batman
Forum Newbie
Topics: 9
Posts: 10
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Describe how, when dealing with sensory receptors, the term "threshold stimulus" refers to both modality and intensity of the stimulus?
Also, what is modality? I have an idea, but I'm not quite sure.
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| mildus
Forum Guru
Topics: 19
Posts: 614
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As far as I know, threshold stimulus refers to intensity of an adequate stimulus.
Modality is type of stimulus (visual stimulus for rods and cones, mechanical stimulus for Pachinian corpuscle...).
Receptors can detect adequate stimulus (visual stimulus for rods and cones) but also some other (when somebody hits your eye, you'll see stars) but there has to be much higher intensity of an unadequate stimulus (when compared to an adequate stimulus) to reach treshold potential and evoke an action potential. So, there is a definition of an adequate stimulus saying that adequate stimulus is the one which can be detected by receptor with the smallest threshold.
So, threshhold potential is reached when enough number of voltage gated Na channels is open due to strong enough adequate stimulus.
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