Cellular Adaptations and Cell Death

Question 1

Describe cell types in terms of their proliferative capacity and give examples of each.

Answer 1

1. Permanent cells - non-proliferative. Neuron
2. Stable cells - usually non-proliferative. Hepatocyte
3. Labile cells - proliferative. Skin epidermis, intestinal tract

Question 2

What is hypertrophy?

Answer 2

An increase in individual cell size through the gain of cellular substance

Question 3

Why does hypertrophy occur?

Answer 3

As a result of increased functional demand or specific endocrine stimulation

Question 4

Give an example of physiological hypertrophy.

Answer 4

Enlargement of the uterus during pregnancy as a result of oestrogen-stimulated smooth muscle cell hypertrophy

Question 5

Give an example of pathological hypertrophy.

Answer 5

Enlargement of the heart as a result of hypertension

Question 6

What is hyperplasia?

Answer 6

An increase in cell number resulting from increased proliferation

Question 7

Give 2 types of physiological hyperplasia and an example of each.

Answer 7

1. Hormonal hyperplasia - glandular epithelium of breast in puberty and pregnancy
2. Compensatory hyperplasia - residual tissue grows after removal / loss of part of an organ

Question 8

Give an example of pathological hyperplasia.

Answer 8

Benign prostatic hyperplasia

Question 9

What is atrophy?

Answer 9

A decrease in cell size or number from loss of cellular substance

Question 10

List 4 causes of cell atrophy.

Answer 10

1. Decreased workload
2. Diminished blood supply
3. Loss of endocrine stimulation
4. Ageing

Question 11

What is metaplasia?

Answer 11

A change from one adult cell type to another adult cell type

Question 12

What is dysplasia?

Answer 12

The abnormal development of cells within a tissue or organ

Question 13

List 3 cellular features of dysplasia.

Answer 13

1. Nuclear enlargement
2. Loss of nuclear polarity
3. Increased cell division

Question 14

What are neoplasms?

Answer 14

Masses formed by the autonomous proliferation of cells that persists after cessation of the stimulus that provoked the change

Question 15

Describe the 4 key differences between benign and malignant neoplasms.

Answer 15

Benign - slow growing, remain localised, do not spread, margin does not infiltrate adjacent tissues

Malignant - fast growing, invasive, spread via metastasis, grow by destroying adjacent tissues and infiltrative margin

Question 16

List 5 histological features of neoplasms.

Answer 16

1. Loss of normal architecture
2. Loss of cell cohesion
3. Nuclear polymorphism
4. Nuclear enlargement
5. Increased mitotic activity

Question 17

List some causes of cell injury.

Answer 17

1. Physical agents
2. Infections
3. Immunological reactions
4. Hypoxia / ischaemia
5. Nutritional defects

Question 18

List 5 mechanisms of cellular injury.

Answer 18

1. Failure of membrane functional integrity
2. Blockage of metabolic pathways
3. Mechanical disruption
4. Energy failure
5. DNA damage or loss

Question 19

Why is ischaemia worse than hypoxia?

Answer 19

It results not only in reduced oxygen but also loss of nutrient delivery and build up of toxins

Question 20

What happens following ischaemia once blood flow is restored?

Answer 20

The renewed presence of oxygen results in a burst of mitochondrial activity that may result in the excessive release of reactive oxygen species, which are a type of free radical.

Question 21

Give an example of a direct acting toxin and how it causes damage.

Answer 21

Mercury - binds to proteins in the cell membrane, inhibits ATP-dependent transport, and increases membrane permeability

Question 22

Give an example of a latent toxin and how it causes damage.

Answer 22

Carbon tetrachloride - converted to a toxic free radical in the liver which causes damage to cell membranes

Question 23

What 4 things does necrosis involve?

Answer 23

1. Breakdown of plasma membrane, organelles; and nucleus
2. Large amorphous deposits of mitochondria
3. Leakage of contents
4. Inflammation (host reaction)

Question 24

Which type of necrosis is seen in TB infection?

Answer 24

Caseous necrosis

Question 25

Which type of necrosis is seen in infarcts?

Answer 25

Coagulative necrosis

Question 26

Mitochondria contain which protein that is capable of inducing apoptosis?

Answer 26

Cytochrome C

Question 27

Explain the chain of events that leads to cytochrome C causing apoptosis.

Answer 27

When the mitochondrial membrane becomes permeable, cytochrome c leaks into the cytoplasm and triggers caspase activation and apoptotic cell death.

Question 28

Which proteins initiate permeability of the mitochondrial membrane?

Answer 28

BAX and BAK

Question 29

In the death receptor pathway in cellular apoptosis, which ligand is bound?

Answer 29

Fas