MOD S8 - Cellular Adaptations

Question 0

What and when is R (the restriction point) in the cell cycle?

Answer 0

R is the most important checkpoint of the cell cycle where the cell decides whether to continue
It is at the end of G1

Question 1

List a and describe the phases of the cell cycle

Answer 1

G1
S
G2
M

Question 2

How is the cell cycle controlled?

Answer 2

By R (the restriction point) and the phosphorylation of the retinoblastoma protein (pRb)

Question 3

When does the retinoblastoma protein become important?

Answer 3

pRb governs the cell cycles beyond R

Question 4

Discuss the proliferative capacity of stem cell populations in labile tissue

Answer 4

Stem cells persistently divide to replenish losses

Question 5

Discuss the proliferative capacity of stem cell populations in stable cell populations

Answer 5

Stem cells usually proliferate very slowly

Proliferate persistently when required

Question 6

Discuss the proliferative capacity of stem cell populations in permanent cell populations

Answer 6

Stem cells present but cannot mount an effective proliferative response to significant cell loss

Question 7

Define regeneration

Answer 7

Replacement of cell losses by identical cells to maintain tissue or organ size

Question 8

Define hyperplasia

Answer 8

Increase in tissue or organ size due to an increase in cell numbers

Question 9

Define hypertrophy

Answer 9

Increase in tissue or organ size due to increase in cell size

Question 10

Define atrophy

Answer 10

Decrease in tissue or organ size due to decrease in cell number or size due to an acquired disease

Question 11

Define metaplasia

Answer 11

Reversible change of one differentiated cell type to another

Question 12

Define aplasia

Answer 12

Complete failure of a specific organ or tissue to develop

Question 13

Define hypoplasia

Answer 13

Incomplete Development of a tissue or organ

Question 14

Define dysplasia

Answer 14

Abnormal maturation of cells within a tissue

Question 15

Where does hyperplasia occur? Give physiological and pathological examples and cell types.

Answer 15

In labile and stable cell populations
Physiologically occurs in bone marrow at high altitude and in the proliferative endometrium
Pathologically occurs in the thyroid goitre

Question 16

Where does hypertrophy occur? Give physiological and pathological examples and cell types.

Answer 16

In permanent cell populations, occurs alone.

In more proliferative tissues, may occur with hyperplasia

Question 17

Where does atrophy occur? Give physiological and pathological examples and cell types.

Answer 17

Can occur in many cell populations

Question 18

Where does metaplasia occur? Give physiological and pathological examples and cell types.

Answer 18

Most clearly adaptive in epithelial tissue
Occurs as a change in epithelium to one more suited to the new environment eg smokers’ pseudostratified ciliated changes to the more robust squamous
Can be a prelude to dysplasia/cancer