1. Anatomical basis of
cutaneous
structure & function
Speaker - Dr. Dibbendhu Khanra
Chairperson – Dr./ Prof. D. Bandopadhyay

2. Bob Marley died of malignant melanoma

3. Paris
Hilton
has
atopic
dermatitis,
suffered
from
recurrent herpes labialis.

4. An american reporter had heat
stroke while he was covering
news in Sub-Saharan Africa

5. Painful leg ulcer in a DM patient

6. Young epileptic on valproate
developed TEN

7. What is the
function of
SKIN?
Preservation and
reproduction of DNA
What are the requirements of skin for the
protection and duplication of DNA?

8.  Skin is the largest organ in the body
 In a 70-kg individual, the skin weighs over 5 kg
 Covers a surface area approaching 2 m2

9. Beauty may be skin–deep but skin has 4 layers

10. Epidermis is not dead
Protein rich
corneocytes
Cells of epidermis:
1. Keratinocytes
2. Langerhan’s cells
3. Mast cells
4. Melanaocytes
5. Markel cells
Lipid rich
lamellar bodies

11. Membrane proteins:
- Plakins
Granulocyte precursor:
- Loricrin
- Profilaggrin
Cytosolic precursors:
-Involucrin
- Small prolin rich protein
Calcium
Envelope proteins
Lamellar
body:
Ceramide
Fatty acid
Cholestreol
Cholesterol
esters
Corneocyte
Glutamyl lysyl isodipeptidase bond
Transglutaminase (TG 1-5)
Protein-rich corneocytes are embedded
within a continuous lipid-rich matrix

12. Dermo-epidermal junction

13. Vascularized dermis provides
structural and nutritional support
-Vessels
- ECM
- Receptors and nerves
- Erector pili muscle
- Pilosebaceous unit
- Hair

14. Extracellular matrix
Elastin
-Elasticity
-Resilience
Collagen
-tensile strength,
-protects against trauma
Proteoglycan/glycosaminoglycan
- hydration
Non-collagenous glycoproteins
- facilitate cell-matrix interactions

15. Pilosebaceous
Unit
1.Terminal on the scalp and beard
2.Vellus on the majority of skin
3. Sebaceous on the chest, back and face
4. Apopilosebaceous in axilla and groin
Glands of skin
Eccrine galnd: Sweating
• Insensible and active
• Thermal and mental
• Sole, forehead and palm
Apocrine glands: Pheromones
•
•
•
•
•
•
Axilla
Nipples
Pubic/genital/circum-anal area
Lips and circumoral
Eyelids
Outer ear

16. ‘Barrier’ function of skin
TEWL
Noxous
agent
 Intact stratum
corneum
 Lipid-rich
(Polar molecules
envelope
Can get thru lipid layer)
 Keratin
 Keratin
 Sebum
 Immunity
Stretching
 ECM
Trauma

Subcutaneous
fat
(80% of fat is in
the subcutis)
Light/
UV Ray
 Thickened
epidermis
Stratum
corneum
 Melanin
(-brown/black
=eumelanin
-yellow/red
=phaeomelanin)

17. Skin: An immunological unit
Innate immunity
1.
2.
3.
4.
Complements
Toll Like Receptors (TLR)
Antimicrobial peptides (AMP)
Macrophages
Adaptive immunity
1. Antigen presenting cells (LC, DC)
2. Lymphocytes
3. Cytokines & Immunoglobulins

18. TLRs have emerged as a major class of
pattern recognition receptors in skin

19. AMPs
•
•
•
•
•
Cathelicidins
β-defensins
Adrenomedullin
Cystatin
Secretory protease inhibitor
• Alarmins
- Broad spectrum of antimicrobial activity
- Chemotactic for inflammatory cells
- Promoting histamine release from mast cells
- Adjuvant in enhancing antibody production
- Increases the expression of TNF-α and IL-1
- Barrier repair and wound healing

20. Langerhan’s cells –
Survey the epidermal environment
Antigen presentation to T-cells
Dendrite surveillance
extension and retraction
cycling habitude
(dSEARCH) allows an
efficient antigen sampling
 Short-term LCs developed from Gr1hi monocytes under inflammatory conditions
 Long-term LCs arose from bone marrow in
steady state and depend on Id2
 LC reconstitution occurs in two waves:
- Initial fast and transient wave of short-term LCs
- Second wave of long-term LCs.

