Block 5 Skin Sensitivity Lab Hypothesis: The fingertips will be the most sensitive because they are used the most for touching things all of the time. The area that will be the least sensitive is the shins because we are constantly bumping into things with our shins so they need to be less sensitive to pain. Data: TEST |Index Finger Tip | Thumb | Palm | Back of Hand | Forearm (inside) | Fore- head | Nose | Back of Neck |

Shin | |1 probe |+ |+ |+ |+ |- |- |+ |- |- | |1 mm |+ |- |+ |+ |+ |- |+ |+ |- | |3 mm |+ |+ |+ |+ |- |+ |+ |+ |+ | |5 mm |+ |+ |+ |- |+ |+ |+ |+ |+ | |10 mm |+ |+ |+ |+ |- |- |+ |- |+ | |TOTALS |5 |4 |5 |4 |2 |2 |5 |3 |3 | |CLASS AVG |4. 3 |4. 0 |3. 3 |2. 8 |3. 0 |2. 9 |3. 0 |3. 0 |2. 9 | | Conclusion: The most sensitive areas of my body were my fingertips, palm, and nose. The least sensitive areas of my body were my forearm and forehead.

This partly supported my hypothesis because the fingertips were among the most sensitive but my shins were not the least sensitive. My results were fairly close to the rest of the class. The only two areas that were more than a point apart between my data and the class average were my palms and my nose. These areas were more sensitive to me than the rest of the class. Some areas might be more sensitive because they are involved with touching and bumping into things than others. For example my fingertips were far more sensitive than y forearms because I use them to touch things all the time and the touch receptors are more dense in them. It makes sense that touch receptors are more dense in areas that are involved in more touching than others. In places where a lot of bumping into things occurs such as the shins, touch receptors would be less dense because you wouldn't want to feel all that pain all the time. Meissner’s corpuscles are light touch receptors in the skin which are prone to touch sensitivity.

They are located just under the epidermis, which makes sense because they are closer to the outside so they can be more sensitive to light touch. Pacinian corpuscles are touch receptors located deeper in the dermis in the skin that respond to touch and pressure. They are good for feeling rough surfaces and determining vibration. The location of these receptors are deeper in the skin because they are designed to feel pressure so when something pushes down on the skin they can respond.

The homunculus diagram is showing how the human body would be built if it was in proportion to the amount of sensory and motor brain power needed to control each part. The hands and mouth are bigger because they require more brain power to control. In the somatosensory cortex diagram the mouth and hands are also bigger which might explain why the skin in both of these areas is more sensitive than in other parts of the body. In both diagrams the bigger body parts require more control from the brain and have more sensitive skin.