Lab 4 Human Nervous System TwO POINT DISCRIMINATION on different areas of the sk
ID: 205858 • Letter: L
Question
Lab 4 Human Nervous System TwO POINT DISCRIMINATION on different areas of the skin The distance at which an individual can differentiate one point varies ue to the size of the receptive field and number of receptors. from two points This procedure shows the relationship of receptor density and field size to discrimination. Obtain a pair of dividers that can be adjusted to varying distances apart. Have the volunteer close both eyes or look away. . Separate the dividers to about 20 millimeters and then lower both points so they gently poke the palm. Have the volunteer indicate whether one point or two points were felt. Shorten the distance between the dividers if two points were felt. Continue until you discover the closest distance the volunteer can differentiate two points from one point. Mix up the distances and use one point to keep the volunteer honest Record the distance in millimeters on Table 4-3. Repeat using the fingertip, ventral forearm, and dorsal forearm. Table 4-3 Two Point Discrimination Distance (mm) Body Region Dorsal forearm Ventral forearm Distance (mm) Body Region Palm Fingertip 20 11. Which area has the greatest discrimination or accuracy? chp 12. Which area contains a smaller receptor field size and a greater density of receptors? fungExplanation / Answer
13. Our skin allow us to identify several distinct types of sensations such as tapping, vibration, pressure, pain, heat and cold. Activities involve tactile or touch sense of the skin which allow us to distinguish different kind of stimuli upon the surface of the body. There are two properties that are used in two point discrimination one is high receptor density means receptor must be closly packed so that a probe stimulate one or more of them. Second property is receptive field size. Central nervous system (CNS) must have small receptive field . Each sensory receptor connect through a series of relay neuron with CNS neurons. A given central neuron respond to all information from its input area as if it coming from one point. This skinarea is called receptive field of central neuron.
Two point discrimination depend upon activating two separate population of neuron. To discriminate two closely placed points the receptive field of neuron must be small means receptor should be closly packed area so that two point very close together activate different receptor. Two point discrimination is inversly proportional to receptive field size and directly proportional to density of receptor.
According to table given above, on the arm , palm each sensory receptor gather information from large skin area than a area on fingertip. Fingertip have closly packed receptor because of small area. Therefore, fingertip has greatest discriminatio than arms and palm.
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