The integumentary system is an organ system consisting of the skin, hair, nails, and exocrine glands. The skin is only a few millimeters thick yet is by far the largest organ in the body. The average person's skin weighs 10 pounds and has a surface area of almost 20 square feet.

1. Prepared by
Mr.Abhay Rajpoot
HOD (Dep. of Medical Surgical)
abhayrajpoot5591@gmail.com

2. The integument as an organ,
and is an alternative name
for skin.
The integumentary system
includes the skin and the skin
derivatives hair, nails, and
glands.
The integument as an organ:

3. The Integument
Is the largest system of the body
 16% of body weight,
 1.5 to 2m2
in area,
 The integument is made up of two parts:
1. Cutaneous membrane
a. Epidermis– Superficial epithelium
b. Dermis – underlying CT with blood supply
2. Accessory structures
a. Hair
b. Nails
c. Exocrine Glands

4. Protection
 First line of defense against
 Bacteria
 Viruses
 Protects underlying structures from
 Ultraviolet (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

6.  Understanding how the skin can function in these many
ways starts with understanding the structure of the 3
layers of skin
The Epidermis
Epithelial tissue
Dermis
Dense connective tissue proper – irregular
Hypodermis
Subcutaneous tissue- loose connective tissue proper
and adipose tissue

7. Epidermis
Dermis
Hypodermis
or
subcutaneous layer

8. The Epidermis
Is a vascular stratified squamous epithelium
Nutrients and oxygen diffuse from capillaries in the dermis
Cells of the Epidermis
Keratinocytes
Contain large amounts of keratin
Are the most abundant cells in the epidermis

9. Epidermis
Epidermal
ridge
Dermal
papilla
Dermis
The structural relationship and
interface between the epidermis
and underlying dermis. The
proportions of the various layers
differ with the location sampled.

10. Thin Skin
Covers most of the body
Has four layers of keratinocytes
Thick Skin
Covers the palms of the hands and soles of the feet
Has five layers of keratinocytes

11. Structures of the Epidermis
 The five 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

12. Thick skin LM  210
Surface
Stratum
corneum
Stratum
lucidum
Stratum
granulosum
Stratum
spinosum
Stratum basale
Basement
membrane
Dermis
Papillary layer of dermis
E
P
I
D
E
R
M
I
S

13. Stratum Basale
Is attached to basement membrane by
hemidesmosomes
Forms a strong bond between epidermis and dermis
Forms epidermal ridges (e.g., fingerprints)
Dermal papillae (tiny mounds)
Increase the area of basement membrane
Strengthen attachment between epidermis and dermis
Has many basal cells or germinative cells

14. Thick skin SEM  25
Pores of sweat
gland ducts
Epidermal
ridge
Epidermal ridges

15. Stratum Spinosum — the ―spiny layer‖
Produced by division of stratum basale
Eight to ten layers of keratinocytes bound by
desmosomes
Cells shrink until cytoskeletons stick out (spiny)
Continue to divide, increasing thickness of epithelium
Contain dendritic (Langerhans) cells, active in
immune response

16. Stratum Granulosum — the ―grainy layer‖
Stops dividing, starts producing
Keratin
A tough, fibrous protein
Makes up hair and nails
Keratohyalin
Dense granules
Cross-link keratin fibers

17. Stratum Lucidum — the ―clear layer‖
Found only in thick skin
Covers stratum granulosum
Stratum Corneum — the ―horn layer‖
Exposed surface of skin
15 to 30 layers of keratinized cells
Water resistant
Shed and replaced every 2 weeks

18. The Dermis
 Located between epidermis
and subcutaneous layer
 Anchors epidermal accessory
structures (hair
follicles, sweat glands)
 Two components
1. Outer papillary layer
2. Deep reticular layer Dermis

19.  The Papillary Layer
Consists of areolar tissue
Contains smaller capillaries, lymphatics, and sensory
neurons
Has dermal papillae projecting between epidermal ridges
 The Reticular Layer
Consists of dense irregular connective tissue
Contains larger blood vessels, lymphatic vessels, and nerve
fibers
Contains collagen and elastic fibers
Contains connective tissue proper

