Flashcards in MOD S8 - Cellular Adaptations Deck (19)
List a and describe the phases of the cell cycle
What and when is R (the restriction point) in the cell cycle?
R is the most important checkpoint of the cell cycle where the cell decides whether to continue
It is at the end of G1
How is the cell cycle controlled?
By R (the restriction point) and the phosphorylation of the retinoblastoma protein (pRb)
When does the retinoblastoma protein become important?
pRb governs the cell cycles beyond R
Discuss the proliferative capacity of stem cell populations in labile tissue
Stem cells persistently divide to replenish losses
Discuss the proliferative capacity of stem cell populations in stable cell populations
Stem cells usually proliferate very slowly
Proliferate persistently when required
Discuss the proliferative capacity of stem cell populations in permanent cell populations
Stem cells present but cannot mount an effective proliferative response to significant cell loss
Replacement of cell losses by identical cells to maintain tissue or organ size
Increase in tissue or organ size due to an increase in cell numbers
Increase in tissue or organ size due to increase in cell size
Decrease in tissue or organ size due to decrease in cell number or size due to an acquired disease
Reversible change of one differentiated cell type to another
Complete failure of a specific organ or tissue to develop
Incomplete Development of a tissue or organ
Abnormal maturation of cells within a tissue
Where does hyperplasia occur? Give physiological and pathological examples and cell types.
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
Where does hypertrophy occur? Give physiological and pathological examples and cell types.
In permanent cell populations, occurs alone.
In more proliferative tissues, may occur with hyperplasia
Where does atrophy occur? Give physiological and pathological examples and cell types.
Can occur in many cell populations