Cell Signaling

Autocrine cell communication

When a cell secrets ligands to be used in its own cell for example cancer cells

Paracrine cell communication (local regulators)

When the cell secrets ligans to be used in a local area or cells that are near it For example neurotransmitters

Endocrine cell communication

When the ligand / hormone has to go over large distances using the bloodstream for example insulin

Juxtacrine cell communication

Direct contact between the so that is sending the ligand and the cell that is receiving and responding to it via a surface receptor for example plasma desmata

Hydrophobic ligands

For hydrophobic ligands they can diffuse directly through the cell membrane so they can go straight to the nucleus ; use intracellular receptor

Signal transduction pathway: reception

The receptor may be located on the cell membrane or inside the cytosol of the target cell. The ligand binds to the receptor causing a confirmational shape change triggering the next step in the process.

Hydrophilic ligands

Due to the fact that the cell membrane is hydrophobic and the ligands are hydrophilic they must pass through a cell membrane receptor once they pass they trigger a series of chemical reactions

Signal transduction pathway: transduction

Series of chemical reactions which could be signal amplification, kinase, phosphatase, enzymes using secondary Messengers

Kinase

Addition of a phosphate group

Phosphatase

Removal of a phosphate group

Secondary Messengers

Helps the process

Signal transduction communication :response

Ultimate result

Negative feedback

Negative feedback is when the system returns to its original condition to maintain homeostasis meaning that there's an increase in stimuli and a decrease in the response

Positive feedback

Positive feedback magnifies the cells processes meaning that there's an increase in stimuli and an increase in response

Signal amplification

When one molecule activates multiple molecules amplifying the cell's response to the signal