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Y2 MECHANISMS OF DISEASE > Abnormal Growth, Differentiation & Morphogenesis > Flashcards

Abnormal Growth, Differentiation & Morphogenesis Flashcards

1
Q

What is meant by cellular adaptations?

Why do they need to occur?

A

cellular changes in response to changes in environment or demand

they need to occur as a normal cell in its resting state is confined to limited function and structure

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2
Q

What is meant by cellular adaptations being reversible?

A

when there is a change in demand, the cell adapts and reaches a new steady state of normal

the cell can recover and return to its original state without any harmful consequences

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3
Q

What are the 5 ways in which cells tend to adapt?

A
  1. size
  2. number
  3. phenotype
  4. metabolic activity
  5. function
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4
Q

Why do cells adapt?

A

they need to acquire a new, steady state of metabolism and structure

this better equips cells to survive in a new environment

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5
Q

What happens if cells fail to adapt?

A

failure of adaptation may lead to sub-lethal or lethal cell injury

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6
Q

What determines a cell’s susceptibility to environmental change?

A

whether or not it is able to adapt

some cells don’t need to adapt

some adapt easily

some cannot adapt at all

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7
Q

What is an example of a cell that doesn’t need to adapt?

Why?

A

fibroblasts

they can survive metabolic stress without harm

e.g. absence of oxygen

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8
Q

What is an example of a group of cells that can adapt easily?

How do they tend to adapt and how are they able to do this?

A

epithelial cells

they are a labile cell population with an active stem cell compartment

they are highly adaptive in number and function

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9
Q

What is meant by labile cells?

A

labile cells are cells that multiply constantly throughout life

they have a high turnover

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10
Q

What is an example of a cell that cannot adapt?

Why can it not adapt and what does this mean for the cell?

A

cerebral neurones

they are terminally differentiated and a permanent cell population

they have a highly specialised function and are easily damaged

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11
Q

What are the 2 types of stimuli that lead to cellular adaptation?

A
  1. physiological stimuli
  2. pathological stimuli

they are not always mutually exclusive - a physiological stimulus can become pathological if it persists for too long

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12
Q

What is an adaptation to a physiological stimulus?

A

responding to normal changes in physiology or demand

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13
Q

What is an adaptation to a pathological stimulus?

A

responding to disease related changes

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14
Q

What are the 3 types of adaptive response?

A
  1. increased cellular activity
  2. decreased cellular activity
  3. change of cell function and/or morphology (type of cells that are there in the first place)
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15
Q

How is an increase or decrease in cellular activity acheived?

A

through an increased or decreased size or number of cells

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16
Q

What is the difference between hypertrophy and hyperplasia?

A

hypertrophy:

increase in SIZE of cells

hyperplasia:

increase in NUMBER if cells due to excessive cell division

they both lead to an increased cell mass

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17
Q

How does hypertrophy affect cells, their functional capacity and their metabolism?

A

there is an increase in size of existing cells and an increase in functional capacity

there is increased metabolism and increased synthesis of structural components

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18
Q

What type of cell populations does hypertrophy tend to be seen in?

A

permanent cell populations

particularly cardiac and skeletal muscle

these are cells that don’t divide very well

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19
Q

What is the stimulus that leads to hypertrophy in the heart?

A

chronic haemodynamic overload e.g. due to high blood pressure

this increases the demand of the heart, leading to an increase in size of the muscles

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20
Q

What is an example of physiological hypertrophy?

A

during pregnancy, the uterus becomes hypertrophied to meet the demands of the growing foetus

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21
Q

What is shown by the different coloured arrows?

A

green - uterus in an elderly woman

yellow - normal healthy uterus

red - uterus in pregnancy

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22
Q

What changes are seen in the uterus in pregnancy (bottom picture)?

A

there are fewer cells which are larger

there are spaces between the cells due to oedema (fluid) between the cells

you can clearly see individual cells

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23
Q

What can benign hyperplasia of the prostate gland lead to?

A

trabeculated hypertrophied urinary bladder

this is because the bladder has to work harder to push urine through the urethra, so it becomes hypertrophied

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24
Q

What is the difference in the skeletal muscle shown?

A

left - normal 50 year old man

right - veteran marathon runner with hypertrophied skeletal muscle due to increased demands of the cells

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25
Q

What defect/condition is seen in this aortic valve?

A

it has 2 cusps instead of 3

a congenitally bicuspid aortic valve is more prone to calcification, which makes the valve stiff

this is aortic stenosis

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26
Q

How can aortic stenosis affect the ventricles of the heart?

A

a stiff calcified valve means the myocardium has to work harder to open the valve

this leads to left ventricular hypertrophy

27
Q

What condition is shown in this image?

A

the bottom image shows left ventricular hypertrophy

the cardiac myocytes cannot increase in number by dividing so have increased in size

28
Q

Other than aortic stenosis, what are other causes of LVH?

A

1, hypertension increases peripheral resistance so the heart has to work harder to pass blood around the body

  1. mitral and aortic regurgitation
  2. hypertrophic cardiomyopathy
29
Q

What are the symptoms of LVH?

A

there are no symptoms for a long time and then:

  1. breathlessness
  2. decrease in exertion levels
  3. tired when walking up stairs
  4. palpitations
  5. dizziness and fainting
30
Q

How is LVH diagnosed?

A
  1. clinical examination
  2. ECG or echocardiogram
  3. other imaging of the heart
31
Q

What are the problems associated with LVH, relating to blood supply?

