Skin cell characteristics

The total skin surface of an adult is 4-6 m2. Skin consists of 3 layers: epidermis, dermis, dermis, and skin appendages. In which:
1.1 Epidermis Epidermis, also known as epidermis. This is the outermost layer of the skin.
The epidermis has no blood vessels, but they are nourished by blood vessels in the dermis. The average thickness of the epidermis is 0.5 - 1 mm, but it can be thicker or thinner depending on the skin of each location on the body. In particular, the thinnest part of the epidermis is in the area around the eyes, the thickest is in the skin on the soles of the feet and palms.
Epidermis is divided into 5 layers: basal layer, spiny layer, granular layer, light layer and stratum corneum.
The stratum corneum The stratum corneum is the uppermost layer, the cells are completely flattened, the cytoplasmic membrane is thick, the nucleus disappears.
Most of the cells present in the epidermis are keratinocytes, which originate from the deepest cells in the epidermis, also known as the basal layer. Newly generated keratinocytes migrate towards the surface of the epidermis. Once the keratinocytes have reached the surface of the skin, they will gradually become keratinized and slough off the skin and then be replaced by newer cells. This is called dermal keratinization.

Light layer This layer only appears in the palm and foot areas. The light layer above the granular layer consists of clear, homogeneous, nucleusless, flattened cells, arranged in 2 or 3 rows.
These cells contain eleidin, which is formed by liquefaction of the inner horny granules containing many disulfite groups.
Granular layer The cells of the granulosa layer consist of 3 to 4 rows, they are flattened, located on the spiny layer. The cytoplasm contains keratohyalin granules. When keratohyanlin granules appear, it means that the process of keratinization has begun.
The thickness of the granule layer will depend on the degree of keratinization. The seed layer will be thick where the stratum corneum is thick.
Spinal layer The squamous cells are located on the basal layer, with 5 -10 rows of cells. The squamous cells are located close to each other, connected by cytoplasmic bridges, more pronounced in the basal layer.
The squamous cells are also capable of reproduction by mitosis. The mitotic activity of the basal layer and the spine layer are both strong and continuous. During the period of 19-20 days the human epidermis will be renewed once.
Basal layer In the basal layer there are 2 cells called basal cells, also known as reproductive cells and pigment cells.
The epidermis contains dendritic cells (langerhans), which are part of the skin's immune system. They work to prevent foreign substances from entering the skin.
The condition of the skin on the epidermis will accurately reflect the health of the skin whether it is getting enough moisture.

1.2 Dermis The dermis is the middle layer in the structure of the skin. This is the thickest layer of skin, containing a lot of collagen and eslatin to help make the skin more elastic and supple. It contains many important proteins with collagen responsible for supporting the skin structure and elastin helping to restore the skin.
The dermis consists of spindle-shaped fibrous cells that have the effect of scaring the skin. Organization of rhombohedral or astrocytes, it can turn into macrophages that play an important role in body defense. Plasma cells participate in the metabolism of heparin and histamine.
The dermis also contains nerves, sweat glands, sebaceous glands, hair follicles, and blood vessels.
Nerves in the dermis will reflect, know the sensation of pain, irritation, high temperature or great pressure. In certain areas of the skin, such as the fingertips and toes, there are more nerves than in other areas that are more sensitive to the touch.
Sebaceous glands secrete oil to help retain moisture and protect the skin. When the sebaceous glands secrete too little oil, especially in the elderly, it will cause dry skin and easily form wrinkles. Conversely, when the sebaceous glands are overproduced during puberty, it can lead to acne.
Hair follicles produce hair all over the body. Hair on the skin has the effect of regulating body temperature, protecting from injury from external agents.
Blood vessels help provide nutrition to the skin and regulate body temperature. High temperatures will cause blood vessels to dilate and allow a large amount of blood to circulate near the surface of the skin to reduce heat, and when it is cold the blood vessels will constrict to help keep the body warm.
In each different location, the number of nerves, hair follicles or sebaceous glands will also change differently.

1.3 The dermis The dermis is below the dermis, containing connective tissue and fat molecules, so the dermis is the subcutaneous fat layer. The dermis is like a cushion that protects and insulates the tissues beneath the skin from mechanical and thermal trauma.
Subcutaneous fat layer will change more or less thickness depending on each part of the body.
In the aging process, there is loss of fatty tissue under the skin, causing wrinkles and other signs of skin aging.
There are many diseases related to the skin, including melanoma, also known as melanoma - a form of skin cancer. Melanoma can appear anywhere on the body. Initially a skin lesion resembling a mole or freckle, only a few millimeters in diameter, the area grew rapidly. The skin is flat at first, then becomes thick and raised. Some cases are accompanied by itching or pain. As the lesion progresses, it may bleed easily.
One of the main factors that cause melanoma is direct skin exposure to the sun during times of extreme sunshine like midday. Therefore, it is necessary to pay attention to preventing and reducing the progression of melanoma:
Limit sunlight exposure, especially from 10 am to 4 pm Need to wear a wide-brimmed hat, carefully cover the skin with How to wear a dark cloth mask, sunglasses, and use sunscreen properly. Regularly monitor the appearance and progression of skin lesions or unusual moles on the body. Visit your doctor and have regular skin checkups with your dermatologist if there are any abnormalities in your skin.