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The epidermis is the outermost of the three layers that comprise the skin, the inner layers being the dermis and hypodermis. [1] The epidermis layer provides a barrier to infection from environmental pathogens [2] and regulates the amount of water released from the body into the atmosphere through transepidermal water loss.
Human skin often may come from autopsies or plastic surgeries. [20] The test product is applied to the membrane via the top chamber. The bottom chamber contains fluid from which samples are taken at regular intervals for analysis to determine the amount of active cells that has permeated the membrane at set time points.
The dermis is composed of three major types of cells: [3] fibroblasts, macrophages, and mast cells.. Apart from these cells, the dermis is also composed of matrix components such as collagen (which provides strength), elastin (which provides elasticity), and extrafibrillar matrix, an extracellular gel-like substance primarily composed of glycosaminoglycans (most notably hyaluronan ...
The human stratum corneum comprises several levels of flattened corneocytes that are divided into two layers: the stratum disjunctum and stratum compactum. The skin's protective acid mantle and lipid barrier sit on top of the stratum disjunctum. [5] The stratum disjunctum is the uppermost and loosest layer of skin.
It forms the outermost layer of the skin and the inner lining of the mouth, esophagus and vagina. [2] In the epidermis of skin in mammals, reptiles, and birds, the layer of keratin in the outer layer of the stratified squamous epithelial surface is named the stratum corneum. Stratum corneum is made up of squamous cells which are keratinized and ...
The human skin is the outer covering of the body and is the largest organ of the integumentary system. The skin has up to seven layers of ectodermal tissue guarding muscles, bones, ligaments and internal organs. Human skin is similar to most of the other mammals' skin, and it is very similar to pig skin.
Ointments are more occlusive than aqueous creams, which are more occlusive than lotion. [5] Water loss through the skin is normally about 4–8 g/(m 2 ⋅h). A layer of petrolatum applied to normal skin can reduce that loss by 50–75% for several hours. [4] Oils naturally produced by the human body moisturize through this same mechanism. [2]
[5] [7] The solvent that is used as a dispersion medium can be aqueous, organic, inorganic, or a system of different solvents. [5] Topical gels are used as a contact or transport medium for active drugs to act on [4] or through the skin. [9] The active drug molecules are entwined into the 3D mesh of the gel and delivered to the site of action.