Cellular adaptation to stress and toxic injury

Question 1

What is hypoxia?

Answer 1

Insufficient oxygen levels in body tissues

Question 2

What is ischaemia?

Answer 2

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

Question 3

How can ischaemia damage cells?

Answer 3

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

Question 4

What 2 conditions can cause oxygen starvation of tissues?

Answer 4

Anaemia, carbon monoxide poisoning

Question 5

How can anaemia cause oxygen starvation?

Answer 5

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

Question 6

How can carbon monoxide poisoning cause oxygen starvation?

Answer 6

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

Question 7

Give 6 examples of physical agents that damage cells?

Answer 7

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

Question 8

Give 3 examples of chemical agents that damage cells?

Answer 8

Alcohol, cyanide, arsenic

Question 9

Give 4 examples of infectious agents that damage cells?

Answer 9

Viruses, parasites, bacteria, fungi

Question 10

How can the immune system damage own cells?

Answer 10

Autoimmune diseases attack own cells

Question 11

Give an example of how genetic abnormalities can damage cells?

Answer 11

Mutation of haemoglobin gene causes sickle cell anaemia

Question 12

Give 3 examples of nutrition imbalance that damages cells?

Answer 12

Starvation, excess nutrition, vitamin deficiency

Question 13

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

Answer 13

Adapt to undergo reversible injury

Question 14

What is cellular adaptation?

Answer 14

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

Question 15

Give 4 methods of cellular adaptation?

Answer 15

Hypertrophy, hyperplasia, metaplasia, atrophy

Question 16

What is hypertrophy?

Answer 16

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

Question 17

How do hypertrophic cells increase their size?

Answer 17

Synthesise more intracellular structural components

Question 18

Why do cells undergo hypertrophy?

Answer 18

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

Question 19

When do muscle cells undergo hypertrophy?

Answer 19

Increased workload

Question 20

What are the 2 types of hypertrophy?

Answer 20

Pathological, physiological

Question 21

Give an example of physiological hypertrophy?

Answer 21

uterus size increases in response to pregnancy

Question 22

Give an example of pathological hypertrophy?

Answer 22

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

Question 23

What is hyperplasia?

Answer 23

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

Question 24

Give 2 types of stimuli that trigger hyperplasia?

Answer 24

Hormones, growth factors

Question 25

What ability must cells have to undergo hyperplasia?

Answer 25

Ability to divide

Question 26

Why is hyperplasia a reversible change?

Answer 26

If stimulus is removed, hyperplasia will regress

Question 27

What are the 2 types of hyperplasia?

Answer 27

Pathological, physiological

Question 28

Give an example of physiological hyperplasia?

Answer 28

Breast glands undergo hyperplasia to increase milk production

Question 29

Why does pathological hyperplasia occur?

Answer 29

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

Question 30

How do growth factors stimulate mature cells undergoing pathological hyperplasia?

Answer 30

Mature cells proliferate and stop if growth factors are removed

Question 31

How do growth factors stimulate stem cells?

Answer 31

Increase output of new cells

Question 32

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

Answer 32

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

Question 33

What is endometrial hyperplasia often a precursor of?

Answer 33

Endometrial cancer

Question 34

What hormone stimulates prostatic hyperplasia in men?

Answer 34

Androgen

Question 35

What other type of cellular adaptation can hyperplasia occur with?

Answer 35

Hypertrophy

Question 36

What is metaplasia?

Answer 36

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

Question 37

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

Answer 37

Dysplasia, which causes disordered growth in epithelium

Question 38

Is dysplasia reversible?

Answer 38

Potentially reversible if stimulus is removed in dysplasia early stages

Question 39

If dysplasia continues, what condition can develop?

Answer 39

Invasive carcinoma

Question 40

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

Answer 40

Cigarette smoke

Question 41

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

Answer 41

Vitamin A deficiency

Question 42

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

Answer 42

Columnar cells of bronchiole lining are changed into metaplastic squamous cells

Question 43

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

Answer 43

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

Question 44

What stimulates intestinal metaplasia in lower oesophagus?

Answer 44

Acid reflux from stomach

Question 45

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

Answer 45

Squamous epithelium lining changes into metaplastic goblet cells

Question 46

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

Answer 46

Invasive adenocarcinoma

Question 47

What is atrophy?

Answer 47

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

Question 48

How do cells decrease their size?

Answer 48

Organelles shrink in size

Question 49

What pathway is activated in atrophy?

Answer 49

Ubiquitin-proteasome pathway

Question 50

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

Answer 50

Amino group of side chain of lysine residue

Question 51

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

Answer 51

Multiubiquitin chain

Question 52

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

Answer 52

Polyubiquitinated protein

Question 53

How does autophagy occur in the ubiquitin-proteasome pathway?

Answer 53

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

Question 54

What are the 2 types of atrophy?

Answer 54

Pathological, physiological

Question 55

How can bed rest cause disuse atrophy?

Answer 55

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

Question 56

What bone condition can disuse atrophy cause?

Answer 56

Osteoporosis

Question 57

How can denervation atrophy affect cell function?

Answer 57

Denervation atrophy damages nerve supply, which affects cell metabolism?

Question 58

How does chronic low blood supply cause pathological atrophy?

Answer 58

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

Question 59

How can malnutrition cause skeletal muscle atrophy?

Answer 59

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

Question 60

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

Answer 60

Lack of oestrogen causes atrophy of female genital tract and breast

Question 61

How can tumours cause pressure atrophy?

Answer 61

Tumour presses and constricts blood supply to tissues