handout fisiologi kulit
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SKINPHYSIOLOGYDr. Trinovita Andraini, Mbiomed
Dr. Imelda Rosalyn Sianipar, MBiomed
Department of physiology, FMUI
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OUTLINE
Introduction of the integumentary system
Function of the skin
Effect of the environment to the skin health
Relation of the integumentary system with othersystem
2
THE INTEGUMENTARY SYSTEM
Integumentary System
(inte = whole; -gument = body covering )
Two major components:
Cutaneous membrane / skin
Accessory structure: hair, nails, & multicellular exocrine
glands
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SKIN(CUTANEOUS MEMBRANE)
Largest organ of the body, both surface area &
weight
In adults,
covers an area of about 2m2
weighs 4.55 kg (16% of total body weight)
Has 2 components: Epidermis
Dermis
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SKIN(CUTANEOUS MEMBRANE)
The epidermisis the ectodermally derived
outer layer composed of keratinized stratified
squamous epithelium.
The dermisis the mesodermally derived
layer of dense irregular collagenous
connective tissue that underlies and
interdigitates with the epidermis.
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Skin Structure
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ACCESSORY SKIN STRUCTURES
1. Hair and hair follicles
2. Smooth muscle arrector pilli
3. Cutaneous glands
4. Nails
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HAIR AND HAIR
FOLLICLE
- Has minor protective
function
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GLANDS OF THE SKIN
Major glands:
Exocrine glands
Consist of:
1. Sebaceous glands(oil)
2. Sweat glands
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GLANDS IN THE SKIN
Skin2 types of exocrine glands:
Sebaceous glandsand sweat glands
Sebaceous (oil) glandsoily lipidsecretionsebuminhibits bacteriagrowth, lubricates and protects thekeratin of the hair shaft and conditionsthe surrounding skin.
Sebaceous follicles (not associated withhair follicles) discharge sebum directlyonto the epidermis: on the face, back,chest, nipples and external genitalia
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GLANDS IN THE SKIN
Sweat glands/ sudoriferous glands:
apocrine sweat glands and merocrine
sweat glands.
Apocrine sweat gland
- Armpits; around the nipples and pubic region
- Secretion: sticky, cloudy and odorous
- Secreting at pubertynutrient source for
bacteria
- Controlled by nervous system and circulating
hormones11
GLANDS IN THE SKIN
Merocrine (Eccrine) sweat glands
- More numerous than apocrine (adult : 2-5 million) palms, soles and forehead >>
- Sweat produced = sensible perspiration
- 99% water + electrolites (NaCl), organic
nutrients, peptide (AntiBiotikproperties),waste products.
pH 4.0 -6.8
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GLANDS IN THE SKIN
Functions of merocrine sweat glands
- Cooling the surface of the skin
- Regulated by neural and hormonal
- Excreting water and electrolytes (+
ingested drugs)
- protection from Environmental Hazards
* Dilution harmful chemicals; inhibition growth
of microorganisms by flushing and action ofdermicidin
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GENERALFUNCTIONOFTHEINTEGUMENTARYSYSTEM
ProtectionExcretion
andAbsorption
SensationMaintenance
of BodyTemperature
Synthesis ofVitamin D3
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GENERAL FUNCTION
B. Excretion and Absorption
- Sweat excretion
- Absorption of water soluble substances,
certain lipid soluble materials, certain
drugs and gases
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GENERAL FUNCTION
C. Sensation of touch, pressure, pain
and temperature stimuli
Variety of nerve endings and sensory
receptors are distributed in the
epidermis and dermis
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GENERAL FUNCTION
D. Maintenance of body temperature
- Thermoreceptors
- Sweat production and evaporation
- Alterations in cutaneous blood flow
conserve or release heat
* Local control
* Neural control (primary
determining factor)
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GENERAL FUNCTIONMAINTENANCEOFBODYTEMPERATURE
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GENERAL FUNCTION
E. Synthesis of vitamin D3
- Action of UV rays in sunlight to the molecule inthe skin.
