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
1,Structure of skin
---epidermis
---dermis
1) epidermis
---keratinised stratified squamous epithelium
---consist of keratinised cell and non-
keratinised cell
① keratinised 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
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
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
* desquamation,surface keratin will shed from
outer surface
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
---function:
? responsible for skin color
? absorb ultraviolet light
? protect deep tissue
b,Langerhans cell
---structure:
LM,-deep nucleus,light cytoplasms
-among the spinous cell
-dendritic-typed processes
EM,-lysosome
-Birbeck granule:
/membrane-coated
/15-30 nm long,4 nm in D
---function:
? antigen presenting cell in skin
? involve in immune reaction
c,Merkel’s cell
---structure:
? located in basal layer
? with short processes
? contain many dense-core granules
? chemical synapse,between Merkel’s cell
and afferent N
---function,not very clear,may be
? sensory epithelial cell
? neuroendocrine cell ( APUD,amine
precursor uptake and decarboxylation cell)
2) Dermis,DCT
---papillary layer,dermal papillae-increase
the junction between epi,and
underlying CT
? capillary papillae
? nervous papillae
---reticular layer:
DCT,contains rough F-CF,EF,RF
? large BV,LV
? NE,lamellar corpuscle
? skin appendages,including sweat gland,
sebaceous gland and hair
2,hypodermis,LCT and fat tissue
3,skin appendages
1) hair
2) sebaceous gland
3) sweat glands
---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
1,Structure of skin
---epidermis
---dermis
1) epidermis
---keratinised stratified squamous epithelium
---consist of keratinised cell and non-
keratinised cell
① keratinised 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
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
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
* desquamation,surface keratin will shed from
outer surface
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
---function:
? responsible for skin color
? absorb ultraviolet light
? protect deep tissue
b,Langerhans cell
---structure:
LM,-deep nucleus,light cytoplasms
-among the spinous cell
-dendritic-typed processes
EM,-lysosome
-Birbeck granule:
/membrane-coated
/15-30 nm long,4 nm in D
---function:
? antigen presenting cell in skin
? involve in immune reaction
c,Merkel’s cell
---structure:
? located in basal layer
? with short processes
? contain many dense-core granules
? chemical synapse,between Merkel’s cell
and afferent N
---function,not very clear,may be
? sensory epithelial cell
? neuroendocrine cell ( APUD,amine
precursor uptake and decarboxylation cell)
2) Dermis,DCT
---papillary layer,dermal papillae-increase
the junction between epi,and
underlying CT
? capillary papillae
? nervous papillae
---reticular layer:
DCT,contains rough F-CF,EF,RF
? large BV,LV
? NE,lamellar corpuscle
? skin appendages,including sweat gland,
sebaceous gland and hair
2,hypodermis,LCT and fat tissue
3,skin appendages
1) hair
2) sebaceous gland
3) sweat glands
