Cellular Adaptations

Question 1

Define cellular adaptation

Answer 1

Cellular adaptation is a reversible change that allows cells to survive altered physiologic or pathologic conditions.

Question 2

Name the main types of cellular adaptations

Answer 2

Atrophy, hypertrophy, hyperplasia, metaplasia, and dysplasia are the main types

Question 3

Define atrophy

Answer 3

Atrophy is a decrease in cell size resulting in reduced organ size.

Question 4

List common causes of atrophy

Answer 4

Decreased workload, denervation, ischemia, malnutrition, and aging cause atrophy.

Question 5

What is the main mechanism of protein degradation in atrophy

Answer 5

The ubiquitin–proteasome pathway mediates protein degradation.

Question 6

What is autophagy

Answer 6

Autophagy is lysosomal digestion of cellular components during atrophy.

Question 7

What pigment accumulates in atrophic cells

Answer 7

Lipofuscin accumulates in atrophic cells.

Question 8

Define hypertrophy

Answer 8

Hypertrophy is an increase in cell size leading to organ enlargement.

Question 9

Why does hypertrophy occur instead of hyperplasia in muscle

Answer 9

Muscle cells cannot divide

Question 10

Give an example of physiologic hypertrophy

Answer 10

Skeletal muscle enlargement with exercise is physiologic hypertrophy.

Question 11

Give an example of pathologic hypertrophy

Answer 11

Left ventricular hypertrophy due to hypertension is pathologic hypertrophy.

Question 12

What stimulus initiates hypertrophy

Answer 12

Mechanical stress and growth factors initiate hypertrophy.

Question 13

Which pathway mediates physiologic hypertrophy

Answer 13

The PI3K–AKT pathway mediates physiologic hypertrophy.

Question 14

Why can prolonged hypertrophy become harmful

Answer 14

Sustained hypertrophy may lead to ischemia and organ failure.

Question 15

Define hyperplasia

Answer 15

Hyperplasia is an increase in the number of cells in a tissue.

Question 16

Where can hyperplasia occur

Answer 16

It occurs in tissues with dividing cells or stem cells.

Question 17

Give an example of hormonal hyperplasia

Answer 17

Endometrial hyperplasia due to estrogen excess is hormonal hyperplasia.

Question 18

Give an example of compensatory hyperplasia

Answer 18

Liver regeneration after partial hepatectomy is compensatory hyperplasia.

Question 19

What drives hyperplasia

Answer 19

Hyperplasia is driven by growth factor and hormone stimulation.

Question 20

Is hyperplasia reversible

Answer 20

Hyperplasia is reversible when the stimulus is removed.

Question 21

Define metaplasia

Answer 21

Metaplasia is replacement of one adult cell type by another.

Question 22

Why does metaplasia occur

Answer 22

It occurs to provide better protection against chronic stress.

Question 23

Give an example of squamous metaplasia

Answer 23

Smoking-induced bronchial squamous metaplasia is an example.

Question 24

What is intestinal metaplasia

Answer 24

Replacement of gastric epithelium by intestinal-type epithelium is intestinal metaplasia.

Question 25

What cells give rise to metaplasia

Answer 25

Stem cells or undifferentiated mesenchymal cells give rise to metaplasia.

Question 26

Is metaplasia reversible

Answer 26

Metaplasia is reversible if the stimulus is removed.

Question 27

Define dysplasia

Answer 27

Dysplasia is disordered epithelial growth with cytologic atypia.

Question 28

What features characterize dysplasia

Answer 28

Cellular pleomorphism, hyperchromasia, and loss of polarity characterize dysplasia.

Question 29

Where is dysplasia commonly seen

Answer 29

Dysplasia commonly occurs in cervix and respiratory epithelium.

Question 30

Why is dysplasia considered premalignant

Answer 30

Dysplasia can progress to carcinoma if persistent.

Question 31

What is carcinoma in situ

Answer 31

It is full-thickness epithelial dysplasia without invasion.

Question 32

Can dysplasia regress

Answer 32

Dysplasia may regress if the inciting cause is removed.

Question 33

What is the relationship between metaplasia and dysplasia

Answer 33

Chronic metaplasia may progress to dysplasia.

Question 34

Why are cellular adaptations clinically important

Answer 34

They explain organ changes and risk of progression to injury or cancer.

Question 35

What happens if adaptive limits are exceeded

Answer 35

Cells undergo injury