2. Learning Outcomes
After completing this system, students should be able to:
•Define intergumentary system
•Give its organs
•Identify the functions of skin and its appendages
•List the layers of epidermis and cells that compose them
• State the composition of papillary & reticular layers of
dermis iv.
• Discuss the structure & functions of skin appendages
(hair, glands and nail)
•Know diseases affecting the system
3. INTEGUMENTARY SYSTEM
• Defn I.S- set of organs that forms the external covering of the
body and protects it from many threats such as infection,
desiccation, abrasion, chemical assault and radiation damage
• 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.
4. INTEGUMENTARY SYSTEM
• Integumentary 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:
– Cutaneous membrane
• Epidermis– Superficial epithelium
• Dermis – underlying CT with blood supply
– Accessory structures
• Hair
• Nails
• Exocrine Glands
• SKIN - cutaneous membranecovers external surface of body largest organ
• The epidermis, the underlying structure is the DERMIS: Made of connective
tissues and then Hypodermis- with adipose and areolar tissues
5. Functions of integumentary system
• 1 Protection
• First line of defense against Bacteria ,Viruses
• Protects underlying structures from
• Ultraviolet (UV) radiation
• Dehydration
• 2 Vitamin D production
• Needed for calcium absorption
• 3 Sensation
• Sensory receptors
• 4 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
• 5 Excretion
• Small amounts of waste products are lost through perspiration
6. SKIN FUNCTIONS
protection- against invasion of microorganisms, water loss and
dehydration.
defense- contains macrophages, lymph nodes and other structures
which identify pathogens and provide first line of defense against
them.
sensation - the skin contains sense organs for light touch, pressure,
temperature, and pain.
secretion - the skin secretes the precursor to Vitamin D (this is then
activated by processing in the liver and kidney), and melanin.
thermoregulation - by diverting blood into or away from the skin the
body can release or conserve heat.(body temp regulation)
excretion – small amount of waste are lost through the skin
10. • Langerhan’s cells
• Originate from bone marrow
• Participate in immune response
• Site of invasion of HIV
• Merkel Cells
• Least numerous
• Deepest layer
• Associated with Merkel (tactile) disc
11. • Keratinocytes
• • arranged in 4-5 layers • 90 % of epidermal cells
• • Produce:
• Protein keratin (tough, fibrous)
– protection
• Lamellar granules
– water-repellant sealant
• Melanocytes
• Produce melanin (brown-black pigment); contributes to skin color
• Everyone have same number
• shield DNA from being damaged by UV
13. • Stratum basale
• deepest layer
• single row of cuboidal/ columnar of actively dividing keratinocytes
• melanocytes, Langerhan’s cells & Merkel cells
• Stratum spinosum
• 8- 10 layers of keratinocytes
• projections of melanocytes & langerhan’s cells
• Stratum granulosum
• 3-5 layers of flattened keratinocytes that undergo apoptosis
• degeneration of nuclei and organelles
• ** apoptosis- genetically programmed cell death
14. • Stratum lucidum
• present only in skin of fingertips, palms & soles
• 3-5 rows of clear, flat, dead keratinocytes
• Stratum corneum
• 25-30 rows of dead, flat keratinocytes
• continously shed & replaced by cells of deeper layer
• protection against abrasion and penetration
19. SKIN COLOR
• 3 pigments
• Melanin ( pale-yellow-tan-black )
• Carotene (yellow-orange)
– Precursor of Vit. A
– Subcutaneous & fatty area
• Hemoglobin (red)
– O2-carrying pigment
• Melanin
• different skin color due to amount of pigment produce
• freckles: accumulation of melanin
• > UV exposure, > melanin production,
• > protective against UV radiation
20. APPENDAGES OF SKIN
• Hair
• Nail
• Glands
– Sweat glands
– Sebaceous glands
• Hair
• Functions:
• warmth
• protection (scalp injury, sun)
• shield from foreign particles (e.g. eyelashes)
• filters (nostrils)
• Structure of the hair
• Shaft – project from surface
• Root- embedded in dermis
• Bulb- base of root; enclosed in hair follicle; associated with arrector pili muscle
23. NAILS
• plates of tightly, packed, hard, keratinized
epidermal cells
• clear, solid covering over dorsal of fingers
• Protection from trauma
• “
Tools”- to grasp and manipulate
28. Glands cont…
• Sebaceous (oil) glands
• groups of specialized epithelial cells
• secrete oil or sebum
• everywhere,+ +except palms & soles
• usually secrete into hair follicles
• lubricates hair and skin
– softens dead cells (pliability )
– slows water loss
– bactericidal
• stimulated by hormones (androgens)
29. Wound healing
• events that repairs the skin to its normal (or near-
normal) structure & function
• 2 kinds (depending on depth of injury ): -
EPIDERMAL wound healing
– affects only epidermis
– DEEP wound healing
– penetrates dermis
31. • Scar formation- fibrosis
• Hypertrophic scar
– scar elevated above normal epidermal
• surface; but within boundaries of original wound
• Keloid scar
– extend beyond boundaries into the normal surrounding tissue
• Differences between scar and normal skin tissue
• Collagen fibers more densely arranged in scar tissue
• Less blood vessel, unequal number of hairs, skin gland & sensory
structure
• More lighter in color (due to arrangement of collagen & scarcity of
blood vessel)
