Chapter 11 Skin skin is the largest organ of the body, constitutes about 16% of body weight its total surface area is about 1.2-2.2 m2 function: protection, sensory reception, excretion and thermoregulation
Chapter 11 Skin ---skin is the largest organ of the body, it constitutes about 16% of body weight ---its total surface area is about 1.2-2.2 m2 ---function: protection, sensory reception, excretion and thermoregulation
Structure of skin epidermis 角质层 汗腺导管 透明层 dermis 颗粒层 基底层 乳头层 一小动脉 网织层 汗腺导管 Eeg 小静脉 汗深分部 神轻 环以小体 一皮下绀
1. Structure of skin ---epidermis ---dermis
1) epidermis keratinised stratified squamous epithelium consist of keratinised cell and non- keratinised cell
1) epidermis ---keratinised stratified squamous epithelium ---consist of keratinised cell and nonkeratinised cell
① keratinised ce from basal to 角化细胞随 SurTace we can 透明角质颗粒 排入细胞间隙的 板层颗粒内容物 颗粒层细胞 classify the cells 板层颗粒 into five layers 签总一 吞入的黑素颗粒 黑素颗粒 基底细胞 黑素体 lion 黑素细胞 半桥粒 基膜
①keratinised cell: ---from basal to surface, we can classify the cells into five layers
a stratum basale -structure LM: -a layer of cuboidal or low columnar cell with a large, pale N basophilic cytoplasm EM: -free ribosome -keratin filament- tonofilament -desmosome -function: mitotic activity and proliferation
a. stratum basale ---structure: LM: -a layer of cuboidal or low columnar cell with a large, pale N -basophilic cytoplasm EM: -free ribosome -keratin filament- tonofilament -desmosome ---function: mitotic activity and proliferation
b, stratum spinosum structure LM,=4-10 layers polygonal cell with large round nucleus spinous processes slight basophilic cytoplasm EM: -tonofibrils lamellated granules /100-300nm membrane-coated /contain phospholipid and steroid intercellular bridges- Desmosome
b. stratum spinosum ---structure: LM: -4-10 layers polygonal cell with large round nucleus -spinous processes -slight basophilic cytoplasm EM: -tonofibrils -lamellated granules: /100-300nm membrane-coated /contain phospholipid and steroid -intercellular bridges- Desmosome
C Stratum granulosum -structure LM:-3-5 layers flattened cell - muclei begin to degenerate-stained slightly keratohyalin granules: basophilic EM: -keratohyalin granules: With tonofilament insert into them -lamellated granules: fused with cell membrane keratohyalin tonofilament keratin
c. stratum granulosum ---structure: LM: -3-5 layers flattened cell -muclei begin to degenerate-stained slightly -keratohyalin granules: basophilic EM: -keratohyalin granules: with tonofilament insert into them -lamellated granules: fused with cell membrane * keratohyalin + tonofilament = keratin
d stratum lucidum structure LM 3-4 layers of cell appear homogeneous and transparent -no nucleus and organella -eosinophilic-keratohyalin tonofilament embedded in homogeneous matrix
d. stratum lucidum ---structure: LM: -3-4 layers of cell appear homogeneous and transparent -no nucleus and organella -eosinophilic-keratohyalin -tonofilament embedded in homogeneous matrix
e stratum corneum -structure LM,-several layers horny cell -died cell- no nucleus and organella -eosinophilic -keratin x desquamation: surface keratin will shed from outer surface
e. stratum corneum ---structure: LM: -several layers horny cell -died cell- no nucleus and organella -eosinophilic -keratin * desquamation: surface keratin will shed from outer surface
e non-keratinised cell a, melanocyte structure LM, -large cell with long branches -located among stratum basale cells EM, -ribosome RE R Golgi complexes osine melanosome( tyrosinase)→↓ melanin melanin granules
② non-keratinised cell: a. melanocyte: ---structure: LM: -large cell with long branches -located among stratum basale cells EM: -risosome -RER -Golgi complexes tyrosine -melanosome(tyrosinase) →↓ ↓ melanin melanin granules