The Integumentary
System
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Integumentary system functions:
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Protection
Excretion
Temperature maintenance
Insulation and cushion
Vitamin D3 synthesis
Sensory detection
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The integumentary system consists of
 Cutaneous membrane
Epidermis
Dermis
 Accessory structures
 Subcutaneous layer
It is not part of the integumentary system
It separates the integumentary system from
the deep fascia
Also known as hypodermis and superficial
fascia
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Integumentary System
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The Epidermis
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Cells of the epidermis
Keratinocytes
Most abundant
Produce keratin
Fibrous protein that makes the epidermis
though and water resistant
Melanocytes
Secretes melanin
Protects the cell against UV rays
freckles
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Cells of the epidermis
Langerhan’s cells
Cells that belong to the immune system
Merkel cells
Merkel discs = Merkel cell + nerve ending
Sense of touch
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Layers of the epidermis:
 Stratum germinativum or basale
 Stratum spinosum
 Stratum granulosum
 Stratum lucidum
 Stratum corneum
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Layers of the Epidermis
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Stratum Germinativum (basale)
Single row of cells
Forms epidermal ridges
Basal or germinative cells
Merkel cells (touch)
Melanocytes
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Stratum Basale
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Stratum Spinosum
Prickle cells
Several layers of cells
Cells held together by desmosomes
Presence of Langerhan’s cells
Cells contain pre-keratin
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Stratum Granulosum
 3 to 5 layers of keratinocytes
 No cell divisions
 Lamellated granules
Contain a water resistant glycolipid that
reaches the extracellular space
 Keratohyalin granules
Combine with the intermediate filaments to
form keratin that will make the skin stronger
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Stratum lucidum (clear layer)
Dead keratinocytes
Flat cells
In thick skin
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Stratum corneum
Outmost layer
20-30 layers of cells
Dead cells
Cytoplasm filled with keratin
Constantly shedding and replaced
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The Dermis
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Dermal layers
Papillary layer
Contains blood vessels, lymphatics
Free nerve endings
Meissner corpuscles (touch, pressure)
Loose areolar connective tissue
Presence of dermal papillae
Produce fingerprints
• Genetically determined
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Dermal papilla
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Fingerprints
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Dermal layers
 Reticular Layer
Dense irregular connective tissue
Fewer cells
Contains network of collagen and elastic fibers
to resist tension
Sweat and sebaceous glands
Rich blood supply
Hair follicles
Pacinian corpuscles (deep pressure)
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Dermis
 Both layers are rich in collagen and elastic fibers
 Numerous fibroblasts, adipocytes, macrophages
 Richly vascularized
Regulation of body temperature
Decubitus ulcers
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Skin color depends on
 Blood supply
 Carotene
Present in the s.corneum and hipodermis
 Melanin
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Abnormal skin color
 Flushed
Fever, hypertension
 Pale
 Jaundice
 Cyanoses
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Accessory Structures
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Nails
 Nail body covers the nail bed
 Nail production occurs at the nail matrix
 Eponychium (cuticle) overlies root
 Free edge of nail extends over hyponychium
 Lunula
 Root
 Nail folds
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Nail
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Hairs
 Originate in hair follicle
 Composed of root and shaft
 Root base (hair papilla) surrounded by hair bulb
and root hair plexus
 Cuticle = superficial dead protective layer
 Cortex
 Medulla
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Hair
 Follicle
Epidermal layer
Internal epithelial root sheath
External epithelial root sheath
Glassy membrane
Connective root sheath
Papilla
Blood vessels enter the hair
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Hair
 Arrector pili muscle
Smooth muscle
When contracted cause dimpling of the skin
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Cutaneous Glands
 Sebaceous
 Sudoriferous
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Sebaceous glands
 Discharge waxy sebum onto hair follicle or on the
skin surface
 Not present on palms and soles
 Sebum
Oil + dead cells
Keep skin and hair moist
Black head
Acne
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Sebaceous Glands and Follicles
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Sudoriferous glands
 Apocrine sweat glands
Axilla and genital areas
Begin secretion at puberty
Produce odorous secretion rich in protein and
fat
 Merocrine (eccrine) sweat gland
All over the body
Regulates body temperature
Sweat or perspiration
Water, salt, urea
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Sweat Glands
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