17. Abnormalities of growth, differentiation and morphogenesis Flashcards Preview

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Flashcards in 17. Abnormalities of growth, differentiation and morphogenesis Deck (85):
1

What is a cellular adaptation?

Reversible changes in cellular size/number/phenotype/metabolic activity/function due to changes in environment or demand

2

During cellular adaptation, the cell may make changes in what?

- size
- number
- phenotype
- metabolic activity
- function

3

How is cellular adaptation different to cell injury and neoplasia?

Cell injury and neoplasia are irreversible whereas cellular adaptation is most often reversible

4

What is the role of cellular adaptation?

- acquire new, steady state of metabolism and structure
- better equips cell to survive in new environment

5

What may failure of adaptation lead to?

Sub-lethal or lethal cell injury

- marked susceptibility to injury
- stimulus is too severe

6

Tissues differ in their susceptibility to stress. Give examples

Cerebral neurons = very sensitive to hypoxia, rapidly die when subject to hypoxic stress

Fibroblasts = very resistant to damage, can survive for long periods in challenging environments

7

Depending on the cell population type, tissues either
- don't need to adapt
- adapt easily
- cannot adapt
Give an example of a tissue type that does not need to adapt

Fibroblasts

Survive severe metabolic stress without harm eg. absence of O2

8

Depending on the cell population type, tissues either
- don't need to adapt
- adapt easily
- cannot adapt
Give an example of a tissue type that can adapt easily

Epithelial cells

Labile cell population, active stem cell population, highly adaptive in number and function

9

Depending on the cell population type, tissues either
- don't need to adapt
- adapt easily
- cannot adapt
Give an example of a tissue type that cannot adapt

Cerebral neurons

Terminally differentiated, permanent cell population, highly specialised function, easily damaged by environmental change

10

What is PHYSIOLOGICAL cellular adaptation?

Responding to normal changes in physiology or demand

11

What is PATHOLOGICAL cellular adaptation?

Responding to disease related changes

12

What are 3 types of adaptive responses

- increased cellular activity
- decreased cellular activity
- changes in cell function and/or morphology

13

In what ways can a cell adapt to increase cellular activity?

Increase size and/or number of cells

14

In what ways can a cell adapt to decrease cellular activity?

Decreased size and/or number of cells

15

Increase in SIZE of cells is called what?

Hypertrophy

16

Increase in NUMER of cells is called what?

Hyperplasia

17

Hypertrophy and hyperplasia may co-exist. What do they both lead to?

Hypertrophy/hyperplasia = increased cell mass = increased capacity

18

Hypertrophy is an increase in size of existing cells and therefore an increase in functional capacity. What does this lead to?

- increased synthesis of structural components

- increased metabolism

19

In which tissues is hypertrophy particularly seen in?

Permanent cell populations, especially cardiac and skeletal muscle

20

Under what circumstances might a uterus be pathologically hypertrophied?

Adhered placenta causing post-partum haemorrhage

Causes uterus to be significantly larger after delivery

21

The prostate becomes enlarged as part of the ageing process, by a process of ....? hyperplasia

Adenomyomatous hyperplasia

22

When the prostate undergoes hyperplasia, what effect does this have on the bladder?

Detrusor muscle has to work harder during micturition - undergoes hyperplasia

23

Hyperplasia of the prostate can lead to further hyperplasia of the detrusor muscle of the bladder. What appearance does this give?

Trabeculated appearance

Can also get bladder diverticuli

24

Permanent cell populations can only respond to increased demand by doing what?

Increasing cell size

(hypertrophy)

25

How many cusps does the aortic valve have?

Give an abnormality

Normally has 3

Can get congenitally bicuspid aortic valve - often suffers from abnormal fibrosis and pathological calcification leading to inflexibility and narrowing of the orifice

26

What causes left ventricular failure?

Long standing systemic hypertension

Increased peripheral vascular resistance, increasing demand on left ventricle - hypertrophy will compensate for some time but if hypertension is left untreated, compensation may eventually fail

27

How might you diagnose left ventricular hypertrophy?

- clinical examination
- ECG
- imaging

28

Which valve abnormality would lead to left ventricular hypertrophy (LVH)?

Aortic stenosis

29

What can LVH predispose to?

- sudden degeneration of rhythm
- ventricular tachycardia
- ventricular fibrillation and sudden cardiac death

30

What is subcellular hypertrophy and hyperplasia?

Increase in size and number of subcellular organelles

31

Give an example of a subcellular hypertrophy and give the effect that this has

Smooth ER hypertrophy in hepatocytes with barbiturates, leading to an increase in P450 mixed function oxidases (the enzymes that live in the smooth ER) leading to an increased metabolism of other drugs

32

Smooth endoplasmic reticulum hypertrophy ultimately leads to what?

Increased metabolism of drugs

(due to increase in P450 mixed function oxidases)

33

Smooth endoplasmic reticulum hypertrophy is caused by which drug?

Barbiturates

34

What is hyperplasia?

Increase in number of cells caused by cell division

35

Which cell population types is hyperplasia possible in?

Labile and stable cell populations

36

Give 2 types of physiological hyperplasia

- hormonal
- compensatory

37

Give 2 types of pathological hyperplasia

- excess hormones
- growth factors

38

What is gynaecomastia?

Enlargement of the male breast due to hyperplasia of the glandular and stromal tissue in the breast

39

What may gynaecomastia be caused by?

