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System
The BY
MR. JAYDIP NINAMALECTURER
SCON/SSON,ZUNDAL
Integumentary
THE INTEGUMENTARY SYSTEM
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:
THE INTEGUMENTARY SYSTEMThe 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 membranea. Epidermis– Superficial epithelium
b. Dermis – underlying CT with blood supply
2. Accessory structuresa. Hair
b. Nails
c. Exocrine Glands
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
Functions of the Integumentary System
Body temperature regulationIf too hot
Dermal blood vessels dilateVessels carry more blood to surface so heat can
escapeIf too cold
Dermal blood vessels constrictPrevents heat from escaping
ExcretionSmall amounts of waste products are lost
through perspiration
STRUCTURE OF SKIN 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
Skin Structure: EpidermisThe Epidermis
Is a vascular stratified squamous epitheliumNutrients and oxygen diffuse from capillaries in the
dermis
Cells of the EpidermisKeratinocytes
Contain large amounts of keratin
Are the most abundant cells in the epidermis
Skin Structure: Epidermis
The structural relationship andinterface between the epidermisand underlying dermis. Theproportions of the various layersdiffer with the location sampled.
Dermis
Epidermis
Epidermalridge
Dermalpapilla
Skin Structure: Epidermis
Thin SkinCovers most of the body
Has four layers of keratinocytes
Thick SkinCovers the palms of the hands and soles of
the feet
Has five layers of keratinocytes
Skin Structure: EpidermisStructures of the Epidermis
The five strata of keratinocytes in thick skin
From basal lamina to free surface1. Stratum basale2. Stratum spinosum3. Stratum granulosum4. Stratum lucidum5. Stratum corneum
Thick skin LM 210
Surface
Stratumcorneum
Stratumlucidum
Stratumgranulosum
StratumspinosumStratum basaleBasementmembraneDermisPapillary layer of dermis
EPIDERMIS
Skin Structure: EpidermisStratum Basale
Is attached to basement membrane by hemidesmosomes
Forms a strong bond between epidermis and dermisForms epidermal ridges (e.g., fingerprints) Dermal papillae (tiny mounds)
Increase the area of basement membraneStrengthen attachment between epidermis and dermis
Has many basal cells or germinative cells
Skin Structure: Epidermis
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
Skin Structure: EpidermisStratum 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
Skin Structure: Epidermis
Stratum Lucidum — the “clear layer”Found only in thick skinCovers stratum granulosum
Stratum Corneum — the “horn layer”Exposed surface of skin 15 to 30 layers of keratinized cellsWater resistantShed and replaced every 2 weeks
The Dermis Located between epidermis
and subcutaneous layer Anchors epidermal
accessory structures (hair follicles, sweat glands)
Two components1. Outer papillary layer 2. Deep reticular layer
Skin Structure: Dermis
Der
mis
Copyright reserved. 2012 The E Tutor
Skin Structure: Dermis The Papillary Layer
Consists of areolar tissueContains smaller capillaries, lymphatics, and sensory
neuronsHas dermal papillae projecting between epidermal ridges
The Reticular LayerConsists of dense irregular connective tissueContains larger blood vessels, lymphatic vessels, and
nerve fibersContains collagen and elastic fibersContains connective tissue proper
Dermatitis An inflammation of the papillary layerCaused by
infection, radiation, mechanical irritation, or chemicals (e.g., poison ivy)
Characterized by itch or pain
CharacteristicsStrong, due to collagen fibersElastic, due to elastic fibersFlexible
Hair
Papillarylayer
Reticularlayer
Cutaneousplexus
Papillaryplexus
Epidermalridges
Dermalpapillae
Capillary loopof papillary
plexusDERMIS
Skin Structure: HypodermisThe Hypodermis (Subcutaneous Layer)
Lies below the integumentStabilizes the skinAllows separate movement Made of elastic areolar and adipose tissuesConnected to the reticular layer of integument by
connective tissue fibers
Deposits of Subcutaneous FatDistribution patterns determined by hormonesReduced by cosmetic liposuction (lipoplasty)
Structure of HairThe 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
Exposedshaftof hair
Sebaceousgland
ArrectorpilimuscleConnectivetissue sheath
Root hairplexus
Structure of HairAccessory Structures of Hair
Arrector pili Involuntary smooth muscle Causes hairs to stand upProduces “goose bumps”
Sebaceous glands Lubricate the hair
Structure of Hair
Regions of the HairHair root
Lower part of the hairAttached to the
integument
Hair shaftUpper part of the hairNot attached to the
integument
Boundary betweenhair shaftandhair root
Hair shaft
SebaceousglandArrectorpili muscle
Hair root
Connectivetissue sheathHair bulbHair matrixHair papilla
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
Structure of Hair
Hair FunctionHead:
UV protectionCushion 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 hairArrector pili muscle:
Attached to every hair follicleContract to stand hair perpendicular to skin surface
Structure & function of NailNails
Protect fingers and toes
Made of dead cells packed with keratin
Metabolic disorders can change nail structure
Nail ProductionOccurs 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)
Structure & function of NailStructure of a Nail
Nail bodyThe visible portion of the nailCovers the nail bed
LunulaThe pale crescent at the base of the nail
Sides of nailsLie in lateral nail grooves Surrounded by lateral nail folds
Structure & function of Nail
A cross-sectional view
Lateral nail fold
Nailbody
Lateralnail
groove
Nailbed
Phalanx(bone of
fingertip)
Structure & function of Nail
A longitudinal section
Eponychium
Proximal nail foldNail root
Lunula Nail body
Epidermis Dermis Phalanx Hyponychium
The End