- The role of liver and kidneys to produce the
most active form of vitamin D3
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SYNTHESISOFVITAMIND3
Guyton&Hall. 2011
7 dehydrocholesterol
(in the skin)
Cholecalciferol (Vit. D3)
UV Radiation
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PROTECTIONFUNCTIONOFTHESKIN
The chief function of the skinto form a barrier between
the external environment and the internal milieu of the
host
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SKIN
HOSTILEEXTERNAL
ENVIRONMENT
INTERNALMILIEU OF THE
HOST
PROTECTIONFUNCTIONOFTHESKIN
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The skin barrier prevents exessive water loss (inside-outside barrier) and entry of harmful substance from
the environment (outside-inside barrier)
Fitzpatrick Dermatology, 2008
Factors that play role in the protectionfunction of the skin: Stratum corneum
natural moisturizing factors (NMF) in the skin
Oily sebum
Pigment melaninprotection to UV radiation
Acidic pH of perspiration
Epidermal langerhans cells and macrofages in thedermis
Production of antimocrobial peptides (AMPs) byviable cell in epidermis 23
STRATUMCORNEUM
Localized in the outerepidermal layer
The thickness is 10-20 um
Is composed of:
Corneocytes, which are arranged in a scaffold-like
lattice, bound together by involucrin
Extracellular lipid matrix
water impermeability
The impermeability of water of the skin is 1000
times higher than that of other membranes of
living organisms24
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EPIDERMIS
Epidermis is terminally differentiated stratified
squamous epithelium
The mayor cell type is keratinocyte.
Consist of: Stratum basale, stratum spinosum,
stratum granulosum, stratum corneum
Epidermis is in a constant state of self replacement
Keratinizationis the transformation process ofstratum basale cells into stratum corneum cells
The time from cell division to shedding from the
stratum corneum: 28 days
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EPIDERMALLAYER
26
Fitzpatrick Dermatology, 2008
KERATINIZATION
27
At the stratum basale, keratinocytes stem cells devideinto daughter cells, which are displaced outward
Keratinocytes differentiate through successive overlyinglayers to enter the stratum corneum
During differentiation, keratinocyte on the Stratumspinosum and granulosum generate lamellar bodiescontaining lipid
During the terminal differentiation, lipid matriks from
lamellar bodies spread over to the intercellular domainsof stratum corneum and form a bilayer stucture
Keratinocytes die, apoptosis and their cellular organelles,nuclei and cytoplasm disappearcorneocytes
The cells appear flatened and the keratin filaments(involucrin) align the corneocytes into disulphide crosslinked macrofibres.
KERATINIZATION
28
Denda. Skin barrier function as a self-organizing system. Forma, 2000. 15:227232
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EXTRACELLULARLIPIDMATRIXINSTRATUMCORNEUM
Consist of:
50% Ceramides
25% cholesterol
15% free fatty acid
Phospholipid
This lipid is secreted from lamellar bodies (which
found in keratinocyte at spinosum/granulosum
layer).
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FORMATIONOFTHEEXTRACELLULARLIPID
MATRIXONSTRATUMCORNEUM
30
Feingold. The role of epidermal lipids in cutaneous permeability barrier homeostasis. J. Lipid Res. 2007. 48: 25312546.
EXTRACELLULARLIPIDMATRIXMEDIATE
PERMEABILITYBARRIERFUNCTION
provide an impermeable barrier for the passage of
water out of the stratum corneum and the
prevention of the natural moisturizing factors
(NMF) from leaching out of the surface layers ofskin.
Ceramidestrap water molecules in their
hydrophilic (water attracting) region
Glycerol (from breakdown of phospholipid byPLA2)water holding agentkeep stratum
corneum hydratedcrucial for smooth and flexible
skin 31
EXTRACELLULARLIPIDMATRIXMEDIATE
PERMEABILITYBARRIERFUNCTION
Cholesterol: plays an important role in regulating
desquamation
FFAacidification of the stratum corneum (pH 5-
5,5)important for enzymes activities, eg. Beta
glucocerebrosidase and acidic sphyngomyelinase
If ph >
Beta glucocerebrosidase activities is reducedthe
processing to form ceramide is impairedabnormalities
of extracellular lipid membranesdecreased
permeability barrier function
activities of protease increasescorneosytes desquamation
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AFFECTOFENVIRONMENTTOSKINBARRIERSKINBARRIERHOMEOSTASIS
Skin barrier function has ability to adapt to theenvironmentsense the environment changeand reorganizes its function to adapt the newenvironment
Low humidity, mechanical assault, chemicalassault (eg. treatment with an organic solvent ordetergent) stratum corneum barrier functiondemagehomeostasis process accelerated:
Lipid synthesis
Lipid processing
Acceleration of exocitosis of lamellar bodies
Barriers recovers to its original level 33
REGULATIONOFPERMEABILITYBARRIERREPAIR
Calcium gradient
In normal condition, there is high level extracellular
calcium in the upper epidermis surrounding the
stratum granulosum cells
After barrier disruptionincrease water movement
through the compromised stratum corneum carries
calcium outward toward the skin surfacereduction
calcium concentrationprimary signal to induce
lamelar bodies secretion
Cytokines: IL-1, IL-6, TNF alfarapidly release
after barrier disruptionregulating permeability
barrier34
REGULATIONOFPERMEABILITY
BARRIERREPAIR
35
Feingold. The role of epidermal lipids in cutaneous permeability barrier homeostasis. J. Lipid Res. 2007. 48: 25312546.
