Pathology - Cellular Adaptations Flashcards
How is cell proliferation controlled?
- chemical signals from the microenvironment can simulate/inhibit cell proliferation
- signalling molecules bind to a receptor, causing modulation of gene expression
- receptors usually in cell membrane, but can be in cytoplasm/nucleus
How can a cell population be increased?
- shorten the cell cycle
- convert quiescent cells to proliferating cells by making them enter the cell cycle
How does the body determine whether a cell is able to replicate?
It has checkpoints in mitosis, where it checks that the DNA has replicated successfully and the cell is big enough
What is the restriction point?
Most critical checkpoint - the majority of cells which pass this will complete the cell cycle. Checkpoint activation delays cell cycle and triggers DNA repair mechanisms/apoptosis via p53
What are cyclins?
Cyclins and cyclin dependent kinases (CDKs) are active during different phases of the cell cycle. Cyclin activates CDK, which phosphorylates the target protein (which is bound to cyclin)
What is hyperplasia?
Increase in tissue or organ size due to increased cell numbers
What is hypertrophy?
Increase in tissue or organ size due to increased cell size
What is atrophy?
Shrinkage of a tissue or organ due to an acquired decrease in size and/or number of cells.
What is metaplasia?
Reversible change of one differentiated cell type to another
What types of tissue does hyperplasia occur in?
Labile/stable tissues
What causes hyperplasia?
- increased functional demand/hormonal stimulation
- can occur secondary to a pathological cause but proliferation is normal response
Is hyperplasia reversible?
Yah
In which types of tissue does hypertrophy occur?
Labile, stable but especially permanent
Does hypertrophy usually occur alone in tissue?
No, it usually occurs along with hyperplasia
Why don’t athletes get cardiac muscle hypertrophy despite their muscle being under more strain?
They have a rest between exercises, so the strain on their heart goes back to normal. Obese people cannot ‘rest’ their heart, so they always have stress on it