Transcript 皮肤的解剖和功能

Anatomy and
Function of Skin
Importance of the study
of skin diseases
 Common
and prevalent diseases
 skin beauty and health care
 reflection of the body health
（paraneoplastic skin diseases)
 Sex Transmitted Disease(STD)
，AIDS
I、Introduction
 Skin
- the biggest organ of the
human body
 Composition of the skin
 Origin of the skin
 Physiologic function of the
skin
 Immune system of the skin
1.Skin-biggest organ
human body
of
the
Three layers of the skin- epidermis, dermis,
and subcutaneous tissue. It’s contiguous with
the environment. The skin protects human
body against exogenous harmful factors and
maintains the homeostasis of the inner
environment.
2．Composition of the skin
 epidermis
 dermis
 subcutaneous tissue
blood vessel, lymphatics, nerve ending, apocrine
gland, eccrine gland, sebaceous gland, hair
follicle, nail, et al
3．Origin of the skin
• epithelial structures(epidermis, hair follicle,
sebaceous gland, apocrine unit, eccrine sweat unit
and nail) are derived from ectodermal.
• melanocyte, nerve and special sensor are derived
from neural crest.
• dermis, subcutaneous tissue, lymphatics, blood
vessel, Langerhans’ cell, mast cell, fibroblast and
lipocyte are derived from mesodermal.
4．Physical function of the
skin
protection, secretion,
discharge, absorption,
thermoregulation, sense
5．Immune system of the skin
•Regulation of immune response: cell
elements and molecular elements
•Immunosurveillance
•Immune tolerance and rejection
II、Epidermis
keratinocyte
melanocyte
non-keratinocyte
Langerhans’ cell
Merkel cell
keratinocyte
Producing keratin
+
non-keratinocyte
─
tonofilament
in the cytoplasm
+
─
desmosome
+
─
Dendritic-shaped cell
─
+
keratinocytes
1．stratum basalum,basal cell layer
2． stratum spinosum,prickle cell layer
3． stratum granulosum,granular layer
4． stratum lucidum
5．stratum corneum,horny layer
Function of the keratinocyte：
⑴
Continuously producing keratin and
forming horny layer to protect against
various chemical and physical factors
⑵
participating immune response in the
skin
⑶
secreting cytokines and helping to
activate T lymphocytes
desmosome：
attachment plates between adjacent
keratinocytes in basal layer and prickle layer
Desmosome transmembrane protein
desmoglein,DG
desmocollin,DC
•Desmosome cytoplasm plakin
• desmoplakin,DP
plakoglobulin,PG
Basement membrane zone
plasma membrane
lamina lucida
basal lamina
reticular lamina
non-keratinocytes
• melanocyte
•
Langerhans cell, Lc
•
Merkel cell
•
indeterminate cells
1．melonocyte
•epidermal melanin unit
melanocytes are derived from the nerual
crest and reside in the basal layer. Melanocytes
are dendritic cells and contain large number of
melanosomes. Any one melanocyte is contact
with 30-40 keratinocytes through its dendrites,
form the so-called epidermal melanin unit.
•Protective barrier against UV
2．The Langerhans’ cell
Langerhans’ cells are originate in bone marrow
• They exist in the epidermis above the basal
layer without keratin filament or desmosomes.
They are characterized by a folded nucleus and
distinct intracytoplasmic organelles called
Birbeck granules，resembling a tennis racquet.
• recognition, uptake, processing, and
presentation of antigens to sensitized T
lymphocytes.
朗
格
汉
斯
颗
粒
3．Merkel cell
a kind of neurosecretory cell, located
directly above the basement
membrane and closely associated
with neurites, so called Merkel cellaxon complex.
4．Indeterminate cell
They are dendritic cells
without melanosomes and
Birbeck granules，but have
positive reaction to OKT6.
III、Dermis
•collagen
•elastic fiber
•reticulum fiber
•cell(fibroblast、histocyte、mast
cell)
•matrix
IV、Subcutaneous fat tissue
It’s composed of loosen
connective tissue and lobules of
lipocytes.
V、Appendages
1．eccrine gland
2．apocrine gland
3．sebaceous gland
4．hair follicle
5．nail
1． eccrine gland：
• Distribution
They are found at virtually all skin
sites except at the following sites: border
of the lip, nympha, phallus, glans, flexion
side of prepuce and nail beds, and most
abundant on the palms, soles and axillae.
They reach to skin surface directly.
•Composition of the eccrine gland:
•Coil gland is composed of a single layer of cells
with two types: pale cell and darker-staining cell
and regulated by cholinergic nerve.
The duct is composed of a double layer of
basophilic epithelial cells and divided into
intraepidermal component and intradermal
component.
•Function of the eccrine gland：
⑴dissipate excessive body heat
⑵soften horniness
⑶acidify sweat
⑷take place of partial renal
function
⑸emulsify lipid
⑹secrete immunoglobulin
2．apocrine gland：
generally confined to axillae,
areolae,the anogenital region.It
reaches the hair follicle
instead of the skin surface.
3．sebaceous gland：
•Distribute throughout all skin sites
except palms and soles，greatest abundant
on scalp, face,middle part of the body and
vulvae.
•Always associated with upper portion of
the hair follicles
•Reach skin surface,such as vermilion
border of the lip(Fordyce’s spots）,
areolas(Montgomery’s tubercles),
prepuce(Tyson’s glands) and
Influence factors:
•age,sex,race
•temperature
•hormone
•humidity
•anatomical site
•nutrition factor
lipase of P.acnes or P. ovale in
the sebaceous gland acts on the
sebum to produce free fatty
acids which stimulate
inflammatory reactions of hair
follicles and surrounded tissue
to form folliculitis.
Function of the sebum
⑴emulsify water
⑵constituents of vitamin D
⑶acidification
⑷emulsify lipid
4．hair：
classification：
•long hair（armpit hair,
scalp hair, pubic hair）
•short hair（eyebrow,
eyelashes,vibrissa）
•毳毛
Composition of the hair
•hair shaft
•hair root
•hair bulb
transection of the hair
•medulla
•cortex
•hair cuticle
hair follicle：
•inner root sheath
•outer root sheath
•connective tissue sheath
hair bulb：dermal components in the
fundus of hair follicle
5．nail：
• perionychial area
• nail bed
• nail plate
VI、Blood vessels and lymphatics
and nerves of skin