POM - MBC - Cell Injury and Fate

Question 1

How do normal cells become injured?

Answer 1

Cells need to adapt when under stress/when there is increased metabolic demand
If cells are unable to cope and reach their limit, they become injured or they die
Similarly, a healthy cell may be injured/die due to exposure to metabolic poisons or oxygen deprivation

Question 2

what are the 2 types of injury?

Answer 2

 Lethal - irreversible and leads to cell death

 Sub-lethal - produces injury NOT amounting to cell death. However, the injury may not be reversible and lead to cell death.

Question 3

What are the 8 causes of cell injury?

Answer 3

Oxygen deprivation, chemical agents, infectious agents, immunological reactions, genetic defects, nutritional imbalances, physical agents, ageing

Question 4

what is necroptotis?

Answer 4

• A programmed cell death associated with inflammation
• There are many causes (eg. Viral infections)

Question 5

what is the difference between apoptosis and necrosis?

Answer 5

• Apoptosis may be physiological
• Apoptosis is an active energy dependent process
• It is not associated with inflammation

Question 6

what are the causes of apoptosis?

Answer 6

• 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, causing irreparable DNA damage, triggering a suicide pathway

Question 7

what is the definition of apoptosis?

Answer 7

programmed cell death so the cell membrane stays inact, forming an apoptotic cell body

Question 8

what is the definition of necrosis?

Answer 8

confluent cell death associated with inflammation. there is damage of healthy tissues and an inflammatory response

Question 9

what are the 4 types of necrosis?

Answer 9

• coagulative
• liquefactive
  -caseous
• fat necrosis

Question 10

what is meant by reversible changes?

Answer 10

 Degenerative changes are changes associated with cell and tissue damage
 Examples include fatty change and cellular swelling
 These are cells that are unable to maintain normal

Question 11

what are the effects of the cell injury?

Answer 11

Effects of cell injury the structural and biochemical components of a cell are so integrally related that multiple secondary effects rapidly occur.

Cell function is lost BEFORE cell death occurs - so a ‘normal’ looking cell may not actually be functioning!

Question 12

what is the mechanism of cell injury?

Answer 12

The cellular response to injurious stimuli and the results (whether the injury is lethal or sub-lethal) depends on the type of injury, the duration (eg, how long cardiac myocytes are deprived of oxygen) and the severity.

The consequences of an injurious stimulus depends on the type of the cell affected (eg. Brain vs bone cells) and it’s status (whether it is in G0 or proliferating.

4 systems are vulnerable, they are the cell membrane, ATP generation, protein synthesis and the integrity of genetic apparatus (DNA)

Question 13

what are the 5 cellular adaptations to injury?

Answer 13

• atrophy
• hypertrophy
• hyperplasia
• metaplasia
• dysplasia

Question 14

what is atrophy and hypertrophy? give examples

Answer 14

atrophy - shrinkage in the size of the cell (or organ) by the loss of cell substance. There is atrophy of the brain in dementia, caused by atrophy of individual muscle cells following denervation

hypertrophy - increases in the size of the cell and consequently an increases in the size of the organ. Can be physiological or pathological. It is caused by either increased functional demand or specific hormonal stimulation. Physiological hypertrophy  the uterus during pregnancy

Question 15

what is hyperplasia, metaplasia and dysplasia?

Answer 15

hyperplasia - Increase in the number of cells in the organ which can be physiological (due to hormones or compensatory) or pathological hyperplasia, due to excessive hormonal or growth factor stimulation (proliferative endometrium vs. Carcinoma)

metaplasia - a reversible change in which one adult cell type is replaced by another. It may be physiological or pathological. Physiological (the cervix during pregnancy). Pathological (Barrett’s oesophagus or Columnar lined oesophagus. Due to acid reflux, the cells change from squamous to columnar lined cells)

dysplasia - the in-between of cancer cells (precancerous cells). Dysplasia is pre-cancerous cells which show the genetic and cytological features or malignancy but NOT INVADING THE UNDERLYING TISSUE. Often follows metaplasia