Cellular adaptation to stress and toxic injury Flashcards

1
Q

What is hypoxia?

A

Insufficient oxygen levels in body tissues

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2
Q

What is ischaemia?

A

Reduced or restricted blood flow to part of body, which results in hypoxia of that area

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3
Q

How can ischaemia damage cells?

A

Less oxygen supplied to mitochondria, so less ATP is produced by oxidative phosphorylation, so cell has less energy

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4
Q

What 2 conditions can cause oxygen starvation of tissues?

A

Anaemia, carbon monoxide poisoning

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5
Q

How can anaemia cause oxygen starvation?

A

Low healthy RBC count, so less oxygen is carried to tissues

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6
Q

How can carbon monoxide poisoning cause oxygen starvation?

A

Carbon monoxide displaces oxygen bound to haemoglobin, as CO has a higher affinity for haemoglobin

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7
Q

Give 6 examples of physical agents that damage cells?

A

Radiation, electric shock, atmospheric pressure changes, temperature extremes, mechanical trauma

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8
Q

Give 3 examples of chemical agents that damage cells?

A

Alcohol, cyanide, arsenic

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9
Q

Give 4 examples of infectious agents that damage cells?

A

Viruses, parasites, bacteria, fungi

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10
Q

How can the immune system damage own cells?

A

Autoimmune diseases attack own cells

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11
Q

Give an example of how genetic abnormalities can damage cells?

A

Mutation of haemoglobin gene causes sickle cell anaemia

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12
Q

Give 3 examples of nutrition imbalance that damages cells?

A

Starvation, excess nutrition, vitamin deficiency

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13
Q

What is the general response of normal cells in a stressful environment?

A

Adapt to undergo reversible injury

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14
Q

What is cellular adaptation?

A

Reversible changes in size, number, phenotype, metabolic activity, function in response to changes in the environment

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15
Q

Give 4 methods of cellular adaptation?

A

Hypertrophy, hyperplasia, metaplasia, atrophy

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16
Q

What is hypertrophy?

A

Increase in the size of cells, resulting in increase in size of affected organ

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17
Q

How do hypertrophic cells increase their size?

A

Synthesise more intracellular structural components

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18
Q

Why do cells undergo hypertrophy?

A

They have limited ability to divide, so cannot respond by hyperplasia, as hyperplasia requires cell proliferation to increase organ size

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19
Q

When do muscle cells undergo hypertrophy?

A

Increased workload

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20
Q

What are the 2 types of hypertrophy?

A

Pathological, physiological

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21
Q

Give an example of physiological hypertrophy?

A

uterus size increases in response to pregnancy

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22
Q

Give an example of pathological hypertrophy?

A

Cardiac muscle size increases due to high bp created by damaged heart valves

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23
Q

What is hyperplasia?

A

Increase in number of cells by excessive cell division, in an organ/tissue in response to a stimulus

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24
Q

Give 2 types of stimuli that trigger hyperplasia?

A

Hormones, growth factors

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25
Q

What ability must cells have to undergo hyperplasia?

A

Ability to divide

26
Q

Why is hyperplasia a reversible change?

A

If stimulus is removed, hyperplasia will regress

27
Q

What are the 2 types of hyperplasia?

A

Pathological, physiological

28
Q

Give an example of physiological hyperplasia?

A

Breast glands undergo hyperplasia to increase milk production

29
Q

Why does pathological hyperplasia occur?

A

Inappropriate/excessive action of hormones/growth factors on target cells

30
Q

How do growth factors stimulate mature cells undergoing pathological hyperplasia?

A

Mature cells proliferate and stop if growth factors are removed

31
Q

How do growth factors stimulate stem cells?

A

Increase output of new cells

32
Q

Why does endometrial hyperplasia occur, and how does it present in a patient?

A

Prolonged stimulation of endometrium by oestrogen, presents as abnormal bleeding from uterus

33
Q

What is endometrial hyperplasia often a precursor of?

A

Endometrial cancer

34
Q

What hormone stimulates prostatic hyperplasia in men?

A

Androgen

35
Q

What other type of cellular adaptation can hyperplasia occur with?

A

Hypertrophy

36
Q

What is metaplasia?

A

Differentiated cell type is reprogrammed by stem cells into replacement cell type which is better suited to adverse environmental conditions

37
Q

What condition arises from prolonged metaplastic stimuli, and what type of tissue does it effect?

A

Dysplasia, which causes disordered growth in epithelium

38
Q

Is dysplasia reversible?

A

Potentially reversible if stimulus is removed in dysplasia early stages

39
Q

If dysplasia continues, what condition can develop?

A

Invasive carcinoma

40
Q

What chemical agent is the stimulus of squamous metaplasia in bronchioles?

A

Cigarette smoke

41
Q

What nutrition imbalance factor is a stimulus of squamous metaplasia in bronchioles?

A

Vitamin A deficiency

42
Q

How does cigarette smoke/Vitamin A deficiency stimulate metaplastic change in bronchioles?

A

Columnar cells of bronchiole lining are changed into metaplastic squamous cells

43
Q

What develops from metaplastic squamous epithelium lining bronchioles if the patient keeps smoking?

A

Disordered growth of metaplastic squamous epithelium develops into invasive squamous cell carcinoma

44
Q

What stimulates intestinal metaplasia in lower oesophagus?

A

Acid reflux from stomach

45
Q

What cells undergo metaplastic change in intestinal metaplasia of lower oesophagus?

A

Squamous epithelium lining changes into metaplastic goblet cells

46
Q

What develops from metaplasia of lower oesophagus if the patient keeps having acid reflux?

A

Invasive adenocarcinoma

47
Q

What is atrophy?

A

Reduction in size and number of cells which causes reduction of organ/tissue size

48
Q

How do cells decrease their size?

A

Organelles shrink in size

49
Q

What pathway is activated in atrophy?

A

Ubiquitin-proteasome pathway

50
Q

Where does ubiquitin attach to the target protein in the ubiquitin-proteasome pathway in atrophy?

A

Amino group of side chain of lysine residue

51
Q

When additional ubiquitins attach to the target protein in the ubiquitin-proteasome pathway, what chain is formed?

A

Multiubiquitin chain

52
Q

What is the name of a protein attached to a multiubiquitin chain?

A

Polyubiquitinated protein

53
Q

How does autophagy occur in the ubiquitin-proteasome pathway?

A

Proteasome recognises and degrades the polyubiquitinated protein, which is autophagy as the cell is digesting its own proteins

54
Q

What are the 2 types of atrophy?

A

Pathological, physiological

55
Q

How can bed rest cause disuse atrophy?

A

lack of movement causes skeletal muscle atrophy, which is a type of disuse atrophy

56
Q

What bone condition can disuse atrophy cause?

A

Osteoporosis

57
Q

How can denervation atrophy affect cell function?

A

Denervation atrophy damages nerve supply, which affects cell metabolism?

58
Q

How does chronic low blood supply cause pathological atrophy?

A

Organ compensates for low blood supply by decreasing cells so that they all have enough oxygen

59
Q

How can malnutrition cause skeletal muscle atrophy?

A

When fat is depleted, skeletal muscle is used as nutrition source instead, causes muscle wasting and cachexia (chronic weakening)

60
Q

Give an example of how loss of endocrine stimulation causes atrophy?

A

Lack of oestrogen causes atrophy of female genital tract and breast

61
Q

How can tumours cause pressure atrophy?

A

Tumour presses and constricts blood supply to tissues