The document discusses the functions of skin, trans epidermal water loss, and cutaneous microflora. The key functions of skin include acting as a permeability barrier, barrier to microorganisms and chemicals, providing mechanical protection, having immunological functions, regulating temperature, protecting from UV radiation, and enabling autonomic and sensory functions. Trans epidermal water loss is influenced by environmental factors, sweat gland activity, and metabolism. It is important for evaluating skin's barrier functioning. Cutaneous microflora includes transient and resident microorganisms that normally inhabit healthy skin and prevent pathogenic colonization through bacterial interference. Factors like dryness, pH, temperature, nutrients, and inhibitory substances influence microfloral growth.

1. FUNCTIONS OF SKIN
TRANS EPIDERMAL WATER
LOSS
CUTANEOUS MICROFLORA
Dr. Swetha Saravanan

2. FUNCTIONS OF
SKIN.

3. FUNCTIONS OF SKIN
1. Permeability barrier.
2. Barrier to microorganisms, chemicals
3. Mechanical barrier
4. Immunlogical functions
5. Temperature Regulation

4. 6. UV Radiation Protection
7. Autonomic & Sensory Function
8. Vitamin D synthesis
9. Sociosexual communication

5. Permeability Barrier
• Epidermis (St. Corneum) – PHYSICAL BARRIER
• Performed - St Corneum , Protein rich cells
embedded in LIPID rich matrix.
• Prevents - polar molecules
• Cant prevent -non polar , slow it.
• Factors- age, environmental changes,skin
continuity

6. Barrier to Microorganisms ; Chemicals
• Sebacceous lipids- Anti – microbial property
• Glycophospholipids, FFA (St. Corneum)- anti
bacterial effect
• AMP’s- broad spectrum anti microbial ,1st line
defence
a. Gram +ve c. Fungi
b. Gram –ve d. Virus
• AMP’s- produced in regions of hair follicle &
sweat glands

7. AMP (a) In normal skin, small amounts of AMPs are produced by
the epidermis and are concentrated around hair follicles and in
sweat glands. (b) After injury or infection, keratinocytes increase
synthesis of AMPs and further AMPs are produced by neutrophils
that are recruited as part of the acute inflammatory response.

8. Mechanical Barrier
• Skin- compressed , elastic
• Presence of ground substance, collagen,
elastic fibres
• Influenced by hydration , humidity.
• These properties prevent injury due to blunt
objects, pressure.

9. Immunological Functions
• Epidermis- Keratinocytes , Langerhans cells
• Dermis- T Lymphocytes
• Sweat glands & oil glands secretion-
a. Sweat – Inc. pH, salt,lysozyme,
AMP’s – 1st line of defence
b. Lipids

10. • Recognition of exogenous antigens, elicitation
of antigen- specific cell responses.
• Immune dysfunction –
Immunobullous disorders
Allergic contact dermatitis
Atopic dermatitis
Psoriasis
Mycosis fungoides.

11. TEMPERATURE REGULATION:
• Sensory input –thermoregulation
• Functions to permit heat loss/ reservation
• Thermoreceptor cells Hypothalamus
 inhibition of sweating( eccrine glands)
or stimulation of shivering

13. • Blood supply of dermis – important for
temperature regulation
• A-V shunt system- enables the blood flow
to an extensive ,superficial venous plexus
• More at the feet, hand ,lips ,nose ,ear.

14. UV Radiation
UVA- epidermis -
sunburn, premature
ageing of skin, skin
cancer.
UVB- deeper dermis-
Chronic sun damage,
ageing and cancer
development

15. • Barrier Mechanisms-
1. Melanin production in epidermis
2. Protein barrier in the stratum Corneum.
• MOA-
Absorbing the radiation & minimizes DNA
& its other cellular constituents absorption
(lipids, urocanic acid)

16. Sensory & Autonomic functions
• Dense, 3-D network of highly specialized
afferent sensory , efferent autonomic nerve
branches.
• Detects- touch , vibration, pressure,
temperature changes , pain & itch.
• Glabrous , hairy skin - different types of
mechanoreceptors.

17. Superficial- Different types for glabrous & non
glabrous hair –small receptive field.
Deep- Same for both – large receptive field.

19. • Thermal sensation
Corresponding receptors for warmth &
cold sensation
• Mechanical Sensation
Mechanical nociceptors are present.

20. Vitamin D synthesis
• Synthesized in
skin.
• Essential for bone
metabolism.

21. Sociosexual communication
• Provides visual appeal, smell, feel.
• Important role in social, sexual
communication.
• Skin, hair, nails- decorative value.
• Cosmetics & clothes enhance appearance.

22. TRANS EPIDERMAL
WATER LOSS.
(TEWL)

23. • TEWL is the water loss through intact SC.
Not through sweat glands
Not through follicles.

