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Signals
external signals
chemical
hormones
nerotransimtters
growth factors
cell messengers
electrical
light
mechanical
Definition
ability for cells to communicate across body
New-Branch
applies to all cells in body
signal transduction
= process of transmission from ligand to affect DNA
1. Receptor recognition of ligand
2. Transduction = extracellular message becomes intracellular message
secondary messenger
potentially can be amplified to many messengers
allows for specificity and diversity
ie. same receptor different possible messengers and so responces
3. Transmission
secondary messenger must reach effector
4. Modulation of effector
by activating protein kinase (adds phosphors to proteins)
or activation of phophatases (removes phosphors from proteins)
5. Responds to initial stimulus
6. Termination of responce
pathways
gap junctions
protein cylinder
allows electrical or chemical passing (in particular Ca)
direct cell to cell conduits
cardiac and smooth muscles primary sites
allows for quick signal transport
see types in book
excretion to receptor
excretion to receptor to signal transduction
purpose
adapt to changes in environment
coordinate actions between cells
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