CELL SIGNALLING

Objectives
1-Describe and compare biological communication involving hormones, local mediators and neurotransmittersprocesses
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Objective number (1):
?Describe and compare biological communication processes hormones, local mediators and neurotransmitters involving

• According to their functions:
• Hormones:) signaling between cells in different circulation . (Thyroxin hormone ). tissues via the
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Local chemical mediators :(signaling between adjacent cells
in the same tissue (cytokines)

Cells have proteins called receptors that bind to signaling
molecules and initiate a physiological response Different
receptors are specific for different molecules, Dopamine
receptors bind dopamine, insulin receptors bind insulin, nerve
growth factor receptors bind nerve growth factor, and so on.
How Do Cells Recognize Signals?
we have also intracellular receptors for hydrophobic
Molecules

molecules(ligand) outside the cell and then transmit the signal
through a sequence of molecular switches to internal signaling
pathway. and which in response to ligand binding brings about
regulation of a cellular process. In the unbound state a receptor is
functionally silent.
Hydrophilic receptors :- outside the cell On the membrane
Hydrophobic receptors:- inside the cell On the Nucleus or
cytosol