- physioloigcal at puberty
- drugs (anabolic steroids, oestrogen)
- pathology eg. cirrhosis of liver

40

Why might you get hyperplasia of one kidney?

Due to hypoplasia of the other

41

What is the mechanism behind Grave's disease that causes hyperthyroidism?

An autoantibody binds to and switches on the TSH receptor in the thyroid, leading to prolonged, uncontrolled hyperplasia of the thyroid and hyperthyroidism (thyrotoxicosis)

42

What are the characteristic eye signs called in Grave's disease and what is this caused by?

Exophthalmos

Caused by abnormal deposition of ground substance in orbital tissues

43

What feature do you get in adenomyomatous hyperplasia of the prostate?

Hyperplastic nodules

(normal age-related change)

44

The abnormal healing process in a cirrhotic liver leads to the formation of what?

Hyperplastic nodules of hepatocytes

45

What is atrophy?

Reduction in size of organ or tissue by decrease in cell size and number

46

Give 2 examples of physiological atrophy?

- embryogenesis
- uterus after pregnancy or menopause

47

Pathological atrophy can be classified into which 2 categories?

- localised
- generalised

48

Which factors cause pathological atrophy?

- decreased workload
- loss of innervation
- diminished blood supply
- inadequate nutrition
- loss of endocrine stimulation
- pressure

49

When atrophy is caused by decreased workload, what is this called?

Disuse atrophy

50

When atrophy is caused by loss of innervation, what is this called?

Denervation atrophy

51

Give an example of atrophy caused by inadequate nutrition

Cachexia

52

Give an example of a situation which may cause disuse atrophy

Leg in cast

53

Give an example of an organ which may atrophy due to loss of endocrine stimulation

Uterus

54

Ageing and cerebrovascular disease has what effect on the brain?

Global atrophy

55

Give 2 examples of how atrophy of the kidneys may be caused

- renal artery stenosis (decreased blood supply)
- hydronephrosis (back pressure, from ureteric obstruction)

56

What is hydronephrosis?

A condition where the kidney becomes stretched or swollen as a result of a build up of urine inside them (eg. due to ureteric obstruction)

57

Which organ atrophies with age and is barely recognisable microscopically in the adult?

Thymus

(physiological atrophy)

58

What can pathologically cause atrophy of the adrenal cortex?

Steroid therapy - reduce the ACTH drive causing decrease in hormonal stimulation

59

What may patients be at risk of if long term steroids are stopped suddenly?

Addisonian crisis due to hypoadrenalism

Addisionian crisis = extremely low levels of cortisol (cortisol = important hormone produced by adrenal glands)

60

What are 2 mechanisms of atrophy?

- reduction in volume of individual cells
- death of individual cells (apoptosis)

61

What is involution?

Physiological atrophy caused by apoptosis

62

Reduction in volume of individual cells leads to formation of residual bodies. What can accumulation of residual bodies in cells be seen as?

Lipofuscin pigment

63

What does reduction in volume of individual cells lead to the formation of?

Residual bodies

64

Not all reduced cell mass is due to atrophy. What else can it be related to?

Developmental abnormalities

65

Give some conditions in the steps of development from embryonic cell mass to normal organ, which may cause reduced cell mass

- agenesis
- aplasia
- dysgenesis
- hypoplasia

66

What is metaplasia?

Transformation of one differentiated cell type into another

67

Which tissues can metaplasia affect?

Epithelium and mesenchymal tissues

Can also have transdifferentiation of stem cells

68

Why would cells undergo metaplasia?

Better adaptation to new environment

69

What pathological metaplasia does cigarette smoke cause?

Pseudostratified ciliated bronchial epithelium CHANGES TO squamous epithelium

70

What pathological metaplasia does bladder calculus/schistomosiasis/longstanding catheter cause?

Transitional epithelium of bladder CHANGES TO squamous epithelium

71

What pathological metaplasia does chronic trauma cause?

Fibrocollagenous tissue CHANGES TO bone

72

What pathological metaplasia does acid reflux cause?

Oesophageal squamous epithelium CHANGES TO columnar (glandular) epithelium

73

Why does smoking cause squamous metaplasia?

Squamous epithelium is better able to cope with noxious environment - squamous cell carcinomas

74

How are all these different types of adaptations linked to neoplasia?

Metaplasia/hyperplasia etc may form the basis on which neoplasia develops

75

Squamous metaplasia in cervix may lead to which neoplasia?

CIN and squamous cell carcinoma

76

Endometrial hyperplasia due to increased oestrogen may lead to which neoplasia?

Adenocarcinoma

77

Parathyroid hyperplasia due to chronic renal failure may lead to which neoplasia?

Adenoma

78

Squamous metaplasia in bronchus may lead to which neoplasia?

Dysplasia and squamous cell carcinoma

79

Squamous metaplasia in bladder may lead to which neoplasia?

Squamous cell carcinoma

80

Glandular metaplasia in oesophagus may lead to which neoplasia?

Adenocarcinoma

81

Which is dysplasia?

Earliest morphological manifestation of multistage process of neoplasia (hence irreversible)

82

Is dysplasia reversible or irreversible?

Irreversible

83

Dysplasia in an in-situ disease. What does this mean?

It is non-invasive. The abnormal cells have not yet acquired the capacity for invasion so they cannot spread

84

Carcinoma in-situ is another term for what?

Severe dysplasia

85

Dysplasia shows no invasion but does show what?

Cytological features of malignancy