皮肤的构造与功能.pptx

,按一下以編輯母片標題樣式,#,按一下以編輯母片,第二層,第三層,第四層,第五層,皮肤的构造与功能,皮肤的构造与功能,第1页,Look at your skin,More than a covering,A vital organ,complex structure,Develop from the same tissues as the brain,皮肤的构造与功能,第2页,Skin facts,Surface area:about 2500 cm in a newborn baby,18000 cm in an adult.,About 6-16%of body weight:average 3 kg in a woman,perhaps 5 kg in a man.,thickness:varies on sites.thinnest on the eyelids and thickest on the palms and the soles.,皮肤的构造与功能,第3页,Three layers:epidermis,dermis,subcutaneous fat,皮肤的构造与功能,第4页,Epidermis,Thickness:35-50,m,only 20 m around eye,thicker on the palm and sole(mm),oxygen and nutrients from the dermis,Translucent,Basement membrane,Rete ridges,皮肤的构造与功能,第5页,Epidermis-2,All keratinocytes originate from basal layer,Move upward,change shape and loss nucleus,produce,skin protein(keratin),and fat(sphigolipid,ceramide),Corneocytes:dead,Resist to injury,keep water,皮肤的构造与功能,第6页,Epidermis-2,Desquamation(squames),Renew cycle:about 30 days,Psoriasis:4-7 times faster,Speed up:sunburn,peel,aging,皮肤的构造与功能,第7页,Epidermis-3,A model of“bricks and mortar”,Corneocytes,desmosomes,natural fat,up to 15%of the stratum corneum consists of water.,TEWL(transepidermal water loss),皮肤的构造与功能,第8页,Dermis,3000,m thick,keep resilience and supple,Contain blood vessels,nerves,hair roots and sweat glands,Fibroblasts make collagen and elastin,Ground substance:glycoprotein(hyaluronic acid,chrondroitin sulfate),maintain water,皮肤的构造与功能,第9页,Dermis-2,Collagen:75%,Elastic fibers:Elastin,5%,Stretch marks,Wound repair,Across lines,deep,large,Granulation tissue,Hypertrophic scar,Keloid,皮肤的构造与功能,第10页,Subcutaneous fat layer,Adipocytes,larger vessels and nerves,Depth differs from site and individual,Cushing,conserve body heat,store fat:women(buttocks and thighs),men(abdominal wall),cellulite,皮肤的构造与功能,第11页,Sebaceous glands,Part of hair follicles,in every part except palm and sole,Sebum:pH=4.2-5.6,protect skin and lubricate hair shaft,Mixture of sebum and sweat:,natural oil-in-water emulsion,kill some fungi,Influence by male hormone,most sensitive at puberty,on face and trunk,皮肤的构造与功能,第12页,Eccrine glands,Empty directly on to the skin,in every part except lips and glans penis,Produce sweat:mixture of water and salts,Regulate the,body temperature,Remove waste,皮肤的构造与功能,第13页,Apocrine glands,In axillary and genital area,breast,Decapitation secretion,Dependent on sex hormone,Germs grow in moist area,produce body odor,皮肤的构造与功能,第14页,Hairs,Vellus hairs:most skin,attached to tiny muscles in the dermis,“goose bumps”,Terminal hairs:scalp,eyelids,eyebrows,Beard,chest,arm and leg:due to male hormone,Cuticle,cortex,medulla,皮肤的构造与功能,第15页,Blood vessels,Supply the skin and appendages,Regulate body temperature,Sympathetic nerve make it constriction;parasym.nerve,dilatation.,皮肤的构造与功能,第16页,Nerves,Autonomic nerves:vessels,sweat glands,smooth muscles,Sensory nerves,Subepidermal plexus,Merckel plexus,皮肤的构造与功能,第17页,Functions of the epidermis,protecting the body from the environment,particularly the sun,preventing excessive water loss from the body,protecting the body from infection.,皮肤的构造与功能,第18页,Functions of the epidermis-1,ultraviolet radiation create free radicals,protecting the nuclei of the cells in the epidermis and the collagen of the dermis,Part is reflected by the stratum corneum at the skin surface,part is absorbed by the melanin in the epidermal cells,some is scattered within the skin,皮肤的构造与功能,第19页,Functions of the epidermis-2,Water:70-75%of the weight of the basal layer,but only 10-15%of the stratum corneum.,If below 10%,it becomes dry,less flexible and prone to damage,breakdown and infection.,The epidermis as a whole is about 35,m thick when dry,swell to 48,m on full hydration.,皮肤的构造与功能,第20页,Functions of the epidermis-3,Hydration components of Stratum component,1.Keratin,2.a cornified envelope of corneocytes,3.,Lipids,Linoleic acid(diet),ceramides,4,.natural moisturising factors(NMF),Amino acids(40%),pyrrolidone carboxylic acid(12%),lactic acid(12%),urea(8%),salts(18%),unidetified compounds(10%),5.desmosomes,6.enzymes,皮肤的构造与功能,第21页,Functions of the epidermis-4,Three level against invasion by microorganism,Natural layer of oil-in-water emulsion on skin,Stratum corneum,White blood cells in skin,Defense concerns chemicals,Langerhans cells,semipermeable,皮肤的构造与功能,第22页,