B6A11Coordinate

Chemical messengers receptors one cell releases a

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Unformatted text preview: leases a molecule 1. Synapse: the messenger (neurotransmitter) diffuses (messenger) that initiates a across a small gap between a neuron and its target cell. change in another cell by binding to a protein receptor 2. Paracrine: the messenger (local regulator, paracrine factor, on that target cell. growth factor, cytokine) diffuses Nitric oxide (NO) Carbon monoxide (CO) Ethylene (H 2C=CH 2) Mechanisms of Hydrophilic Signal Molecule Action • Hydrophilic signal molecules — most amino acid class – Water soluble. – Short half-life: minutes Mechanisms of Messenger Action • Hydrophilic signal molecules — most amino acid class – Water soluble. – Short half-life: minutes – Do not enter target cells. Act as ligand by binding to protein receptor on cell surface. • Lipophilic signal molecules — steroids & thyroid hormones – Water insoluble. Must be transported in plasma by carrier proteins. – Carrier proteins also protect hormone from degradation. Half-life longer: 1 –2 hours....
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