chapter 45A - 45 Sensory Systems 45 Sensory Systems Sensory...

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Unformatted text preview: 45 Sensory Systems 45 Sensory Systems Sensory Cells and Transduction of Stimuli Chemoreceptors: Responding to Specific Molecules Mechanoreceptors: Detecting Stimuli that Distort Membranes Photoreceptors and Visual Systems: Responding to Light Sensory Worlds Beyond Human Experience 45 Sensory cells transduce information about an animals external and internal environment into action potentials. The interpretation of action potentials as particular sensations depends on which neurons in the CNS receive them. 45 Membrane receptor proteins of sensory cells cause ion channels to open or close, generating receptor potentials . Receptor potentials can spread to regions of the sensory cell plasma membrane that generate action potentials, or influence release of neurotransmitter from the sensory cell. 45 Figure 45.1 Part 1 Temp-sensitive cation channel Sensory Cells and Transduction of Stimuli 45 Sensory Cells and Transduction of Stimuli In ionotropic sensory detection , the receptor protein itself is part of the ion channel and, by changing its conformation, opens or closes the channel pore. In metabotropic sensory detection , the receptor protein is linked to a G protein that activates a cascade of intracellular events that eventually open or close ion channels. 45 Figure 45.1 Part 2 Figure 45.1 Part 2 Sensory Cells and Transduction of Stimuli 45 Sensory Cells and Transduction of Stimuli Sensory cells transduce physical or chemical stimuli into signals that are transmittable and interpretable. Most sensory cells (or receptor cells ) are modified neurons, specialized for detecting different kinds of stimuli, such as pressure, heat, or light. Sensory cells and other types of cells form sensory organs , such as eyes, ears, and noses. Sensory systems include the sensory cells, the associated structures, and the neuronal networks that process the information. 45 Sensory Cells and Transduction of Stimuli The affected receptor must trigger an action potential if the signal is to be transmitted by the nervous system. A change in the resting membrane potential of a sensory cell in response to a stimulus is called a receptor potential . Figure 45.2 Stimulating a Sensory Cell Produces a Receptor Potential 45 Sensory Cells and Transduction of Stimuli Some sensory cells respond less when stimulation is repeated, a phenomenon called adaptation . The ability of animals to ignore continuous stimuli while remaining sensitive to changing stimuli is sometimes due to sensory cell adaptation. 45 CPS Question Which of the following is an example of adaptation of sensory cells? A. Going into deep sleep B. Discriminating different colors C. Ignoring your shoes as you walk D. Ignoring a boring lecture E. Detecting sound and light simultaneously 45 Sensory Systems Sensory Cells and Transduction of Stimuli Chemoreceptors: Responding to Specific Molecules Mechanoreceptors: Detecting Stimuli that Distort...
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This note was uploaded on 04/30/2008 for the course BIO 201 taught by Professor Masters during the Spring '08 term at Johns Hopkins.

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chapter 45A - 45 Sensory Systems 45 Sensory Systems Sensory...

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