SkinStructure, Accessory Organs, and Functions
Thehuman skin is anatomically segmented into three layers namelyepidermis/superficial layer, dermis (intermediate layer), andhypodermis (the basal layer). Within one or more of these layers,distinct accessory organs occur and these include the sweat glandsand sebaceous glands. This essay examines the layers of the skinalongside the accessory organs and highlights the functions of each.
SkinStructure and Functions
Epidermisis the skin`s topmost layer which serves as the chemical and physicalobstruction between the external and internal body surroundings. Thecells present are the keratinocytes which function by synthesizingkeratin. Epidermis has five sub-layers from the deepest end namelythe stratum basale (innermost sub-layer), stratum spinosum, stratumlucidum, stratum granulosum, stratum corneum (the most superficiallayer). The innermost portion, stratum basale, comprises of dividingand non-dividing keratinocytes linked to the basement by thehemidesmosomes. These cells divide to produce the overlyingsub-layers and besides, the layer has melanocytes which secretmelanin that pigments the skin. Stratum spinosum is formed as theunderlying stratum basale cells reproduce and it has Langerhanscells which give the skin its immune reaction properties. Stratumlucidum only persists in the thick epidermis and offers a layer ofactively dividing cells that generate the stratum granulosum. Stratumgranulosum forms a layer of transition cells towards the skin surfaceand has granular nuclei, aids in physical protection. Finally, thesurface has stratum corneum with keratin and cornified cells whichgive the skin its water-retaining barrier properties as well as thecapability to offer protection from physical injury (Montagna,2012).
Thedermis is the second layer it is richly supplied with blood vessels,sensory receptors, lymphatic vessels, and nerve fibers as well as thehair follicles and sebaceous and sweat glands. Nonetheless, the layerfunctions in homeostasis, nutrition of the skin, secretion, andexcretion of wastes and produces hemoglobin for skin coloration. Itstwo major sub-layers are the papillary and the reticular layers(Montagna,2012).
Alsocalled the subcutaneous layer, hypodermis comprises of adipose andslack connective tissues the adipose/fatty tissue insulates the skinagainst heat loss while the connective tissue attaches the organ tothe underlying muscles (Montagna,2012).
Accessoryorgans are three namely sebaceous glands, sweat glands, andceruminous glands. Sebaceous glands occur in the entire body excepton the hand palms and the feet soles, and function by secreting sebumto moisturize the hair, soften and lubricate the skin, preventevaporative water loss, and antiseptic, destroying pathogenicbacteria. Sweat (sudoriferous) glands are of two types namelyapocrine (respond to emotional stress) and eccrine (respond toelevated body temperature) glands which secrete watery fluid inthermoregulation or stress relief. Finally, ceruminous glands producecerumen (ear wax) that protects the ear from bacteria attack(Montagna,2012).
Theskin has three major layers called the epidermis, dermis, andhypodermis as well as three primary accessory glands namelysebaceous, sweat, and ceruminous glands all of which function ashave been discussed above.
Montagna,W. (2012). TheStructure and Function of Skin 3E.NY, U.S: Elsevier.