Tanno and Iguda managed to navigate the Microwidget out of Professor Wendy through a pore in her skin in a droplet of sweat. As they fell towards the ground, they were saved by re-enlarging the sub to full size in the lab.

Sweat is produced to help us cool down (when it evaporates it takes away heat from the skin surface) but there is a lot more to skin than that!

Sticking out of the skin surface are hairs. Each hair is connected to a muscle which, when it contracts, pulls the hair upright. When this happens, a layer of air is trapped, which helps insulate the body and stops heat from escaping.

On a cold day you can see the hairs standing upright to help keep us warm, and the contracted muscles show up as goosebumps!

close up photo of human skin
Image credit: Alex Laude, Newcastle University
shiny dark skin with fine hairs
Image credit: Angela Roma on

The thinnest area of skin is on your eyelids.

The dead layer is constantly being worn away and many of the cells can be found in household dust.

The skin is made up of layers. The top layer is called the epidermis and is made up of tiny building blocks called cells, a little like a brick wall. The very top layer is made of flat, hard, dead cells that make the skin waterproof and is protection from infection. The next layer down is called the dermis, which is where the blood vessels, sweat glands and sensory receptors can be found. Further down still is a layer of cells containing fat, which helps insulate us.

Skin cross section model

This model shows a cross section of the skin

Image credit: SOMSO® model from Adam,Rouilly

Sensitive skin

The skin contains a number of different receptors that allow the body to pick up information from the immediate world outside. These receptors detect touch, pressure, pain, heat and cold.

Activity 1

Investigating how skin senses temperature

1) Set up 3 bowls, the first should contain ice-cold water, the second hot water from the tap (nothing hotter!) and the third should be left at room temperature.
2) Place your left hand in the cold water, and your right hand in the hot water for one minute.
3) After this time, place both hands in the bowl of room temperature water (be careful not spill any water doing this).
4) What does each hand feel like? Does one feel warmer than the other? If so, which one?

What does this tell us about how the skin detects temperature?

Photo by cottonbro from Pexels

Activity 2

Investigating your sense of touch

This requires a partner.

1) Close your eyes. Your partner then touches the skin on the back of your hand with the point of a fine tip pen (be careful not to press hard) just enough to make a mark.
2) With your eyes still closed, now you use the pen to try and touch the skin in exactly the same place.

3) Now open your eyes and see how far apart the two dots are. The closer they are, the more sensitive the skin is to touch.
4) Repeat the experiment on different parts of the skin and arm.

Is the distance between dots different in different places?  Which parts are more sensitive? Can you think of any reasons?

You can go to the previous PostcardsFromTheBody secret pages by clicking the places below.

MouthStomachSmall Intestine
Photo of PostcardFromThe Mouth
Large IntestineBloodHeart
PancreasImmune System
PostcardFromThe Pancreas