A

hypertrophied muscle needs an increased blood supply, but the blood supply has not changed

this leads to problems with ischaemia, risk of MI

32
Q

How can LVH lead to an increased risk of stroke?

A

the myocardium becomes dilated

aneurysm formation can lead to clots and thrombuses forming in the dilated myocardium

33
Q

What is meant by subcellular hypertrophy and hyperplasia?

A

an increase in size and number of subcellular organelles

34
Q

How can barbiturates lead to subcellular hypertrophy and hyperplasia?

What is the main problem with this?

A

barbiturates cause hypertrophy of smooth endoplasmic reticulum in hepatocytes

this increases the amount of P450 mixed function oxidases

increasing ER leads to an increased metabolism of other drugs

35
Q

What is hyperplasia?

In which cell populations can it occur?

A

an increase in number of cells caused by cell division

this is possible in labile and stable cell populations

36
Q
A
37
Q

What are the 2 types of physiological hyperplasia?

A

hormonal:
increase in the capacity of an organ to perform its function

compensatory:

an increase in cell number needed due to injury

38
Q

What are the outcomes of pathological hyperplasia?

A

It can be hormonal or growth factor driven

it leads to either:

  1. proliferation of mature cells
  2. increased output of new cells
39
Q

What is shown in this image?

A

hyperplasia of breast tissue

this can occur physiologically or pathologically in response to certain drugs

40
Q

How is Graves disease an example of hyperplasia?

A
  1. autoantibody to TSH receptor leads to constant stimulation of the thyroid gland
  2. thyroid gland becomes hyperplastic to meet demand
  3. there is constant production of T3 and T4 leading to patient becoming hot, sweaty, lose weight and have palpitations
41
Q

How can the liver undergo both physiological and pathological hyperplasia?

A

physiological:

when parts of the liver are removed from a living donor, the liver can divide and regenerate

pathological:

when the liver regenerates after damage, it leads to nodules of regenerating tissue surrounded by areas of fibrosis

42
Q

What is meant by atrophy?

A

reduction in size of organ or tissue by decrease in cell size and normal

43
Q

What are examples of physiological atrophy?

A
  1. the uterus atrophies after pregnancy or menopause
  2. during embryogenesis many structures will atrophy and disappear
44
Q

What are the 2 types of pathological atrophy?

A
  1. localised
  2. generalised
45
Q

What are the 6 types of pathological atrophy?

A
  1. disuse atrophy - due to decreased workload
  2. denervation atrophy - due to loss of innervation
  3. diminished blood supply
  4. inadequate nutrition
  5. loss of endocrine stimulation
  6. pressure
46
Q

What is an example of pressure atrophy?

A

if a tumour is compressing another organ, this may lead the other organ to become atrophic

47
Q

What are the 2 types of atrophy which may occur in the thyroid gland?

A

physiological:

there is natural atrophy in the thymus from childhood to adulthood

pathological:

steroid use reduces the release of ACTH causing the adrenal gland to shrink as it is not being used

48
Q

What are the 2 ways in which atrophy occurs?

How is this acheived?

A
  1. reduction in volume of individual cells
  2. death of individual cells

this is acheived through:

  1. decrease in normal protein synthesis of the cell
  2. increase in protein degradation
49
Q

What is meant by agenesis?

A

complete failure of an organ to develop at all

50
Q

What is meant by aplasia?

A

failure of an organ to attain size or function but there is some recognisable tissue present

51
Q

What is meant by dysgenesis?

A

abnormal organ development during embryonic growth

52
Q

What is meant by hypoplasia?

A

under-development or incomplete development of a tissue or organ

53
Q

What occurs if organ development fails at each of the following stages

A
54
Q

What is meant by metaplasia?

A

the transformation of one differentiated cell type into another

this is acheived by trans-differentiation of stem cells

it is REVERSIBLE

55
Q

Why does metaplasia occur?

Which tissues tend to be affected?

A

it occurs to allow cells to become better adapted to a new environment

it can affect epithelium and mesenchymal tissues

56
Q

What are the 2 types of cell in the cervix?

What cellular changes occur in the cervix during puberty?

A

Ectocervix is made from stratified squamous epithelium to withstand outside environment

Endocervix is made from columnar cells

During puberty, the endocervix moves down and becomes exposed

There is a change in cell type from columnar to stratified squamout

57
Q
A
58
Q

Which part of the cervix is more vulnerable to cancer and why?

A

transition zone

this is where the epithelium changes from columnar and stratfied squamous

this area of metaplasia is turning over more quickly and is more vulnerable to HPV infection

59
Q

Fill out the table

A
60
Q

What types of carcinomas can develop from the following metaplasias?

A
61
Q

What is dysplasia?

Why is it important to detect?

A

dysplasia is disordered growth that is IRREVERSIBLE

it is the earliest morphological manifestation of multistage process of neoplasia

it shows cytological features of malignancy, but no invasion

62
Q

What is meant by dysplasia being ‘in-situ’?

A

it is non-invasive

the cancer has not yet invaded through the basement membrane and spread

63
Q

Why is dyplasia important to detect?

A

it gives a chance to treat a potentially fatal tumour before it arises

the abnormal cells have not yet acquired the capacity for invasion so they cannot spread

64
Q

What are the stages in dysplasia leading to carcinoma?

A

Y2 MECHANISMS OF DISEASE (36 decks)

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