20. An inflammation of the papillary layer
Caused by
 infection, radiation, mechanical irritation, or chemicals
(e.g., poison ivy)
Characterized by
itch or pain
Characteristics
Strong, due to collagen fibers
Elastic, due to elastic fibers
Flexible

21. Hair
Papillary
layer
Reticular
layer
Cutaneous
plexus
Papillary
plexus
Epidermal
ridges
Dermal
papillae
Capillary loop
of papillary
plexus

22. 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)

24. Colour of the skin
Skin colour due to factors:
1. Presence of melanin: It is a dark pigment produced by
specialized cell called melanocytes
2. Accumulation of yellow pigment: This is the carotene colour
of the blood reflected through the epidermis. Melanocytes
are usually located in the deepest part of the stratum
Basale. Melanin is present all over skin. It is darker in
external genitalia, nipple area, anal region and arm pits.
Melanin is also resent in iris, retina of eye. Darker races
have slightly more melanin than light colour people.
The main function of melanin is to screen out excessive ultra
violet rays, protecting the nucleus and genetic material of cell

25. Skin Gland
1. Sweat Gland: There are two types of sweat glands.
These glands are distributed over nearly entire body surface. But
there are no sweat glands on nail beds, margin of lips, eardrum,
inner lips of vulva or tip o penis,
These glands are generally simple coiled tubular type. These glands
secrete sweat by a process called perspiration. When external
temperature increases, sweat from eccrine gland consists of
colorless fluid that contains:
 Neutral fat
 Albumin
 Urea
 Lactic acid se
 Sodium chloride (NaCI)
 Traces of sugar
 Ascorbic acid
Sweating regulates the body temperature.

26. Apocrine or odiferous glands: are situated more
deeply than’ eccrine gland. Apocrine gland becomes
active at puberty and enlarges just before puberty
2. Sebaceous (oil) glands: These are simple
branched, alveolar glands found in the dermis, These
glands are connected to hair follicle. The secretions
are produced by breaking down of the cells, which
form the oil secretion called sebum.
Sebum functions as a barrier, emollient and a
protective agent against bacteria and fungi. The main
function of these glands is lubrication and protection.

27. The Hair Follicle
 Hair follicles are the organs that form the hairs.
Hair follicles are the organs that form the hairs.
Located deep in dermis.
Produces nonliving hairs.
Wrapped in a dense connective tissue sheath.
Base is surrounded by sensory nerves (root hair plexus).
Control bacteria

28. Exposed
shaft
of hair
Sebaceous
gland
Arrector
pili
muscle
Connective
tissue sheath
Root hair
plexus
Accessory Structures of Hair
Arrector pili
Involuntary smooth muscle
Causes hairs to stand up
Produces ―goose bumps‖
Sebaceous glands
Lubricate the hair

29. 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
Boundary
between
hair shaft
and
hair root
Arrector
pili muscle
Hair shaft
Sebaceous
gland
Hair root
Connective
tissue sheath
Hair bulb
Hair matrix
Hair papilla

30.  Hair Shaft Structure
 Medulla
 Core, dead cells contain soft keratin and air to provide
flexible
 Cortex
 Middle layer, dead cells contain hard keratin to provide
stiffness
 Cuticle
 Outermost, overlapping dead keratinized cells form
shiny surface

31. Head:
UV protection
Cushion from trauma
Insulation
Nostrils, Ear canals, Eyelashes:
Prevent entry of foreign material
Body Hair:
sensory detection
 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

32. 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
Free edge
of Nail
Body of
Nail
Laternal
Nail fold
Lunula
Eponychium
(cuticle)

33. Structure of a Nail
Nail body
The visible portion of the nail
Covers the nail bed
Lunula
The pale crescent at the base of the nail
Sides of nails
Lie in lateral nail grooves
Surrounded by lateral nail folds

34. Function:
-Nails protect our fingers and toes
-These allow us to pick up and grasp the object
-These are use to scratch