

Restriction point

27

What can checkpoint activation trigger?

DNA repair
Apoptosis via p53

28

What action does p53 have when a checkpoint is activated?

Stops cell cycle and stimulates DNA repair which if not possible will then stimulate apoptosis

29

What are cells responsive to up until the restriction point?

Mitogenic growth factors
TGF-beta

30

How do cyclins tightly regulate the transition of cells from G to S?

Bind with enzymes needed causing phosphorylation of the substrate activating the cyclin dependent kinase

31

What tightly regulates the CDK-cyclin complex?

CDK inhibitors

32

What are growth factors?

Polypeptides that act on specific CSM receptors to regulate transcription of genes regulating entry and passage of the cell through the cell cycle

33

What effects do growth factors have on a cell?

Proliferation
Inhibition
Locomotion
Contractility
Differentiation
Viability
Activation
Angiogenesis

34

Give four named examples of growth factors.

Epidermal growth factor
Vascular endothelial growth factor
Platelet derived growth factor
Granulocyte colony-stimulating factor

35

Why is GCSF given after chemotherapy?

Used pharmacologically to stimulate neutrophil release from bone marrow

36

What is the difference between adult and embryonic stem cells?

Adult have one mature type
Embryonic have multiple mature types

37

What replenishes loss of differentiated cells?

Tissue stem cells present in most but not all adult tissues

38

Compare the proliferation of labile, stable and permanent stem cells.

Labile: divide persistently to replenish losses
Stable: normally quiescent/slowly proliferating but proliferate persistently when needed
Permanent: cannot mount an effective proliferative response to significant cell loss

39

How long do labile mature cells live?

Short amount of time

40

Can stable mature cells proliferate if needed?

Yes

41

Can cell adaptation be reversed?

Yep as long as cell isn't injured

42

What is regeneration?

Replacement of cell losses by identical cells to maintain tissue/organ size

43

How does the effectiveness of cells after regeneration change?

After a short delay they are as effective as the original cells

44

Why are immature respiratory epithelial cells immune to flu virus?

Lack receptors as not fully functional yet

45

What happens in regeneration if a harmful agent persists?

Causes extensive damage including to permanent cells leading to scar formation

46

What happens in regeneration if a harmful agent is removed?

Tissue damage is limited so regeneration can occur in non-permanent tissue causing a negligible scar which does not affect function therefore achieving resolution

47

What is the Hayflick number?

Number of regenerations cells can undergo dependent on species and its life expectancy

48

What is hyperplasia biologically similar to?

Regeneration

49

What is characteristic about the increase in size seen in hyperplasia?

It is not uniform

50

When can hyperplasia occur?

Only in labile or stable cell populations under reversible physiological control

51

What can hyperplasia be in response to?

Normal response to abnormal condition
Secondary response to pathological cause

52

What does hyperplasia expose a cell to?

Risk of mutations - neoplasia

53

Why is hyperplasia seen physiologically in the endometrium and bone marrow?

To increase functionality of the tissue

54

What stimulates physiological hyperplasia?

Hormones

55

Give two examples of pathological hyperplasia.

Eczema
Goitre

56

What is hyperplasia?

Increase in tissue/organ size due to increased cell number

57

What is hypertrophy?

Increase in tissue/organ size due to increase in cell size

58

What causes hypertrophy in permanent cells?

Increased workload by increased functional demand or hormonal stimulation

59

Why do hypertrophied cells contain more structural components?

So workload is shared and therefore less likely to injure individual components

60

What can hypertrophy occur alongside?

Hyperplasia

61

In what tissues is physiological hypertrophy seen?

Skeletal muscle
Pregnant uterus

62

In what tissues can pathological hypertrophy be seen?

Ventricular muscle
Bladder muscle due to compression by prostrate

63

What is atrophy?

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

64

How does the reversibility of atrophy change with time?

Possible but becomes less so with increased time

65

How are residual bodies formed in atrophy?

Cells get rid of what they can manage without

66

In what order are tissues lost in atrophy?

Functional tissues are lost before connective tissue support

67

In what order does pancreatic tissue atrophy?

Leaves islets of Langerhans in islands of CT as parenchyma lost before stroma

68

What is metaplasia?

Reversible change of one differentiated cell type to another

69

Is atrophy associated more with physiology or pathology?

Pathology

70

What do many metaplasias represent?

Adaptive substitution

71

What allows metaplasia to happen?

Altered stem cell differentiation

72

How does metaplastic tissue differ from dysplastic and cancerous epithelium?

It is fully differentiated so is organised

73

What can metaplasia sometimes prelude?

