Anatomy & Physiology of the integumentary system

1. THE INTEGUMENTARY SYSTEM

2. THE INTEGUMENTARY SYSTEM
 the largest body
system
skin and the skin
derivatives - hair,
nails and skin
(exocrine) glands.
 The integument
(skin) as an organ

3. THE INTEGUMENTARY SYSTEM
The integument (skin)
 the largest organ of the body
 16% of body weight
 1.5 to 2 m2
in area
 made up of 2 parts:
1. Cutaneous membrane
a. Epidermis - epithelium/epithelial tissue
b. Dermis - connective tissue (CT) with blood
supply
2. Accessory structures
a. Hair
b. Nails
c. Exocrine glands

4. Functions of the Integumentary System
Protection
 First line of defense against
(bacteria & viruses)
 Protects underlying structures from
UV radiation & dehydration
Vitamin D production
 Needed for calcium absorption
Sensation
 Sensory receptors

5. Body temperature regulation
 If too hot
 Dermal blood vessels dilate
 Vessels carry more blood to surface
so heat can escape
 If too cold
 Dermal blood vessels constrict
 Prevents heat from escaping
Excretion
 Small amounts of waste products
are lost through perspiration
Functions of the Integumentary System

6. STRUCTURE OF SKIN
The Epidermis
 Epithelial tissue
 Dermis
 Dense irregular
connective tissue
Hypodermis
(Subcutaneous tissue)
 loose connective
tissue and adipose
(fat) tissue

7. Skin Structure: EPIDERMIS
The Epidermis
 avascular (without
blood vessels)
 stratified squamous
epithelium
 Nutrients and oxygen
diffuse in this layer from
capillaries in the dermis
 Keratinocytes - the most
abundant cells in the
epidermis.

8. Skin Structure: EPIDERMIS
 The 5 strata of keratinocytes in
thick skin
 From basal lamina to free
surface
1. Stratum basale
2. Stratum spinosum
3. Stratum granulosum
4. Stratum lucidum
5. Stratum corneum

9. Skin Structure: EPIDERMIS
Stratum basale
 has many basal cells or
germinative cells
 attached to basement membrane
(by hemidesmosomes)
 forms a strong bond between
epidermis and dermis
 dermal papillae (tiny mounds)
 epidermal ridges (fingerprints)

10. Skin Structure: EPIDERMIS
 Stratum spinosum
(the “spiny layer”)
 produced by division of stratum
basale
 8-10 layers of keratinocytes (bound
by desmosomes)
 cells shrink until cytoskeletons stick
out (spiny)
 cells continue dividing, increasing
thickness of epithelium
 contain dendritic (Langerhans)
cells (active in immune response)

11. Skin Structure: EPIDERMIS
Stratum granulosum
(the “grainy layer”)
 Stops dividing, starts producing
 Keratin
 tough, fibrous protein
 makes up hair and nails
 Keratohyalin
 dense granules
 cross-link keratin fibers

12. Skin Structure: EPIDERMIS
Stratum lucidum - the “clear
layer”
 found only in thick skin
 covers stratum granulosum
Stratum corneum - the “horn layer”
 exposed surface of skin
 15-30 layers of keratinized cells
 water resistant
 shed and replaced every 2 weeks

13. Skin Structure: EPIDERMIS
Thin Skin
 Covers most of the body
 Has 4 layers of keratinocytes
 Thick Skin
 Covers the palms of the hands
and soles of the feet
 Has 5 layers of keratinocytes

14. Skin Structure: DERMIS
The Dermis
 located between epidermis and
subcutanoues layer
 anchors epidermal accessory structure
(hair follicles, sweat glands)
 two components
1. outer papillary layer
2. deep reticular layer

15. Skin Structure: DERMIS
The Papillary Layer
 located between epidermis and
subcutanoues layer
 anchors epidermal accessory
structure (hair follicles, sweat glands)
 The Reticular Layer
 consists of dense irregular CT
 contains larger blood vessels,
lymphatic vessels, and nerve fibers
 contains collagen (strong) and elastic
(elastic & flexible) fibers
 contains connective tissue proper

16. DERMATITIS
An inflammation of the papillary
layer.
Caused by:
 infection, radiation, mechanical irritation
or chemicals (e.g. poison ivy)
Characterized by itch or pain

17. Burns (Skin)
• Tissue damage caused by heat, electricity, radiation,
chemicals
• Main threat: loss of fluids (dehydration, electrolyte
imbalance)
• Kidney failure, circulatory shock
• Treatment: replace fluids via IV
• Rule of Nines: estimating extent of burns
• Divide body into 11 areas
• Each part is 9% of total body area +1% genital region

18. Rule of Nines

19. Classifying of Burns
• 1st- degree burns: only epidermis damaged → swelling,
redness, pain (sunburn)
• 2nd- degree burns: injure epidermis & upper dermis →
redness and pain; blisters
• 3rd- degree burns: entire thickness of skin, destroy nerve
endings (no pain) → need skin graft

21. First-degree Burn

22. Second-degree Burn

23. Third-degree Burn

24. Critical Burn
• >25% of body with 2nd degree burns
• >10% of body with 3rd degree burns
• 3rd degree burns on face, hands, feet
• Face: swelling of respiratory passages → suffocation
• Joints: scar tissue formation limits mobility

25. Skin Graft

26. Skin Structure: HYPODERMIS
 The HYPODERMIS
(Subcutaneous layer)
 lies below the integument
 stabilizes the skin
 allows separate movement
 made of elastic areolar and adipose
tissues
 connected to the reticular layer of
integument by connective tissue fibers.
 Deposits of Subcutaneous Fat
 distribution patterns determined by
hormones
 reduced by cosmetic liposuction
(lipoplasty)

27. Skin Structure
The Hair Follicle
 hair follicles are the organs that
form the hairs
 located deep in dermis
 produces nonliving hairs
 wrapped in a dense CT sheath
 base is surrounded by sensory
nerves (root hair plexus) -
control bacteria

28. Structure of Hair
Regions of the Hair
 Hair root
lower part of the hair
attached to the integument
 Hair shaft
 upper part of the hair
 not attached to the integument

29. Hair Function
Head
 UV protection
 cushion from trauma
 insulation
 Nostrils, Ear canals and Eyelashes
 prevent entry of foreign material
 Root hair plexus
 sensory nerves at base of hair follicle that detect slight
movement of hair
 Arrector pili muscle
 attached to every hair follicle
 contract to stand hair perpendicular to skin surface

30. Structure of Hair
Accessory structures of
Hair
 Arrector pili
involuntary smooth muscle
causes hairs to stand up
produces “goose bumps”
 Sebaceous glands
 lubricate the hair

31. Structure and Function of Nail
Nails
 protect fingers and toes
 made of dead cells packed
with keratin
 metabolic disorders can
change nail structure
 Nail Production
 occurs in a deep epidermal
fold near the bone called the
nail root

32. - End -