EFFECTOFENVIRONMENTTONATURAL
MOISTURIZING FACTORS(NMF) INTHESKIN
natural moisturizing factors (NMF) are present
in the stratum corneum:
free amino acids
Other physiological chemicals such as lactic acid,
urea and salts
are responsible for keeping the skin moist and
pliable by attracting and holding water
The water content of the stratum corneum is
normally about 30%.
In the stratum corneum there are also protein
fillagrin which can degradate to amino acid36
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EFFECTOFENVIRONMENTTONATURAL
MOISTURIZINGFACTORS(NMF) INTHESKIN
In dry weatherthe skin is dryThe proteolytic
enzyme is activated to breakdown filaggrinprotein to amino acidsamino acid is NMF
which control the osmotic pressure of the skinand the amount of water it holds.
There is less need for breakdown of filaggrin in
humid weather than in dry weather
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DESQUAMATION
Desquamation is another important factor in keepingthe skin smooth.
Desquamation is the enzymatic process of dissolving
the desmosomes, the protein connections betweencorneocytes, and the eventual shedding of these cells.
There is a normal physiological balance in theproduction of corneoctyes and shedding.
The proteolytic enzymes responsible for desquamationfunction in the presence of a well-hydrated stratum
corneum. These enzymes are located intercellularly.
In the absence of water, the cells do not desquamatenormally and the result is thickened, dry, rough, scaly
skin.39
DESQUAMATION
40
Intact corneocytes in upper level of
hydrated stratum corneum
Proteolytic enzymes break proteinconnections between corneocytes
Corneocytes desquamate
Skin stays normal without dry scales
EXTERNALFACTORTHATDAMAGESKIN
Environmental low humidity
Exposure of irritating chemical (solvents,detergents, excessive use of water and soap)
Damage skin barrier, interrupting the lipid
bilayers, removing natural moisturizing factors
loss of water from the stratum corneumdesquamation is not normal
skin is dry and rough
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EFFECTOFULTRAVIOLETRADIATIONONTHESKIN
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Fitzpatrick Dermatology, 2008
EFFECTOFULTRAVIOLETRADIATIONONTHESKIN
UV radiation
UV C (290-200 nm)/Germicidal radiation
Strongly absorbed by DNAlethal for viable cell
Potent mutagenMay contribute to the skin cancer
completely Filtered out by the ozone layer.
UV B (315-290 nm)/sunburn spectrum
2-5% of UV radiation, highest when the sun is directly overthe head
UV A (400-315 nm)
95-98% of UV radiation
UV A I (340-400)
UV A II (320-340)
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PHOTOBIOLOGICALRESPONSE
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Fitzpatrick Dermatology, 2008
EFFECTOFULTRAVIOLETRADIATIONON
THESKIN
1. Acute effectshort live and reversible
Tanning response (pigmentation)protective
against subsequent exposures
Erythema
Injury to langerhans cell and keratinocyte
2. Chronic Effect
Photoaging
Skin cancer
3. Other effect: Synthesis of vit D3
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TANNINGRESPONSE/PIGMENTATION
Pigmentation, the synthesis & distribution of
melanin in the epidermis
Melanin:
Produced byMelanocytes
Production determine by genetic factors, exposure to
light, and hormones
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MELANOCYTES
Irregulary shaped cells with many long processes that
extend between the keratinocytes of the stratum basale
and the stratum spinosum
There is approximately 1 melanocytes per 5-6 basal
keratinocytes
Produce melanin which is stored into melanosomes that
are transfered to keratinocytes through the melanocytes
dendrites prosesses
Signals from keratinocytes regulates melanocytes
survival, dendricity and melanogenesis
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MELANIZATION
Involves several steps:
1. Transcription of protein required formelanogenesis
2. Melanosomes biogenesis
3. Sorting melanogenic protein into melanosomesmelanin biosintesis in the melanosomes
4. Transport of melanosomes into the tips ofmelanocytes
5. Transport of melanosomes into the
keratinocytes
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MELANINBIOSINTHESIS
49
Eumelanin
Fitzpatrick Dermatology, 2008
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MELANINTRANSFERFROMMELANOCYTETOKERATINOCYTES
1. Melanosomes are produced by the golgiapparatus of the melanocyte
2. Melanosomes move into melanocyte cell
processes
3. Epithelial cells phagocytize the tips of themelanocyte cell processes
4. The melanosomes, which were produced inside
the melanocytes, have been transferred toepithelial cells and are now inside them
Tate P. Principles of Anatomy and Physiology;McGrawHill. 2009