Dysplastia and cancer

74

What cells can metaplasia happen in?

Only in cells that replicate

75

What causes the new phenotype in metaplasia?

New genetic programme expression

76

What is reconstitution?

Replacement of a lost part of the body

77

How does reconstitution differ from proliferation?

Requires coordination of lots of different cell types not just one

78

When is reconstitution seen in adults?

Angiogenesis

79

Shay are scars hairless?

Hair follicles cannot reconstitute

80

Why is physiological hypertrophy of cardiac muscle not dangerous?

There is a period of rest from the increased resistance to blood flow causing the hypertrophy

81

When does physiological hypertrophy of the heart become pathological?

If the increased angiogenesis for the heart is insufficient and causes relative ischaemia

82

What is compensatory hypertrophy?

Removal of one of a paired organ causes functional overstrain on the remaining organ thus causing hypertrophy

83

What is seen in functional overstrain of the kidney?

Hypertrophy
Hyperplasia

84

What happens if the functional overstrain is removed in compensatory hypertrophy?

Hypertrophy is resolved

85

What can cause pathological atrophy?

Loss of endocrine stimuli
Inadequate nutrition
Senile atrophy
Inadequate blood supply
Denervation
Persistent injury
Pressure
Disuse

86

In what organs is senile atrophy seen in?

Spleen
Liver
Heart
Brain
Kidneys

87

Why does only partial or gradual inadequate blood supply cause pathological atrophy?

Sudden inadequate blood supply causes cell injury

88

In what circumstances is physiological atrophy seen?

Post menopausal ovaries
Post childbirth

89

What causes physiological atrophy?

Loss of endocrine stimuli

90

Which disease is an example of cerebral pathological atrophy?

Alzheimer's

91

How can atrophy of disuse be reversed?

With activity

92

Why does smoking cause metaplasia?

The end tissue is better able to withstand the irritating effects of smoke

93

What change in phenotype is seen in metaplasia caused by cigarette smoking?

Bronchial pseudostratified ciliated epithelium to stratified squamous epithelium

94

What is lost in metaplasia caused by cigarette smoke?

Mucociliratory escalator

95

What metaplasia is seen in persistent acid reflux?

Stratified squamous to gastric/intestinal glandular epithelium

96

What is metaplasia due to persistent acid reflux called?

Barrett's oesophagus

97

How does muscle injury lead to metaplasia?

Fibroblasts turn into osteoblasts so bone is laid down in muscle

98

What causes metaplasia in muscle injury?

Returning to activity prematurely after injury

99

What is hypoplasia?

Congenital condition in which there is an underdevelopment/incomplete development of a tissue/organ at the embryonic stage due to an inadequate number of cells

100

Where might hypoplasia be seen?

Kidneys
Breasts
Testes in Klinefelter's syndrome
Chambers of the heart

101

Who discovered the function of platelets, described helicon acted pylori and classified cells by stheir ability to multiply?

Giulio Bizzozero

102

What is aplasia?

Embryonic developmental disorder causing complete failure of a specific tissue/organ to develop

103

What does thymic aplasia cause?

Infections and autoimmune problems

104

What is seen in aplasia of a kidney?

Only one kidney present

105

What term is used to describe an organ whose cells no longer proliferate?

Aplasia

106

What is seen in aplastic anaemia?

Aplasia of bone marrow

107

What is involution?

Normal programmed shrinkage of an organ

108

When is involution seen?

Uterus after childbirth
Thymus in early life
Foetal organs (pro- and mesonephros)

109

What is atresia?

Lack of an opening which can be seen in part of the gut/anus/vagina

110

What is dysplasia?

Potentially reversible abnormal cells in a tissue

111

What is dysplasia often seen before?

Cancer

112

Why is the regenerative capacity of a tendon poor?

It is avascular

113

Why is secondary rupture of a tendon common?

Due to abnormal use of other tendons to compensate

114

What is the regenerative capacity of the skin?

Good

115

What is the regenerative capacity of the liver?

Good

116

What happens to transplant livers which demonstrates its good regenerative capacity?

It will regrow to almost the exact same size of the removed liver

117

In what circumstances is peripheral nerve regeneration capacity not OK?

If injury is severe
If distance to be branched is too far

118

Why is hypopigmentation seen in scars?

Poor regenerative capacity of melanocytes

119

What causes a neuroma?

Disorganised regeneration of a peripheral nerve

120

What does the CNS have instead of good regenerative capacity?

Plasticity to form alternative pathways around damage

121

Why is improvement in symptoms seen following strokes with therapy?

CNS forms alternative pathways around the damage