Cellular adaptatations

Question 1

What causes metaplasia?

Answer 1

Metaplasia is an adaptive response to physiological stimuli which cause stress to the cell, resulting in a change in cell type.

This can by physiological: e.g. change from glandular to squamous epithelium in the cervix, or pathological: squamous to glandular in Barrat’s oesophagus

The new cell type is better adapted to the stimulus.

Question 2

What causes atrophy?

Answer 2

Reduced workload
Loss of nerve supply
Reduced blood supply
Inadequate nutrition
Loss of endocrine stimulation
Ageing

Question 3

Give 3 exampls of labile cells

Answer 3

Squamous epithelium
Glandular epithelium
Bone marrow

Question 4

Give three examples of stable cells

Answer 4

Liver
Endocrine glands
Bone
Fibrous tissue

Question 5

Name 4 sites where stem cells can be found

Answer 5

Skin: basal cells
GI tract: crypts of Leiberukuhn
Lung: type 2 pneumocytes
Blood: HSCs
Liver: terminal bile ducts
Cornea: limbal arcade

Question 6

What are the four adaptive responses of cells?

Answer 6

Hypertrophy: increase in cell size
Hyperplasia: increase in cell number
Atrophy: reduction in cell size (involves autophagy)
Involution: reduction in cell number
Metaplasia: change in cell type

Question 7

What causes hyperplasia?

Answer 7

Response to hormones (growth factors) or chronic irritation

Question 8

What causes hypertrophy?

Answer 8

Increased functional demand, or response to hormones