Session 7 & 8 Flashcards
What controls cell proliferation?
Hormones
Local mediators
Cell contact
What is Autocrine secretion?
The cell that secretes a signal is the responding cell.
What is Paracrine secretion?
The secreting cell and responding cell is different.
What produces epidermal growth factor?
Keratinocytes
Macrophages
Inflammatory cells
What does epidermal growth factors bind to?
Epidermal growth factor receptors.
What does vascular endothelial growth factors do?
It is an inducer of blood vessel development - vasculogenesis.
Role in formation of new blood vessels - angiogenesis.
Where is platelet derived growth factors stored?
In platelet alpha granules.
When is platelet derived growth factor released?
On platelet activation.
What does platelet derived growth factor cause?
Migration and proliferation of fibroblasts, smooth muscle cells and monocytes.
What are the outcomes of signalling?
Survive
Divide
Differentiate
Apoptosis
How can the growth of cells be increased?
By shortening the cell cycle.
By conversion of quiescent cells to proliferating cells by making them enter cell cycle.
What is the most important part of the cell cycle?
Extra point - Why?
G1.
Extra point - It has the R check point.
What is the most commonly altered position in the cell cycle during cancer?
The R checkpoint.
What happens if the R checkpoint is activated?
It delays the cell cycle
It triggers the DNA repair processes
It triggers apoptosis
What controls the cell cycle?
Proteins - cyclins
Associated enzymes - cyclin dependent kinases (CDKs)
How do CDKs drive the cell cycle?
They phosphorylate proteins that are critical for cell cycle transitions.
What stimulates the production of cyclins?
Growth factors.
What are the three types of cell ability to enter the cell cycle?
Labile - lots of stem cells
Stable - stem cells quiescent
Permanent - stem cels present. Cannot proliferate.
Give an example of labile, stable and permanent cells.
Labile - surface epithelia
Stable - hepatocytes
Permanent - cardiac muscle
What are the different cellular adaptions?
Regeneration Hyperplasia Hypertrophy Atrophy Metaplasia
Is cellular adaptions reversible or irreversible?
Reversible.
What is regeneration cellular adaption?
Replacement of cell losses by identical cells to maintain tissue or organ size.
Resolution and scarring when persistent.
What is hyperplasia cellular adaption?
Increase in tissue or organ size due to an increase in cell numbers.
Only occurs in labile or stable cell populations.
What is hypertrophy cellular adaption?
Increase in tissue or organ size due to an increase in cell size - have more intracellular components.
Occurs in permanent cells.
