SKIN ANATOMY and FUNCTION

Budipratiwi W.

Fac of Pharmacy Jember University

SKIN• Cover body surface (> 20.000 cm2)

• The largest organ of the body, functions:

– receives and transports,

– reacts to external stimuli,

– protects the body from external factors,

– It is container, defender, regulator, breather, feeler, and adaptor

• Requires attention and maintenance to function properly

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EPIDERMISFive layers:1. Stratum corneum

2. Stratum lucidum

3. Stratum granulosum

4. Stratum spinosum

5. Stratum germinativum

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• STRATUM CORNEUM (Horny Layer)

Control drug absorption and others

20-30 cell layers thick, almost ¾ of epidermal thickness

Flat & dead cells

• STRATUM LUCIDUM

Most thin layer of epidermal

Clear, flat, and dead cells

• STRATUM GRANULOSUM

Area of 3-5 cell layers

Flattened cells, contain dark granules (flatten keratinocytes)

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• STRATUM SPINOSUM

– Made of Keratinocytes

– Contain a web-like system of filaments

• STRATUM GERMINATIVUM

– Single row of youngest layer

– Basal cells which devide & differentiate into other cells in the epidermis

– Contain melanocytes (gives skin its colour)

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Stratum Corneum• Corneocyteprotein

complex, made of keratin• Cornified envelope (loricrin

and involucrin)• Attached to the envelope ceramide lipids

• Corneodesmosomes• Natural moisturizing factor

(NMF)• Free fatty acids and

ceramides (released from the lamellar bodies) lamellar lipid bilayer (maintain the barrier properties of the skin)

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Stratum Lucidum

• The stratum lucidum is normally only well seen in thick epidermis and represents a transition from the stratum granulosum to the stratum corneum.

• Epidermis varies in thickness: – on frictional forces – thickest on the palms

of the hands and soles of the feet

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Stratum Granulosum

• The cells of the stratum granulosum (SGR) accumlate dense basophilic keratohyalingranules (seen on the close-up view).

• These granules contain lipids, which along with the desmosomalconnections form a waterproof barrier prevent fluid loss from the body

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• accumulate many desmosomes on their outer surface which provide the characteristic “prickles”(seen on the close-up view) of the stratum spinosum (SS), which is often called the prickle-cell layer.

Stratum spinosum

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stratum germinativumprovides the germinal cells necessary for the regeneration of the layers of the epidermis After a mitotic division, a newly formed cell (keratinocytes) will undergo a progressive maturation called keratinization as its migrates to the surface

Stratum germinativum

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DERMIS• About 3-5 mm thicks

• Richly supplied with blood vessels and sensory nerve endings

• Contains mostly fibroblasts (responsible for secreting: collagen, elastin and immune cells)

• Divide into: papilary and reticular layer

• It’s home to most of the skin’s structure (skin appendages), including Sweat & Oil Glands, Hair Follicles, Nerve Endings, Blood and lymph vessels

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Sweat & Oil Glands• Eccrine glands

– True sweat glands, regulate body temperature

– Respond to heat, exercise, and fever

– Some respond to emotional strees

• Apocine glands

– Only in the armpit & pubic region

– Secrete a milky sweat, encourages bacterial growth – body odor

• Sebaceous glands

– Found everywhere, except for the palms & soles

– Helps skin smooth & protects against bacteria and fungi overgrowth