A AND P INTEGUMETARY SYSTEM

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The integument as an organ:
 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
 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
THE INTEGUMENTARY SYSTEM

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a. Hair
b. Nails
c. Exocrine Glands
INTRODUCTION
 The skin is an extensive organ which forms the outer covering of the body.
 It is continuous with mucous membrane lining the body orifices.
 The skin has 2 layers.
1. A superficial layer- the epidermis- made up of stratified squamous
epithelium
2. A deeper layer-the dermis made up of connective tissue.
3. Hypodermis - subcutaneous tissue- loose connective tissue proper and
adipose tissue
 The junction between these two layers is markedly wavy because of tee
presence of finger like extensions from the dermis-the dermal papillae.
SKIN STRUCTURE: EPIDERMIS

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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
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

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 Has five layers of keratinocytes
STRUCTURES OF THE EPIDERMIS
 The five strata of keratinocytes in thick skin
 From basal lamina to free surface
 Stratum basale
 Stratum spinosum
 Stratum granulosum
 Stratum lucidum
 Stratum corneum
 Stratum Basale
 Is attached to basement membrane by hemidesmosomes
 Forms a strong bond between epidermis and dermis
 Forms epidermal ridges (e.g., fingerprints)

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 Dermal papillae (tiny mounds)
 Increase the area of basement membrane
 Strengthen attachment between epidermis and dermis
 Has many basal cells or germinative cells
 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
 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
 Stratum Lucidum — the “clear layer”
 Found only in thick skin
 Covers stratum granulosum
 Stratum Corneum — the “horn layer”

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 Exposed surface of skin
 15 to 30 layers of keratinized cells
 Water resistant
 Shed and replaced every 2 weeks
THE DERMIS
 Located between epidermis and subcutaneous layer
 Anchors epidermal accessory structures (hair follicles, sweat glands)
 Two components
 Outer papillary layer
 Deep reticular layer
The Papillary Layer
 Consists of areolar tissue

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 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
DERMATITIS
 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

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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)

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FUNCTIONS OF THE INTEGUMENTARY SYSTEM
 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

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 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
APPENDAGES OF THE SKIN
THEY ARE:
1. HAIRS
2. NAIL
3. SWEAT GLANDS
4. SEBACEOUS GLAND
STRUCTURE OF HAIR
 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.

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 Base is surrounded by sensory nerves (root hair plexus).
 Control bacteria
 Accessory Structures of Hair
 Arrector pili
 Involuntary smooth muscle
 Causes hairs to stand up
 Produces “goose bumps”
 Sebaceous glands
 Lubricate the hair
Regions of the Hair
 Hair root
Lower part of the hair

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Attached to the integument
 Hair shaft
Upper part of the hair
Not attached to the integument
 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

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HAIR FUNCTION
 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
STRUCTURE & 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

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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

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SEBACEOUS GLAND
They are seen in relation to the hair follicles.
Each gland consists of a number of alveoli that are connected to a duct.

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This duct opens in to the hair folicle.
As mentioned earlier, the sebaceous gland is situated between the hair folicle and
the arrector pilli muscle.
When the muscle contracts,it sequeezess the gland,which facilitates the discharge
of its secretions in to hair folicle.
Functions of sebum
1. Its oily nature helps to keep the skin and hair soft
2. It prevents drying of skin
3. It makes the skin resistant to moisture.
Modified sebaceous glands
The tarsal glands or eyelids are modified sebaceous glands. They are called
maibomian glands
SWEAT GLANDS
Sweat glands produce sweat or perspiration.
There are 2 type of sweat glands in the body:
1. Typical
2. Atypical
Typical sweat gland
A typical sweat gland consists of a single long tube.
The lower end of the tube is highly coiled forming the body of the gland.it
usually lies in the reticular layer of the dermis.
Atypical sweat gland
Atypical sweat glands are found in the following regions:
THE SECRETION OF SEBACEOUS
GLAND IS CALLED “ SEBUM”

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1. Axilla
2. Nipple and areola
3. Perianal region
4. The glans penis
5. Some parts of female external genitallia.
These glands are larger in size. They show branching. Their ducts open in
to hair folicles.their secretions are viscous.
The secretions of atypical glands are odorless but due to bacterial
decomposition they give off body odors.
Modified sweat gland
1. Ceruminous glands of external auditory meatus
2. Ciliary glands of eyelids
3. Mammary gland.
BLOOD SUPPLY OF SKIN
 Skin is highly vascular organ.
 It derives its arterial blood from a number of plexuses.one plexus of arteries is
present over the deep fascia, another plexus, just below the dermis, is called
reticular plexus, the papillary plexus lies just below the dermal papilla.
Capillary loops arising from this plexus pass in to each dermal papilla.
 The epidermis has no blood supply.
 It derives its nutrition entirely by diffusion from the capillary loops of the
dermal papillae.
 There are numerous arteriovenous anastomoses in the skin, which have an
important role in temperature regulation.
CUTANEOUS RECEPTORS OR EXTEROCEPTIVE RECEPTORS
These receptors present in the skin are concerned with touch , pain, temperature
and pressure.

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1. Free nerve endings
2. Tactile corpusles of meissner
3. Lamellated corpuscles of pacini
4. Tactile menisci or merkel cell endings