Cell signalling and regulation Flashcards
Why do cells communicate?
- To develop - know where to go, what to do, how big to grow.
- To function - cells work together in communities
- Sense and respond to the environment
What is the process of cell signalling?
Extracellular signal is detected by the receptor on a target cell. The single is then converted from one form to another, an intracellular signalling molecules causes molecular change, altering cell behaviour.
Endocrine signalling
Signalling molecule - Hormones (produced in endocrine organs)
Mode of transport - through the blood
Effects the whole body
AA derivatives and peptide hormones act via binding to receptors on plasma membrane
Steroid hormones act via intracellular receptors
Function - physiological and metabolic changes during development
Paracrine signalling
Signalling molecule - cytokines and growth factors
Mode of transport - diffusion through extracellular medium
Effects specific tissue and organs (local process)
Acts via receptors on plasma membrane
Function - development (growth factor), would healing (transformation growth factors), inflammation (interleukins). Occurs int he brain and skin (in response to injuries)
Neuronal signalling
Signalling molecule - electrical signals and chemical signals
Mode of transport - over long distances via axons
Effects over long distances
Quick and specific effect
What is lidocaine and why is it administered with adrenaline?
Interfering with neuronal signals can have clinical benefits (for example pain killers - blocking pain receptors)
Lidocaine is a painkiller and is administered with adrenaline (constricts the blood vessels) so the affects last longer.
Contact-dependent signalling
Signalling molecules - membrane or matrix bound molecules of touching cells
Important in the development and immune response. It can cause lateral inhibition of neuronal development in epithelial cells (stops the development into neurones)
Autocrine signalling
Signalling molecules - hormones or chemical messengers.
Bind to autocrine receptors in the same cell - leads to changes within the cell.
Why is cell signalling specific?
Needs the specific receptor. It depends on if it is expressed in that cell type.
How do cells response differently to the same signal?
Depends on the reception and interpretation of the signal by target cell (not just the signal itself)
Acetylcholine is present in its of cells but acts differently.
How can multiple signals affect cells?
The signals ABC may promote survival.
The signals ABCDE promote (survival) and growth.
What is the difference between rapid and slow responces?
Rapid responses - causes changes the activity of proteins already present in the cell.
Slow - Requires changes in gene expression and protein synthesis - causes more profound affects
How receptors act in cell signalling?
Protein and peptide signals - Large and hydrophilic molecules the cannot pass through the plasma membrane, so they bind to receptors on the membrane.
Steroid - Small and hydrophobic so they can pass through the plasma membrane and so bind to receptors on the nucleus of cytoplasm
