Skin皮肤专题知识讲座.ppt

单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,*,*,Skin皮肤专题知识讲座,Kayi,Name?,Aging skin,skin,the largest organ in the body,protect,sense,regulate temperature,Production of Vitamin D,Clininians,Dermatology-dermatologist,Plastic and esthetic surgery-plastic surgeon,Keratinocyte,fibroblast,OBJECTIVE,Master,skin,structure and function,epidermis,-,keratinization:proliferation/differentiation,Acquaitance,Anomalies of skin-common skin diseases,Advance,Skin regenerative medicine,INTRODUCTION,epidermis,dermis,hypodermis,Dermis,Papillary layer,+,Reticular layer,第二节真皮,skin,dermis真皮,papillary layer 乳头层,reticular layer 网织层,appendages附属器,hair 毛,sebaceous gland 皮脂腺,sweat gland 汗腺,THE STRUCTURE OF SKIN,epidermis表皮,stratum corneum 角质层,stratum lucidum(透明层),stratum granulosum 颗粒层,stratum spinosum 棘层,stratum basale 基底层,nail 指(趾)甲,EPIDERMIS,主要细胞构成,keratinocyte,(,角质形成细胞,),non-keratinocyte,(,非,角质形成细胞,),differentiation,stratum corneum角质层,stratum granulosum颗粒层,stratum lucidum(透明层),stratification,stratum basale基底层,stratum spinosum棘层,（一）Epidermal stratification and differentiation,PSORIASIS,银屑病,red and white hues of scaly patches appearing on the top first layer of the epidermis(skin).,Langerhans cell,(,郞格汉斯细胞,),Langerhans cells,are,dendritic cells,(antigen-presenting immune cells)of the skin and mucosa,and contain large granules called,Birbeck granules,.They are present in all layers of the epidermis,but are most prominent in the,stratum spinosum,.,In,skin,infections,the local Langerhans cells take up and process,microbial,antigens,to become fully functional,antigen-presenting cells,.,Langerhans cells derive from the,cellular differentiation,of monocytes with the marker Gr-1(also known as Ly-6G/Ly-6C).This differentiation requires stimulation by,colony stimulating factor,(CSF)-1.,6,They are similar in morphology and function to,macrophages,.,Albinos,lack an enzyme called,tyrosinase,.Tyrosinase is required for melanocytes to produce melanin from the,amino acid,tyrosine,melanocyte,(,黑素细胞,),Melanocytes,are,melanin,-producing cells located in the bottom layer(the,stratum basale,)of the skins,epidermis,the middle layer of the,eye,(the,uvea,),the,inner ear,meninges,Melanin is a,pigment,that is responsible primarily for the color of skin.,No difference in melanocyte number between species.,The distribution and tyrosinase activity!,Melanoma(黑色素瘤):,4%of all diagnosed skin cancers,melanoma begins in the melanocytes,cells within the epidermis that give skin its color.Melanoma has been coined“the most lethal form of skin cancer”because it can rapidly spread to the lymph system and internal organs.With early detection and proper treatment,the cure rate for melanoma is about 95%.Once its spreads,the prognosis is poor.Melanoma most often develops in a pre-existing mole or looks like a new mole,which is why it is important for people to know what their moles look like and be able to detect,changes,to existing moles and spot new moles.,The Hair,Sebaceous Glands,Sweat Glands,The Nails,The Accessary Structures of the Skin,Acne vulgaris,(or,cystic acne,)is a common disease,characterized by areas of skin with scaly red skin,blackheads and whiteheads,pinheads,pimples,nodules and possibly scarring.Acne affects mostly skin with the densest population of sebaceous follicles;these areas include the face,the upper part of the chest,and the back.Severe acne is inflammatory,but acne can also manifest in noninflammatory forms.,2,The lesions are caused by changes in pilosebaceous units,skin structures consisting of a,hair follicle,and its associated,sebaceous gland,changes that require,androgen,stimulation.Acne occurs most commonly during,adolescence,and often continues into adulthood.In adolescence,acne is usually caused by an increase in,testosterone,which people of both genders accrue during puberty.,Alopecia Totalis,(,全頭脱毛症）,Alopecia,means loss of,hair,from the head or body.,baldness,Hemidesmosomes,(HD)are very small stud-or rivet-like structures on the inner basal surface of,keratinocytes,in the,epidermis,of skin.They are similar in form to,desmosomes,when visualized by electron microscopy.While desmosomes link two cells together,hemidesmosomes attach one cell to the extracellular matrix.,Desmosomes are molecular complexes of cell adhesion proteins and linking proteins that attach the cell surface adhesion proteins to intracellular,keratin,cytoskeletal,filaments.,The cell adhesion proteins of the desmosome,desmoglein and desmocollin,are members of the,cadherin,family of cell adhesion molecules.They are,transmembrane proteins,that bridge the space between adjacent,epithelial cells,by way of,homophilic binding,of their extracellular domains to other desmosomal cadherins on the adjacent cell.Both have five extracellular domains,and have calcium-binding motifs.,Age-associated skin changes include thinning,skin laxity,fragility,and wrinkles.Sun-exposed areas demonstrate additional aging changes,including dyspigmentation,premature wrinkling,telangiectasia,and actinic elastosis.,UVA,400 315 nm,UVB,315 280 nm,The,sun,emits ultraviolet radiation in the UVA,UVB,and UVC bands.The Earths,ozone layer,blocks 9799%of this UV radiation from penetrating through the atmosphere.Of the ultraviolet radiation that reaches the Earths surface,98.7%is UVA,Photoaging,UV and molecular and genetic changes,UVB ray is considered as a primary,mutagen,that can only penetrate through theepidermal,or outermost layer of the skin,resulting in DNA mutations.The epidermal layer does not contain any,blood vessels,or nerve endings but,melanocytes,and,basal cells,are embedded in this layer.Upon exposure to UVB rays,melanocytes will produce melanin,a pigment that gives the skin its color tone.However,UVB will cause the formation of freckles and dark spots,both of which are symptoms of photoaging.With constant exposure to UVB rays,signs of photoaging might appear and precancerous lesions or skin cancer may develop.,UVA rays are able to penetrate deeper into the skin as compared to UVB rays.Hence,in addition to the epidermal layer,the dermal layer will also be damaged.The dermis is the second major layer of the skin and it comprises collagen,elastin,and extrafibrillar matrix which provides structural support to the skin.However,with constant UVA exposure,the size of the dermis layer will be reduced,thereby causing the epidermis to start drooping off the body.Due to the presence of blood vessels in the dermis,UVA rays could lead to dilated or broken blood vessels most commonly visible on the nose and cheeks.,Photoaging:telangiectasia,pigmentation,Sunscreen,SPF:ratio of the minimal erythema dose(MED)of sunscreen-protected skin over the MED of unprotected skin.,Currently available products offer excellent protection from UVB and,to a more variable extent,from UVA;therefore,the regular use of sunscreens should offer protection against sunburn as well as photoaging,A waterresistant product maintains the SPF level after 40 minutes of water immersion,whereas a very water-resistant(formerly waterproof)product maintains the SPF level after 80 minutes of water immersion.,The UV exposure would be the strongest between 10am and 4pm and sun avoidance between this period of time is highly encouraged.If one cannot avoid exposure to the sun,clothing,hats and sunglasses that protects one from sun exposure should be fully utilized.Wide spectrum sun screens that have a sun protection factor(SPF)of at least 30 should be used when one gets frequent sun exposure.,chemicals,electricity,radiation,and heat,Burns,(Sulfuric acid,sodium hydroxide),