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epiderm是什么意思，epiderm翻译
Epiderm: The Outer Layer of the Skin
The epidermis, often referred to as the epiderm, is the outermost layer of the skin. It is a thin, dead layer of stratified squamous epithelial cells that serves as a waterproof barrier to protect the body from the external environment. The epiderm is constantly shedding and being replaced by new cells from the layer of skin beneath it, called the dermis.
Structure of the Epidermis
The epidermis is composed of several layers, each with its own unique functions. The basal layer, also known as the stratum basale, is the deepest layer of the epidermis. It is responsible for the production of new skin cells, or keratinocytes, which migrate to the surface of the skin as they mature. As these cells move upwards, they undergo a process called keratinization, where they fill with a protein called keratin and eventually die.
The next layer above the basal layer is the stratum spinosum, which contains cells that have begun the process of keratinization. These cells are connected to each other by structures called desmosomes, which provide strength and stability to the epidermis. The stratum spinosum is followed by the stratum granulosum, which contains cells that are further along in the process of keratinization. These cells produce a protein called filaggrin, which helps to maintain the skin's barrier function.
The top layer of the epidermis is the stratum corneum, which is composed of flattened, dead skin cells called corneocytes. These cells are held together by a substance called cornified envelope, which provides a protective barrier against environmental factors such as bacteria, chemicals, and UV radiation. The stratum corneum is constantly shedding and being replaced by new cells from the underlying layers of the epidermis.
Functions of the Epidermis
The epidermis serves several important functions in the body. Firstly, it acts as a waterproof barrier, preventing water from entering the body and protecting against the entry of harmful pathogens such as bacteria and viruses. Secondly, the epidermis helps to regulate body temperature by preventing excessive heat loss from the body. Thirdly, it provides protection against UV radiation from the sun, which can be harmful to the body's cells.
In addition to these functions, the epidermis also plays a role in the body's immune response. The cells of the epidermis produce a substance called interleukin