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cutaneous pigmentation does not depend on
the melanocyte number, but rather on:
melanogenic activity within melanocytes
the proportion of mature melanosomes,
and their transfer/distribution within the
keratinocytes
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EFFECTUV RADIATIONONTANNING
Induce immediate tanning and delayed tanning
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PHOTOAGING
Dry, deeple wrinkled, inelastic, irregularities in
pigmentation
UV radiation cause degenerative changes in
elastin and collagenaccumulate over time and
are largely irreversible
The end result: degradation of type I collagenfibrils and disorganization and degeneration of
dermal connective tissue
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SKINCANCER
UVB
Generation of ROS
Damages melanin
Damages DNA: formation of pyrimidine dimers
between adjacent pyrimidines on the same DNA
strand
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RELATIONS OF THE INTEGUMENTARYSYSTEM
WITH OTHER SYSTEM IN THE BODY
MUSCULOSKELETAL SYSTEM Synthesizes vitamin D3, essential for:
Calcium & Phosphorus absorption (bonemaintenance and growth)
Calcium absorption (muscle contraction)
Contraction of skeletal muscles pull against skin offace, producing facial expressions, important incomunication
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NERVOUS SYSTEM
Nerve endings in skin and subcutaneous tissue
provide input to the brain for touch, pressure,
thermal and pain sensations
Control blood flow and sweat gland activity for
thermoregulation
Stimulates contraction of arrector pili muscles to
elevate hair
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ENDOCRINE SYSTEM
Keratinocytes in skin help activate vitamin D tocalcitriol, a hormone that aids absorption of dietarycalcium and phosphorus
Sex hormones
Stimulate sebaceous gland activity
Influence growth, distribution of subcutaneous fat,and apocrine sweat gland activity
Adrenal hormone
Alter dermal blood flow and help mobilize lipidsfrom adipocytes
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CARDIOVASCULAR SYSTEM
Local chemical changes in dermis cause wideningand narrowing of skin blood vessels, which helpadjust blood flow to the skin
Provides oxygen and nutrients; delivers hormonesand cells of immune system
Carries away carbon dioxide, waste products andtoxins
Provides heat to maintain normal skin temperature
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LYMPHATIC SYSTEM &IMMUNITY
Discourage penetration and growth of microbes: Provide mechanical barriers
Langerhans cells in epidermis : recognizing & processingforeign antigens
Macrophages in the dermis : phagocytize microbes thatpenetrate the skin surface
Mast cells trigger inflammation and initiate the immuneresponse
Defending the integument by providingadditional macrophages and mobilizinglymphocytes 59
RESPIRATORY SYSTEM
Hairs in nose filter dust particles from inhaledair
Stimulation of pain nerve endings in skin mayalter breathing rate
Provide oxygen and eliminates carbon dioxide
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DIGESTIVE SYSTEM
Helps activate vitamin D to the hormonecalcitriol, which promotes absorption of dietarycalcium and phosphorus in the small intestine
Provides nutrients for all cells and lipids forstorage by adipocytes
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URINARY SYSTEM
Assists in excretion of water and solutes
Keratinized epidermis limits fluid loss throughskin
Excretes waste products
Maintains normal pH and ion composition of
body fluids
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REPRODUCTIVE SYSTEM
Nerve endings in skin and subcutaneous tissue respondto erotic stimulicontributing to sexual pleasure
Mammary glands (modified sweat glands) produce milk
Suckling of a baby stimulates nerve endings in skinleading to milk ejection
Skin stretches during pregnancy as fetus enlarges
Sex hormones affect hair distribution, adipose tissuedistribution in subcutaneous layer, and mammary glanddevelopment
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REFERENCES
Tortora GJ. Principles of anatomy and physiology. 11thed;
John Wiley: 2006
Tate P. Principles of anatomy and physiology. McGrawHill.
2009
Feingold. The role of epidermal lipids in cutaneous
permeability barrier homeostasis. J. Lipid Res. 2007. 48:25312546.
Denda. Skin barrier function as a self-organizing system.Forma, 2000. 15:227232
Wolff K, Goldsmith L, Katz S, Gilchrest B, Paller A, LeffellD. Fitzpatrics dermatology in general medicine. 7 ed.Mc.GrawHill. 2008
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hank you65
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