Download - Anotomy of Skin
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INTEGUMENTARY SYSTEM
Prepared by,
Abhay S. Joshi
Assistant Professor
Yash Institute of Pharmacy, Aurangabad
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THE SKIN
• It is outer covering of body.
• In humans, it is the largest organ ofintegumentary system.
• It helps to maintain a constant bodytemperature, protects the body and providesensory information.
• Dermatology: It is the branch of medicalscience that deals with the diagnosis andtreatment of skin disorders.
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STRUCTURE OF SKIN
• The skin is the cutaneous membrane covers the external surface of the body/
• It is the largest organ of the body in both surface area and weight.
• The thickness of skin ranges from 0.5mm on the eyelids to 4.00 mm on the feet.
• The skin is composed of 2 layers
1. Epidermis
2. Dermis
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EPIDERMIS
• It is the outermost layer of skin.
• It is composed of keratinized stratified
squamous epithelium.
• It consists of principal types of cells
a) Keratinocytes
b) Melanocytes
c) Langerhans cells
d) Markel cell
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CELLS OF EPIDERMIS
Keratinocytes:
• About 90% of epidermal cells are keratinocytes
• Keratin is a tough, fibrous protein that helps toprotect the skin and underlying tissues from heat,microbes and chemicals.
Melanocytes:
• About 8% of the epidermal cells are melanocytes andproduce pigment melanin.
• Melanin is the yellow red or brown black pigmentthat contribute the skin color and absorb damagingUV light.
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CELLS OF EPIDERMIS
Langerhan’s cells:
• They arise from red bone marrow and migrate to the
epidermis & contribute a small fraction of the
epidermal cells.
• They participate in immune responses mounted
against microbes.
Markel cells:
• These are the least numerous epidermal cells.
• They are located in the deepest layer of epidermis.
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CELLS OF EPIDERMIS
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LAYERS OF EPIDERMIS
• Epidermis is composed of 5 layers:
1. Stratum corneum
2. Stratum lucidum
3. Stratum granulosum
4. Stratum basale (innermost layer)
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LAYERS OF EPIDERMIS
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LAYERS OF EPIDERMIS
1. Stratum corneum:
• It is the outermost layer of epidermis.
• Made up of 25-30 layers of flat, dead cells,
completely filled with keratin.
• Between the cells are lipids from smaller granules,
making it water repellant barrier.
• It is effective barrier against light, heat, bacteria,
water and many chemicals.
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LAYERS OF EPIDERMIS
2. Stratum Lucidum:
• It lies below the stratum corneum.
• It consist of 3-5 layers of clear, flat, dead cells lacking
granules and nuclei.
• The cells of stratum lucidum are also filled with
keratin.
• It is present only in skin of fingerprints, palms, and
soles.
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LAYERS OF EPIDERMIS
3. Stratum granulosum:
• In the middle of the epidermis is the stratum
granulosum.
• It consist of 3-5 layers of flattened keratinocytes.
• Cell contain the protein keratohyaline , which
converts tonofilaments into keratin and smaller
granules, which release a lipid rich, warer repellant
secretions.
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LAYERS OF EPIDERMIS
4. Stratum Spinosum:
• Superfacial to stratum basale.
• It consist of 8-10 layers of keratinocytes fits closely
together.
• It include projrctions of melanocytes and langerhans
cells.
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LAYERS OF EPIDERMIS
5. Stratum Basale:
• It is the deepest layer of the epidermis.
• It is composed of single layer of cuboidal or
columnor keratinocytes.
• Stem cells undergo cell division to produce new
keratinocytes.
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THE DERMIS
• Second deeper layer of the skin is dermis.
• It is composed of mainly connective tissue.
• Blood vessels, nerves, glands and hair follicle are
embedded in the dermis tissue.
• The dermis can be divided into:
1. Papillary region
2. Reticular region
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THE DERMIS
• The papillary region makes up to the 1/5th thickness
of total layer.
• It consist of areolar connective tissue containing fine
elastic fibers.
• Its surface area is greatly increased by small,
fingerlike structure called as dermal papillae.
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THE DERMIS
• The reticular region which is attached to thesubcutaneous layer, consists of dense irregular tissuecontaining fibroblast, bundles of collagen and someelastic fibers.
• A few adipose cells, hair follicles, nerves, sebaceous(oil) glands and sweat glands are present in thereticular region.
• The combination of collagen and elastic fibers in thereticular region provides the skin with strength,extensibility and elasticity.
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ACCESSORY STRUCTURE OF
THE SKIN
• The accessory structure of the skin
includes
1. Hairs: Protects the body.
2. Skin glands: Regulate body temperature
3. Nails: Protects the body
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HAIRS (PILI)
Hair anatomy:
- composed of dead columns of keratinized cells.
- shaft: is the superficial portion of hair.
- root: below the surface in the dermis.
• Shaft and root are composed of three layers: inner medulla, middle cortex and outer cuticle.
• Inner medulla has 2-3 rows of polyhedral cells where pigment is located.
• Cortex is major portion of shaft.
• Cuticle is scaly and heavily keratinized (shingles).
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HAIR
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HAIR
• Cuticle of the hair:• Surrounding the root hair is the hair follicle which is made up of
external root sheath and internal root sheath .
• Together these are referred as epithelial root sheath.
• The dense dermis surrounding the hair follicle is called as dermal root sheath.
• The base of each hair follicle is called as dermal root sheath.
• The base of each hair follicle is an anion shaped structure called bulb.
• The bulb contains nipple structure called as papilla of the hair contains many blood vessels that nourish the growing hair follicle.
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HAIR
• Cuticle of the hair:
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SKIN GLANDSGlands:Two types of glands exist in the integument.
- Sebaceous glands (oil glands)- Sudoriferous glands (sweat glands)
Sebaceous glands: (oil or holocrine glands)- connected to hair follicle- not found on palms and soles of feet- secretes sebum (fats, cholesterol andproteins
- keep hair from drying out, keeps skin moist- whiteheads, blackheads and acne
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SKIN GLANDS
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SKIN GLANDS
• Whitehead: When the trapped sebum and bacteria stay below the skin surface, a whitehead is formed.
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SKIN GLANDS• Blackhead: A blackhead occurs when the trapped
sebum and bacteria partially open to the surface and
turn black due to melanin, the skin's pigment.
Blackheads can last for a long time because the
contents very slowly drain to the surface.
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SKIN GLANDS
Sudoriferous glands: ( Sweat gland)
exocrine glands
- millions located throughout the skin
- It has two types:
1. Eccrine sweat gland
2. Apocrine sweat gland
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SKIN GLANDS
Eccarine :more common (merocrine)
- originate in subQ layer
- duct empties on skin surface
- palms and soles of feet
- sweat is watery (99% H20)
- sweating regulated by
-sympathetic nervous system
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SKIN GLANDS- Apocrine: axillary and pubic region
- duct empties onto hair follicle
- viscous fluid
- causes body odor (“b-o “) when
bacteria break it down
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SKIN GLANDS
Ceruminous glands: located in ear only
- modified apocrine glands
- originate in Sub Q layer
- ducts open onto EAM.
- produces cerumen (ear wax) : brown
sticky substance that prevents foreign
material from entering.
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THANK YOU