Chapter 11 - Carbohydrates and Cutaneous Wound Healing

Abstract

Skin is the largest immunologically competent organ in the body. The skin has two layers, epidermis and dermis. The epidermis is rich in cells that are specialized in the formation of keratin and are called keratinocytes. The epidermis consists of a stratified layer of cells stretching from the basement membrane below to the stratum corneum above. The area of the basement membrane far exceeds that of the surface of the stratum corneum because multiple dermal papillae project from the surface of the dermis and only about 12% of the basal cells are proliferating at any one time in normal skin. These papillae are formed by loose approximations of collagen bundles referred to as the papillary dermis, which lies on the relatively much thicker reticular dermis. Collagen bundles in the reticular dermis are thicker and more condensed. The dermis consists of an organized structure of elastin and collagen fibers between which is a thick, viscous fluid made up of glycosaminoglycans (GAGs) and hyaluronan (HA). This arrangement of the dermis gives the skin its major biomechanical properties, allowing stretching and recoil and deformation without destruction. The dermis contains a complex vascular arrangement of capillary and venous plexuses. Within the dermis are adnexal structures of ectodermal origin—hair follicles, sweat glands, and sebaceous glands—which are lined with keratinocytes. This arrangement becomes particularly important when considering the mechanisms of wound healing.