24. DAMAGED
SKIN

25. Takes place – diffusion, evaporation.
In mammals – insensible water loss –
little physiological control.
Identify skin damage (chemicals, burns,
path causes, physiological causes)
TEWL proportional DAMAGE .

26. FACTORS INFLUENCING
Environmental factors- humidity,
temperature, seasonal variation.
Sweat gland activity
Metabolic activity.

27. TEWL – important for evaluating barrier
functioning.
TEWL measurements –discover disturbances -
skin protective function.
Typical fields- allergic tests, supervision the
healing process of skin damages & burns,
testing the effectiveness & biocompatibility of
cosmetic products.

28. CUTANEOUS MICRO
FLORA

29. WHAT’S CUTANEOUS MICRO
FLORA?
• Microorganisms that are commonly found on
OR in the body sites of an healthy person.
• Acc. to estimate- 10 10 bacteria.
• Based on type of skin- micro flora varies.

30. • Prevent colonisation – pathogens & possible
disease – bacterial interference.
Competitive binding receptors sites on
host cells –
• Nutrition.
• Mutual inhibition by metabolic or
toxic products or antibiotics
materials.

32. RESIDENT:
1. Presents invariably/months in a
particular site
2. Reduced by washing but not eleminated
3. If disturbed- transient flora – colonises
 INFECTION

33. TRANSIENT:
1. Present briefly, rest on body surface but
do not persist.
2. Eliminated on washing.
3. Little significance- normal resident is
intact.

35. Normal flora is not static, constant
change
Depends on :
1. Age
2. Nutritional status of the site
3. Disease state
4. Drug or antibiotic effects
5. pH
6. Oxidation – reduction potentials

36. DISTURBED BALANCE
Lead to INFECTION

37. MICROBIAL DISEASE OF THE
SKIN MAY RESULT FROM:
• Breach of intact skin.
• Skin manifestation of systemic
disease.
• Toxin mediated skin damage.

38. Factors Influencing Flora Growth:
• Dryness
• pH
• Temperature
• Presence of nutrients
• Presence of inhibitory substance

39. DRYNESS
1. Inhibits micro-bacterial growth.
2. Dryness – bacteria enter dormant state or
die.
3. Moisture area – Large population
( axilla, perineum ,between toe’s & scalp).

40. LOW pH
• Skin -3 – 5pH
• Low pH inhibits growth for many kinds of
organisms
INHIBITORY SUBSTANCE
• Several bactericidal or bacteriostatic present
in normal skin
• Sweat gland secrete lysozyme & enzyme –
destroys peptidoglycan of bacteria wall.

41. DIRECT ENTRY INTO SKIN OF BACTERIA AND FUNGI
STRUCTURE INVOLVED INFECTION COMMON CAUSE

42. NAIL FLORA
• Similar to skin.
• Additionally, dust & extra material – trapped.
• Commonly-
1. Aspergillus
2. Penicillium
3. Cladosporium
4. Mucor

43. ADVANTAGES OF NORMAL FLORA
• Skin bacteria produces fatty acid -
discourages other species.
• De-squamination of epithelium.

44. DISADVANTAGE
• Organisms from perianal region ascend
the urethra  Urinary tract Infection.

46. SUMMARY
FUNCTIONS OF SKIN.
• Permeability barrier.
• Barrier to microorganisms, chemicals
• Mechanical barrier.
• Immunological functions.

47. • Temperature Regulation.
• UV Radiation Protection.
• Autonomic & Sensory Function.
• Vitamin D synthesis.
• Sociosexual communication.

48. TRANS EPIDERMAL WATER LOSS
• TEWL is the water loss through intact
SC.
• FACTORS INFLUENCING-
1. Environmental factors- humidity,
temperature, seasonal variation.
2. Sweat gland activity
3. Metabolic activity.

49. • Evaluating barrier functioning.
• Typical fields-
Allergic tests,supervision the healing process of
skin damages & burns, testing the effectiveness
& biocompatibility of cosmetic products.

50. CUTANEOUS MICRO FLORA.
• Microorganisms that are commonly found on OR
in the body sites of an healthy person.
• Prevent colonisation – pathogens & possible
disease – bacterial interference.
• Normal flora - transient or resident.
• Its is not static, constant change.
• Microbial disease of the skin may result …..

51. Factors Influencing Flora Growth:
• Dryness
• pH
• Temperature
• Presence of nutrients
• Presence of inhibitory substance

52. • NAIL flora – similar to skin,Additionally – dust
is trapped.(APCM)
• ADVANTAGES- Discourages other species,
desquamination.
• DISADVANTAGES-Organisms in perianal
region- UTI.