Flashcards in MoD Session 7- Cellular Adaptations Deck (62)
What is the size of cell populations dependent on?
The rate of:
What regulates normal cell proliferation?
What are the 4 outcomes for cells?
-differentiate (become specialised)
-divide (enter cell cycle)
-survive (resist apoptosis)
What are the three types of cell signalling?
What is autocrine signalling?
Where the cells respond to the signalling molecules that they themselves produce.
What is intracrine signalling?
Where the cell is affected by the signalling molecule that it produces, but this signal binds intracellularly and is never secreted.
What is paracrine signalling?
Where the signalling molecule produced by a cell acts on neighbouring cells.
What is endocrine signalling?
The cell secretes a hormone which travels in the blood stream to a distant target cell/ organ.
Cell to cell signalling can be via... (3)
-direct cell-cell or cell-stroma contact
What codes for growth factors?
What distance do growth hormones act over?
Apart from cell proliferation and inactivation, what else do growth hormones affect? (6)
With respect to the cell cycle, how does increased tissue growth occur? (2)
-shortening the cell cycle
-conversion of quiescent cells to proliferating cells by causing them to enter the cell cycle.
Which phase of the cell cycle is distinctive under the light microscope?
What does phase M include?
-mitosis (nuclear division)
-cytokinesis (cell division)
What is the rest of the cell cycle called?
What is cell progression controlled by and what do they do?
Checkpoints. They sense damage to DNA and ensure that damaged DNA does not replicate.
Wait is the most critical checkpoint and where is it found?
The restriction (R) checkpoint.
It is found at the end of G1.
What happens if checkpoint activation occurs?
The protein P53 comes into play and suspends the cell cycle and triggers DNA repair (if poss) or apoptosis.
Which protein and its associated enzyme control the cell cycle progression?
Cyclin-dependent kinases (CDKs)
What do activated CDKs do
Phosphorylate proteins so that they can move to the next stage of the cell cycle.
What is the activity of cyclin-CDK complexes regulated by?
What are labile cells and give 2 examples.
Ones that continue to multiply throughout life.
Bone marrow and epithelium.
What are stable cells and give 2 examples.
Stable cells are ones that both mature and stem cells can proliferate if needed, in regenerative bursts. They are usually quiescent.
Examples liver and kidney cells.
What are permanent cells and give 3 examples.
They are cells that are permanently differentiated and therefore cannot proliferate.
Examples are cardiac muscle, skeletal muscle and neural tissue
What are stem cells?
Cells with prolonged proliferation activity that show asymmetric replication.
What is asymmetric replication?
Where one daughter cell remains as a stem cell and the other goes on to differentiate into another cell type.
Are stem cells present in permanent cell populations?
Yes but they cannot amount an effective proliferative response to significant cell loss.