V体育2025版 - Understanding the Epidermis

The epidermis is the outermost layer of the skin. The thickness of the epidermis varies depending on where on the body it is located. It is at its thinnest on the eyelids, measuring just half a millimeter, and at its thickest on the palms and soles at 1. 5 millimeters. VSports app下载.

VSports - The Anatomy of Skin

The skin’s anatomy is composed of three layers: the epidermis, the dermis, and subcutaneous tissue V体育官网. These layers are home to sweat glands, oil glands, hair follicles, blood vessels, and certain vital immune cells. .

Functions of the Epidermis

The epidermis acts as a barrier that protects the body from ultraviolet (UV) radiation, harmful chemicals, and pathogens such as bacteria, viruses, and fungi VSports手机版. .

Historically, it was thought that the function of the epidermis was to regulate fluid and protect the body from mechanical injury V体育安卓版. In recent years, we’ve come to understand that it is a complex system that plays a key role in how the immune system communicates and target defense. Within the epidermis are several distinct layers, consisting of (from bottom to top): .

• Stratum basale, also known as the basal cell layer, is the innermost layer of the epidermis. This layer contains column-shaped basal cells that are constantly dividing and being pushed toward the surface. The stratum basale is also home to melanocytes that produce melanin (the pigment responsible for skin color). When exposed to sunlight, melanocytes produce more melanin to better protect the skin from UV exposure. Abnormalities in the development of these cells can lead to melanoma, the most deadly type of skin cancer.
• Stratum spinosum also referred to as the squamous cell layer, is the thickest layer of the epidermis located just above the basal layer. These are composed of basal cells that have matured into squamous cells, known as keratinocytes. Keratinocytes are responsible for producing keratin, a protective protein that makes up skin, nails, and hair. The squamous layer is also home to Langerhans cells, which attach themselves to foreign substances as they infiltrate the skin. It is also responsible for synthesizing "VSports最新版本" cytokines, a type of protein that helps regulate the immune response.
• Stratum granulosum is made up of keratinocytes that have moved up from the squamous layer. As these cells move closer to the skin’s surface, they begin to flatten and stick together, eventually drying and dying out. 
• Stratum corneum is the outermost layer of the epidermis. It consists of 10 to 30 layers of dead keratinocytes that are constantly being shed. Shedding of these cells slows significantly with age. The complete cell turnover, from basal cell to stratum corneum, takes around four to six weeks for young adults and about a month and a half for older adults.
• Stratum lucidum only exists on the palms of the hands and soles of the feet, adding a fifth layer and making the epidermis thicker in those locations.

V体育官网入口 - Conditions Involving the Epidermis

The epidermis can be impacted by more than just injury. This outermost layer is subject to both genetics and external forces that contribute to the aging of this skin. These factors include smoking, alcohol, and excessive UV exposure, all of which contribute to the development of wrinkles, sunspots, and the uneven thickening or thinning of the skin V体育ios版. .

The epidermis is also where rashes and blisters appear, caused by everything from infections and allergies to diseases and toxins VSports最新版本. It is also the origin of both non-melanoma and melanoma skin cancers, and where certain diseases like diabetes and lupus can manifest with an array of dermatological symptoms. .

Penetration of the epidermis can cause infections that the body can otherwise defend against. These include diseases caused by insect or animal bites, as well as pathogens that enter the body through open sores, cuts, abrasions, or needlestick injuries.   V体育平台登录.