21. Immune Response
Effector cells
1.
2.
3.
4.
5.
6.
7.
Th1, Th2 cells (CD4)
Tc CELLS (CD8)
Treg cells
NK cells (UV-induced immunosuppression )
γ/δT cells (Leprosy, leishmnaiasis)
DETCs (protect keratinocytes)
B cells and Ig

22. Circulation
2-way haematogenous system
1. Nutritional support
2. Delivery of leucocytes
3. Thermoregulation
1-way lymphatic system
- Adaptive immunity
 Extensive subcutaneous venous plexus
hold large quantities of blood
dissipate heat from the surface of the skin
 Arteriovenous anastomoses
prominent in areas exposed to maximal cooling
volar surfaces of the hands, feet, lips, nose, ears

23. Interfacing with External and Internal Environments:
Skin is a Communicating Organ
‘Wired’ communication
Autonomic system (cholinergic)
1.
Vasomotor functions
2. Pilomotor activity
3.
Eccrine sweat gland secretion
Sensory system
 Mechanoreceptors for touch
• Skin:
Rapidly adapting - Meissner’s corpuscle
- Slowly adapting - Merkel’s receptor
• Subcutaneous tissue :
Rapidly adapting - Pacinian corpuscle,
Slowly adapting - Ruffini’s corpuscle,
 Thermoreceptor
Cold receptors
Warmth receptors
 Nociceptors
‘Wire-less’ communication
Cellular communication
- APC
- Lymphocytes
- Mast cells
Communication via hormones
- ACTH in skin pigmentation
- Vit D3 from epidermis
- Pheromones from apocrine glands
- MSH in appetite
- Leptin from subcutaneous adipocytes
Communication via cytokines
- Keratinocytes produce IL-1, IL-8, TGF-β
- Mast cells produce TNF
- Vascular endothelial cells produce IL-1β, IL-6

24. Skin: conveyer of beauty & physical attraction;
server of socio-sexual communication
The skin, by virtue of its visual appeal, smell and feel, has an important role in
social and sexual communication in humans
On Beauty: Evolution, Psychological consideration and surgical enhancement: Allan & Dover

25. Pheromones – myth or reality?
•
Musky odour composed of 3-olcompound degraded by bacteria
•
Kalogeraki & Beiber - Boys show
aversion to the odor of fathers but
feels attraction to the odor of
mothers (Oedipaus complex)
•
Russel – Babies suck on only to
mother’s
breast.
Mother
unconsciously marks her baby with
a distinctive smell (Russel effect)

26. Skin is so busy that sometimes it fails!
Skin failure
‘A loss of normal temperature control with inability to maintain the core
temperature, failure to prevent percutaneous loss of fluid, electrolytes and protein
with resulting imbalance and failure of the mechanical barrier to penetration of
foreign materials’
Examples
• Thermal Burns
• Stevens–johnson Syndrome,
• Toxic Epidermal Necrolysis,
• Graft-versus-host Disease

27. Bioengineering and the skin
•
•
•
•
•
•
•
TEWL measurement is used to assess the barrier function of skin
Transcutaneous oxygen tension (tcPo2) measurement to assess skin perfusion
Botox injection: decrease facial lines and sweating in disabling hyperhydrosis
Skin grafting
Finger-printing
Stem cells can be collected from skin
LC and DC capture protein antigens: Possible targets for vaccination

28. What we have learned today?
Immunological
function
Sensory
unit
Absorption
Sociosexual
communication
Endocrine unit
Waterproofing
Excretion of
waste
1. Structural organization
2. Skin: Multitasking unit
3. Skin immunity
4. Skin failure
5. Skin bio-engineering
Mechanical
barrier
Pigmentory
unit
Temperature
regulation
Elastic
function

29. DNA
damage by
UV ray
Compromised
chemical and
immune
barrier
Loss of
thermoregulation
Vascular
damage
Problems revisited
Skin
failure
with
massive
TEWL

30. Thank you
What spirit is so empty and blind, that it
cannot recognize the fact that the foot is more
noble than the shoe, and skin more beautiful
than the garment with which it is clothed Michalangelo