19. Skin and appearance
Appearances vary
The human appearance can vary a lot. Some of your classmates may be easy to distinguish from one another, whereas others may be harder to tell apart from a distance. A human's appearance is partially determined by their genome. This means that we have received hereditary factors that influence our appearance from our parents.
Things like hair color and face shape are determined by the genes you inherit from your parents. Even your weight is influenced by your genes.
However, humans also have the ability to influence their appearance themselves. For example, hair color and length can easily be modified by visiting the barber or a hairdresser.
Each human is unique, and there is no one "right way to look". All people are valuable no matter what their appearance is like.
What are the functions of your skin?
The human skin fulfills many functions. Its most important function is to protect our bodies from the outside world. However, the skin also does many other things, such as the following:- It protects us from radiation, microbes and chemicals.
- It insulates us from water.
- It helps to regulate our body temperature with the help of blood vessels.
- It senses cold, heat, pressure and pain.
- It produces Vitamin D.
Skin
Skin protects our bodies from the outside world. Because of this, the cells of our skin are tightly connected and extremely durable. When skin cells wear out, they are replaced with new skin cells. The part of the skin that consists of dead cells is known as the stratum corneum or the horned layer.
New skin cells are formed in the layer located below the stratum corneum. This layer is known as the epidermis.
The skin protects itself from harmful solar radiation by tanning. However, all solar radiation is not harmful. This is because the skin also uses solar radiation to produce important vitamin D. When your skin tans during the summer, the change in your skin color is not permanent, because the skin cells that have changed their color will soon die and flake away.
The color of the cells produced by the epidermis, however, is permanent. It is an inherited characteristic that is determined by your genes. This means that if two people have a dark skin color, their children will also have a dark skin color.
A layer of dermis is located below the epidermis. The dermis contains sebaceous glands and sweat glands. Sebaceous glands produce fat-like sebum, which protects the skin. If a sebaceous gland becomes infected, the result is a pimple. Sweat glands produce sweat. The body emits sweat when it needs to lower its temperature. The dermis also contains large numbers of receptor cells, which sense various kinds of information.
New skin cells are formed in the layer located below the stratum corneum. This layer is known as the epidermis.
The skin protects itself from harmful solar radiation by tanning. However, all solar radiation is not harmful. This is because the skin also uses solar radiation to produce important vitamin D. When your skin tans during the summer, the change in your skin color is not permanent, because the skin cells that have changed their color will soon die and flake away.
The color of the cells produced by the epidermis, however, is permanent. It is an inherited characteristic that is determined by your genes. This means that if two people have a dark skin color, their children will also have a dark skin color.
A layer of dermis is located below the epidermis. The dermis contains sebaceous glands and sweat glands. Sebaceous glands produce fat-like sebum, which protects the skin. If a sebaceous gland becomes infected, the result is a pimple. Sweat glands produce sweat. The body emits sweat when it needs to lower its temperature. The dermis also contains large numbers of receptor cells, which sense various kinds of information.
Terminology
| Term | Explanation |
|---|---|
| skin | The outermost part of the human body. Protects the body from the outside world. |
| genome | The inherited information an individual receives from its parents. |