Fibroblast The fibroblast is the large cell type of the dermis. These cells are responcible for the formation of procollagen and elastic fibers. Procollagen is terminally cleaved by proteolytic enzymes into collagen which aggregates and turned into cross-linked. These tightly cross-linked collagen fibers allow tensile strength and resistance to shear and other mechanical forces.(9,10) Collagen makes up 70% of the weight of the dermis, primarily Type I (85% of the total collagen) and Type III (15% of the total collagen). Elastic fibers constitute less than 1% of the weight of the dermis, but they play an tremendous functional role by resist deformational forces and returning the skin to its resting stage. Dermoepidermal Junction The dermoepidermal …show more content…
They are highly concentrated in the palms and soles and the axillae. Each gland comprise of a coiled secretory intradermal part that link up to the epidermis via a relatively straight distal duct. The general function of the sweat gland is to production and excretion of sweat, which cools the body by evaporation.(28) The thermoregulatory center in the hypothalamus controls sweat gland activity through sympathetic nerve fibers that innervate the sweat glands. Sweat excretion is trigger off when core body temperature reaches or exceeds a set point. Apocrine gland Apocrine glands are same in structure, but not identical, to sweat glands. They are found in the axillae, in the anogenital area, and, as modified glands, in the external ear canal (ceruminous glands), the eyelid (Moll's glands), and the breast (mammary glands). They produce odor and do not function prior to puberty, that means they probably process a vestigial function. The mammary gland is dealing with modified and highly specialized type of apocrine …show more content…
Others can overwhelm the body if applied in only one place, and are often cut into sections and applied to different parts of the body to avoid this, such as nitroglycerin. Many molecules, however, such as insulin, are too large to pass through the skin. Basic components of Transdermal drug delivery systems: 1. Polymer matrix: The mechanism of drug release depends upon the physicochemical properties of the drug and polymer used in the manufacture of the patches(17). These control the release rate of the drug from the patches. These are prepared by dispersing the drug in polymeric base solution. There are some polymers used in preparation of Transdermal patches: Natural polymers: such as, cellulose derivatives, Zein, Gelatin, Shellac, Waxes, Proteins, Gums and their derivatives, Natural rubber, Starch etc. Synthetic Elastomers: e.g. polybutadiene, hydrin rubber, polyisobutylene, silicon rubber, nitrile, acrylonitrile, neoprene, butyl rubber etc. Synthetic Polymers: such as, polyvinyl alcohol, polyvinylchloride, polyethylene, polypropylene, polyacrylate, polyamide, polyurea, polyvinylpyrrolidone, polymethylmethacrylate etc