Lecture 9 - BIO 317 Principles of Cellular Signaling...

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1 BIO 317 Principles of Cellular Signaling Lecture 9 Mg ++ Causes a Voltage-Dependent Block of NMDA Receptors From: Ion Channels and Disease by Frances Ashcroft Voltage dependence of whole-cell glutamate-activated current • The current-voltage relation deviates from linearity in the presence of Mg ++ because Mg ++ produces a voltage-dependent block of the channel • Depolarization causes Mg ++ to move out of the NMDA receptor relieving the block and allowing cations (Ca ++ , Na + , K + ) to flow through the channel
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2 Sensory Transduction Membrane sensors consisting of specialized ion channels translate sensory information into electrical signals sensory transduction channels generator potential How does the nervous system detect properties of the environment? Many sensory modalities: smell taste vision hearing touch pain temp. osmolarity C0 2 pH heat radiation electrical potentials Schematic of Sensory Transduction stimulus generator potential spike train or neurotransmitter release receptor molecule transduction channel receptor molecule responds to a specific stimulus receptor molecule may be the transduction channel or may communicate to transduction channel via second messenger generator potential is caused by opening (most common) or closing of cation channels: open depolarization close hyperpolarization generator potential controls rate of APs or rate of neurotransmitter released
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3 Sensory Receptors Sensory receptors found in human skin Sensory receptors involved in proprioception Sensory Adaptation Many sensory receptors exhibit ‘sensory adaptation – Sensory receptor response fades even though stimulus is held constant – Serves as an auto-gain / auto-zeroing feature that • Negates steady level of background stimulation • Allows receptor to provide useful information over a broad range of stimulus intensities
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Lecture 9 - BIO 317 Principles of Cellular Signaling...

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