How to find sensitive parts?

Experimental method:

When you put your tongue in front of the mirror, you can see that there are many tiny organs called taste buds on the surface and back of your tongue, which is how people feel the taste. Taste, like smell, is caused by slow chemical reactions.

Taste buds transmit taste signals to the brain through taste nerves, which makes people feel the taste. People have four basic tastes: sweet, sour, bitter and salty. The taste buds responsible for these four flavors are unevenly distributed on the tongue surface. You might as well try to find out where the taste buds are most concentrated.

Take a little sugar, salt, vinegar and black coffee powder, then prepare a glass of water and a clean brush. Soak the brush in clean water, shake it twice, dip it in a little sugar, and touch the tip, edge and root of the tongue. You will feel that there is a part that is most sensitive to sweetness, that is, the tip of the tongue. Rinse your mouth repeatedly with clear water, clean the brush, and then dip in salt, vinegar and black coffee powder in turn. You will find that the edge of the tongue is most sensitive to sour taste, the most sensitive part to bitter taste is the root of the tongue, and all parts of the tongue are sensitive to salty taste.

Obviously, taste buds do have a division of labor for various tastes. But life experience tells us that their division of labor is not absolute. The actual situation is much more complicated than the above experiment, and sometimes one flavor can mask or offset another or several flavors. For example, the sweetness of sugar can offset the sourness of lemon. People who are not used to spicy food take a bite of spicy tofu, which is too spicy to close their mouths, and then they won't feel what it tastes like when they eat other dishes.

Knowledge expansion:

In fact, not only different parts of the tongue are sensitive to taste, but also different parts of the human body are sensitive to touch.

Take a hairpin and separate its feet so that the distance between the tops of the two feet is 4 cm. Touch the skin on your arm. If you close your eyes, you can't feel whether one foot of the hairpin is touching you or both feet are touching your skin at the same time.

Take another hairpin, hold your foot, so that your foot surface is only 2 mm apart, and try it on your finger in the same way. Even if you close your eyes and turn your head, you can quickly and accurately feel one foot or two feet touching your fingers.

Obviously, some parts of the human body feel very sensitive, such as fingers. No wonder people often say "ten fingers linked to one heart". And some parts feel dull. The arm is by no means the least sensitive part of the human body.

If you are interested, you might as well use a simple sensory tester-hairpin to test the sensitivity of various parts of the body and find out the most sensitive and dull parts.