In this work, we propose to talk about which cells cover the surface of the skin. What is skin and what layers it consists of. To begin with, it performs many different functions, including:
- aesthetic;
- protection against mechanical damage;
- protection against thermal damage;
- protection against biological damage;
- touch;
- enrichment with oxygen.
Agree, all this is necessary for our life. The skin consists of several layers: the epidermis, dermis and hypodermis. Today we will especially pay attention to the uppermost layer - the epidermis. Consider what layers the epidermis is formed from, its thickness, and for how long it is completely able to update.
Epidermis
So which cells cover the surface of the skin? These are the cells of the epidermis layer. We see him, he is a stratum corneum. This is an inanimate shell, it peels off over time, that is, completely dies. There are absolutely no blood vessels in the epidermis. But in the depths of this layer are living cells. They divide and gradually make their way to the upper layer, while the cells themselves die and turn into scales.
Water practically cannot get under this layer, but fat-soluble substances penetrate practically without problems. Why is this happening? Cell membranes are composed of fats, they are able to dissolve others in themselves.
Epidermal cells
Like any other organs, our skin is made up of cells. Now we will analyze which cells cover the surface of the skin, that is, what particles the epidermis consists of.
The first thing worth mentioning is the keratinocytes that produce keratin. They are divided into three groups:
Keratinocytes are always in motion, they move along the layers of the epidermis, trying to reach the upper layer. During this, a very strong protein is produced - keratin. When they lose the nucleus, they become like a sac, now they are called corneocytes. When the cells reach the top, they simply fall away, and the next keratinocyte will come to this place. This process occurs quickly in a young body, and with age, all processes slow down.
Thickness
We figured out which cells cover the surface of the skin, but did not say anything about the thickness of the layer we are considering. It is not uniform everywhere. There are places where the thickness reaches two millimeters, and in some areas of our body it is equal to seven hundredths of a millimeter. The thinnest spots of the epidermis are equal to the thickness of the plastic film.
For example, compare the skin on the heels, arm and eyelids of the eyes. Agree, everywhere the thickness is different. Moreover, keratinization is more pronounced on the heels, and the skin of the eyelids is always smooth and delicate. The genitals also have a very thin layer of the epidermis (approximately 0.1 millimeters).
Update
We discussed which cells cover the surface of the skin. The world around is a rather fascinating subject, which allows children to learn a lot of new and interesting things, to discover new boundaries of knowledge. This topic is also included in the course of study.
Our appearance depends on skin renewal, a person loses about 10 billion cells a day, and this process slows down over time. On average, a person sheds 20 kilograms of skin per year. The healthier and younger our skin is, the more intensive is the exchange of cells, old ones are exfoliated, new ones replace them. When the body ages, the process slows down, so wrinkles appear. Together with dead cells, many harmful substances go away. It is the epidermis that prevents harmful bacteria from entering the body. The update takes place over a period of 21 days to three months, it all depends on age.
Epidermis layers
The question of which cells cover the surface of the skin, class 4 of the course of the surrounding world must necessarily include. Indeed, from childhood, people should know that the skin is our shield. If you do not care for her, then the whole body will suffer.
You need to know that the epidermis also includes several layers:
- basal;
- prickly;
- grainy;
- brilliant;
- horny.
With all this, the stratum corneum consists of approximately 15 levels. The upper layers of cells can be considered dead, because they do not have the ability to divide, and the inner ones have a nucleus, so they are alive. The border itself separating dead and living cells is in a prickly layer.