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Integumentary SystemS.S.MOORTHY SEMENCHALAM

M.Sc. Comm Health (Occ Health) UKMB.HSc. Nursing (Aust)

Dip Med Sc. (Moh)

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Learning Outcomes

After completing this system, students should be able to:

i. Identify the functions of skin

ii. List the layers of epidermis and cells that compose them

iii. State the composition of papillary & reticular layers of dermis

iv. Discuss the structure & functions of skin appendages (hair, glands and nail)

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INTEGUMENTARY SYSTEM

• consists of skin & its accessory structures (inc. glands, hair & nails)

• SKIN - cutaneous membrane- covers external surface of body- largest organ

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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.

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Cont.

• 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.

• excretion – small amount of waste are lost through the skin

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STRUCTURE OF THE SKIN

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The layers/ strata of the skin….

EPIDERMIS

superficial

thinner portion of epithelial tissue

DERMIS

connective tissue

deeper, thicker

SUBCUTANEOUS LAYER

adipose & areolar tissue

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SUBCUTANEOUS TISSUE

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EPIDERMIS- contains 4 principal types of cell

Keratinocytes Melanocytes Langerhan’s cells Merkel cells

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Keratinocytes• arranged in 4-5 layers• 90% of epidermal cells• Produce:(i) Protein keratin (tough, fibrous)

- protection (ii) Lamellar granules

- water-repellant sealant

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Melanocytes

• Produce melanin (brown-black pigment); contributes to skin color

• Everyone have same number• shield DNA from being damaged by UV

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Langerhan’s cells

• Originate from bone marrow• Participate in immune response• Site of invasion of HIV

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Merkel Cells

• Least numerous• Deepest layer• Associated with Merkel (tactile) disc

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EPIDERMIS: STRATA stratum basale (germinativum)

stratum spinosum (prickly layer)

stratum granulosum (granular)

stratum lucidum (clear layer)

stratum corneum (horny layer)

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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

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Stratum granulosum

• 3-5 layers of flattened keratinocytes that undergo apoptosis

• degeneration of nuclei and organelles

** apoptosis- genetically programmed cell death

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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

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DERMIS• connective tissue; collagen & elastics fibers• 2 layers

Papillary layer- superficial portion (1/5)- loose fibers- contains dermal palpillae that house capillaries, corpuscles of touch & free nerve endings

Reticular layer - deeper portion (4/5) - dense connective tissue - spaces between fibers; adipose cells, hair follicles, nerves, sebaceous

glands

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SUBCUTANEOUS LAYER• Subcutaneous tissue• Deep to dermis• Storage depot for fat• Anchors skin to underlying tissue• Blood vessels & nerves ending: Pacinian

corpuscle (sensitive to pressure)

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SKIN COLOR• 3 pigments(i) Melanin (pale-yellow-tan-black)(ii) Carotene (yellow-orange)

- Precursor of Vit. A- Subcutaneous & fatty area

(iii) Hemoglobin (red)- O2-carrying pigment

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Melanin

• different skin color due to amount of pigment produce

• freckles: accumulation of melanin• > UV exposure, > melanin production,

> protective against UV radiation

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APPENDAGES OF SKIN

Hair

Nail

Glands Sweat glands

Sebaceous glands

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Hair

Functions:• warmth• protection (scalp injury, sun)• shield from foreign particles (e.g. eyelashes)• filters (nostrils)

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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

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Structure of the hair

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Nails

plates of tightly, packed, hard, keratinized epidermal cells

clear, solid covering over dorsal of fingers

Protection from trauma

“Tools”- to grasp and manipulate

Free edge (extend past distal end)

Nail body (visible portion)

Lunula

Eponychium (cuticle)

Nail-root (portion; buried in skin fold)

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Sweat (Sudoriferous) glands

• everywhere; except nipples & external genitilia

• types:a. Eccrine sweat glandsb. Apocrine sweat glandsc. Ceruminous glandsd. Mammary glands

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Eccrine sweat glands• abundant, with odorless secretion• most numerous (palms, soles, forehead),

originate in subcutaneous layer• produce sweat (99% water)• excrete salts, vitamin C, antibodies, metabolic

wastes, lactic acid• thermoregulation (lower body temperature)• autonomic nervous system

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Apocrine sweat glands

less numerous, secretions that develop odors axillary, groin ducts empty into hair follicles true sweat and fatty acids viscous, milky, bacteria food active during puberty sympathetic nervous system (pain, stress)

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Ceruminous glands• modified apocrine glands• secrete cerumen (ear wax)• external auditory canal

Mammary glands■ modified sweat glands

■ secrete milk

■ breast

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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)

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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

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Scar formation- fibrosis

• Hyperthropic scar- scar elevated above normal epidermal surface; but within boundaries of original wound

• Keloid scar- extend beyond boundaries into the normal surrounding tissue

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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)

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Thank you….

Questions please!!