Cell injury

Question 1

what is lethal cell injury?

Answer 1

produces cell death

Question 2

what is sublethal cell injury?

Answer 2

produces injury not amounting to cell death - may be reversible or may progress to cell death

Question 3

list the 8 causes of cell injury

Answer 3

1) Oxygen deprivation
2) Chemical agents
3) Infectious agents
4) Nutritional imbalances
5) Physical agents
6) Immunological reactions
7) Ageing
8) Genetic defects

oxygen came into nuts, particularly ice age generation

Question 4

what does the cellular response to injurious stimuli depend on?

Answer 4

• the type of injury
• the duration
• the severity

Question 5

what do the consequences of an injurious stimuli depend on?

Answer 5

• the type of cell
• the status of that cell
• its adaptability
• its genetic makeup

Question 6

what 4 intracellular systems are particularly vulnerable and often interlinked?

Answer 6

1) cell membrane integrity
2) ATP generation
3) protein synthesis
4) the integrity of the genetic apparatus (DNA and RNA)

Question 7

list the 6 cellular adaptations to injury

Answer 7

1) atrophy
2) hypertrophy
3) hyperplasia
4) metaplasia
5) dysplasia
6) apoptosis

Question 8

what is atrophy?

Answer 8

shrinkage in the size of the cell (or organ) by the loss of cell substance but the same number of cells are present

Question 9

give 2 examples of atrophy

Answer 9

• brain atrophy (dementia)

- muscle atrophy

Question 10

what is hypertrophy?

Answer 10

increase in the size of cells and consequently an increase in the size of the organ, caused by increased functional demand or specific hormone stimulation, which can be physiological or pathological

Question 11

give examples of physiological hypertrophy

Answer 11

• heart size increasing due to pregnancy
• heart size increasing in athletes
• hypertrophy of the uterus during pregancy

Question 12

give an example of pathological hypertrophy

Answer 12

• heart size increasing to due to raised BP

Question 13

what is hyperplasia?

Answer 13

an increase in the number of cells in an organ, which can be physiological or pathological

Question 14

what is physiological hyperplasia?

Answer 14

hormonal or compensatory

Question 15

what is pathological hyperplasia?

Answer 15

due to excessive hormonal stimulation or growth factor stimulation

Question 16

give an example of physiological hyperplasia

Answer 16

proliferative endometrium

Question 17

give an example of pathological hyperplasia

Answer 17

carcinoma

Question 18

what is metaplasia?

Answer 18

a reversible change in which one adult cell type is replaced by another, which can be either physiological or pathological

Question 19

give an example of physiological metaplasia

Answer 19

at puberty/during pregnancy the cervical canal opens up resulting in columnar cells becoming squamous for some time

Question 20

what is dysplasia?

Answer 20

precancerous cells which show the genetic and cytological features of malignancy due to increased mitosis, but not invading the underlying tissue

Question 21

what is attempted at the dysplasia stage?

Answer 21

screening to diagnose cancer at it leads to more successful treatment

Question 22

what are the light microscopic changes associated with reversible injury?

Answer 22

• fatty change: alcoholic fatty change due to excessive alcohol consumption, leading to liver disease
• cellular swelling: ballooning degeneration due to damage of the cell membrane

Question 23

what are the light microscopic changes associated with irreversible injury?

Answer 23

• coagulative necrosis: cells are dead but still visible (e.g. during MI)
• liquefactive necrosis: normal cell structure disappears (e.g. in cerebral infarction)
• caseous necrosis: “cheesy” necrosis resulting in normal cell structure disappearing but granular materials remaining (e.g. in pulmonary TB)
• fat necrosis: a result of inflammation of the pancreas - when the pancreas is damaged lipase is released

Question 24

what is necrosis?

Answer 24

confluent cell death (death of cells next to each other) associated with inflammation

Question 25

what is apoptosis?

Answer 25

programmed, single cell death with no inflammation, which is energy dependent and where cells are phagocytized by macrophages

Question 26

what are the causes of apoptosis?

Answer 26

- embryogenesis - deletion of auto-reactive T cells in the thymus - hormone-dependent physiological involution - cell deletion in proliferating populations - a variety of mild injurious stimuli that cause irreparable DNA damage that triggers cell suicide pathways

Question 27

list 3 differences between apoptosis and necrosis

Answer 27

1) apoptosis may be physiological, necrosis is not 2) apoptosis is an active energy dependent process, necrosis is not 3) apoptosis is not associated with inflammation, necrosis is

Question 28

what is necroptosis?

Answer 28

- energy dependent cell death - associated with inflammation unlike apoptosis - caused by viral infections