Skin and Its Skin and Its AppendagesAppendages

Skin : epidermis,,dermis and its appendages

epidermis

stratum basale

stratum spinosum

stratum granulosum

stratum lucidum

stratum corneum

1. Epidermis1. Epidermis1.11.1 The stratum of epidermisThe stratum of epidermis

stratum basalestratum basale Basal cellBasal cell ： ： cuboidal or columnarcuboidal or columnar ，， stem cell.,stem cell.,

basophilic, rich in desmosomes,basophilic, rich in desmosomes,

undifferentiated cell.(germinal undifferentiated cell.(germinal layer)layer)

stratum spinosumstratum spinosum 4-10-layer prickle cells: 4-10-layer prickle cells: polyhedral, basophilic cytoplasm,rich in desmosomes,polyhedral, basophilic cytoplasm,rich in desmosomes,

abundant in keratin filaments.abundant in keratin filaments.

stratum granulosumstratum granulosum3-5-layer cells: 3-5-layer cells: spindle shapedspindle shaped ，， with degenerative nuclei and organelles;with degenerative nuclei and organelles; basophilic,abundant in granules consisting of keratohyalin;basophilic,abundant in granules consisting of keratohyalin; more keratin filaments.more keratin filaments.

stratum lucidumstratum lucidumtransparent and homogeneoustransparent and homogeneous ，， without nuclei and organelles, without nuclei and organelles,

indistinct cell boundaries. similar with cells of stratum indistinct cell boundaries. similar with cells of stratum corneumcorneum

stratum corneumstratum corneum

Dead cells: Dead cells: withoutwithout nuclei and organelles. nuclei and organelles. with disorganized desmosomes. with disorganized desmosomes. easy to be shed off.easy to be shed off.

1.2 cells of epidermis1.2 cells of epidermis

cells

of

epidermis

keratinocyte

unkeratinocyte

Melanocyte

Langerhans cell

Merkel cell

melanocytemelanocyte

L/M: L/M: lies between basal cells,lies between basal cells,

with thin and long processes which present amongstwith thin and long processes which present amongst

the cells of the stratum basale and stratum spinosum.the cells of the stratum basale and stratum spinosum.

E/ME/M ：：① ① abundant in ribosomes,RER and Golgi abundant in ribosomes,RER and Golgi

complex;complex;

② ② with membrane bound melanosomes.with membrane bound melanosomes.

FunctionFunction ：： protection from the hurt by UV light.protection from the hurt by UV light.

Melanocytes contain melanosomes Melanocytes contain melanosomes which contain tyrosinase .which contain tyrosinase .

tyrosine

Tyrosinase

melanin

albinism

absorb UV

protection

MelanocyteMelanocyte

MelaniMelaninn

granulgranuleses

MelaniMelaninn

granulgranuleses

Langerhans cellLangerhans cell

L/ML/M ：： lies in the superficial layer of stratum spinosumlies in the superficial layer of stratum spinosum

E/ME/M ：： containing characteristic Birbeck containing characteristic Birbeck

bodies which section looks like bodies which section looks like

racket.racket.

Function:Function:antigenantigen presenting cell(APC).presenting cell(APC).

Langerhans cellLangerhans cell

Langerhans cellLangerhans cell

Merkel cellMerkel cell

LL/M/M ：： lie in stratum basalelie in stratum basale ，， flat cell.flat cell.

E/ME/M ： ： related to sensory nerve endings.related to sensory nerve endings.

FunctionFunction ：： related to senserelated to sense

2. dermis2. dermis

dermis

papillary layer

reticular layer

2.1 papillary layer Connective tissue. Abundant in capillaries, free Connective tissue. Abundant in capillaries, free nerve endings and nerve endings and tactile corpusclestactile corpuscles..

2.2 reticular layer dense connective tissues, consisting of bundlesdense connective tissues, consisting of bundles of collagen fibers, numerous elastic fibers, of collagen fibers, numerous elastic fibers,

etc.etc. containing blood vessels, nerve fibers ,containing blood vessels, nerve fibers ,lamellar lamellar corpusclescorpuscles, sweat glands ,etc., sweat glands ,etc. 。。

tactile corpuscle

tactile corpuscle

Lamellar corpuscleLamellar corpuscle

Lamellar corpuscleLamellar corpuscle

Skin

epidermis

dermis

papillary layer

reticular layer

stratum basale

stratum spinosum

stratum granlosum

stratum lucidum

stratum corneum

3. appendages of 3. appendages of skinskin

appendages of skinappendages of skin

3.1 3.1 hairhairHair shaft 、 hair root 、 hair follicle

、hair bulb 、 hair papilla 、 arrector

pili muscle

hair hair shaftshaft

hair hair rootroot

hair hair bulbbulb

hair hair shaftshaft

hair hair rootroot

hair hair bulbbulb

3.2 sebaceous gland3.2 sebaceous gland

Localization: between the hair root and arrector pili muscle

Function: secreting sebum.

sebaceous glandsebaceous gland

sebaceous glandsebaceous gland

3.3 sweat gland3.3 sweat glandTypical sweat glands: merocrine ,

apocrine holocrineFunction: secreting sweat. regulating

body temperature and related to

metabolism.

Atypical sweat glands: apocrine the secretions are viscous,

odourless, and contain proteins

Sweat glandSweat gland

Key pointsKey points

1) composition of the skin:epidermis,dermis 1) composition of the skin:epidermis,dermis and its and its

appendages.appendages.

2) 5 layers of the epidermis, the epidermis: 2) 5 layers of the epidermis, the epidermis:

keratinocyte and unkeratinocyte.keratinocyte and unkeratinocyte.

3) 3 types of the unkeratinocyte and their 3) 3 types of the unkeratinocyte and their functions.functions.

4) 2 kinds of sweat glands and their 4) 2 kinds of sweat glands and their secretions.secretions.