skin and subcutaneous tissue

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SKIN AND SUBCUTANEOUS TISSUE

• M . Shahzad khalid
• Directorate of Medical Sciences

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COMPOSITION OF SKIN

• Complex structure made up of
• EPITHELIUM
• CONNECTIVE TISSUE
• OUTER LAYER EPIDERMIS
• INNER LAYER DERMIS

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SURFACE AREA OF SKIN

• A W x H x 71.84
• where
• A Area in Square meters
• W Weight of individual in Kg
• H Height of individual in cm
• It is usually 1.5 to 2 square meters.

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FUNCTIONS OF SKIN

1. SENSATION
2. PROTECTION
3. TEMPERATURE REGULATION
4. CONTOL OF WATER OUTPUT
5. ABSORPTION
6. SECRETIONS
7. EXCRETION
8. SYNTHESIS OF VITAMIN D
9. STORAGE OF FAT
10. Ph REGULATION
11. REPAIR AFTER INJURY TRAUMA
12. SOCIAL COMMUNICATION

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EPIDERMIS

• Avascular keratinized epithelium
• Wear tear occurs from basal cells
• Mitotic activity (growth)

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LAYERS OF EPIDERMIS

• Stratum corneum
• Stratum lucidum
• Stratum granulosum
• Stratum spinosum
• Stratum basale

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LAYERS OF EPIDERMIS
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DERMIS

• Lamina propria of mucous membrane
• Dermis contains
• Nerves
• Lymphatics
• Blood vessels

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• Epidermis dermis collectively form CUTANEOUS
  MEMBRANE
• Beneath cutaneous membrane, there is subcutaneous
  tissue called SUPERFICIAL FASCIA
• Collagen fibres connect dermis with fascia,
  prevents loosening of skin

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THICKNESS OF SKIN

• Depends on
• Horny layer of epidermis
• Horny layer of dermis
• For example
• Skin of palms soles
• Skin of back
• NOTE dermis tends to be thicker on extensor
  surface than flexor surface

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COLOUR OF SKIN

• Carotene
• Blood
• Melanin
• Melanocytes
• These cells are scattered beneath basal layer
  of epidermis and some are found in dermis

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CHARACTERISTICS OF SKIN

• Finger Prints
• Creases
• Langers Lines

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Creases of skin
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Langers Lines
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SKIN APPENDAGES

• Hair
• Nails
• Cutaneous glands

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HAIR

• Elastic keratinous threads
• Developed from epidermis
• Absent on palms, soles, urogenital openings
• Consists of 2 parts
• Shaft
• Hair bulb

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STRUCTURE OF HAIR
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HAIR GROWTH

• Hair growth
• Transitional phase
• Rest elimination of old hair
• Growth

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NAILS

• Nail plate
• Nail root
• Nail folds
• Nail bed
• Nail matrix
• Hyponychium
• Eponychium

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STRUCTURE OF NAIL
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CUTANEOUS GLANDS

• Sebaceous glands
• Holocrine glands present on body except palms
  soles
• Mebomian glands of eyelids
• Secret sebum
• Increase with androgenic activity

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Sebaceous glands
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CUTANEOUS GLANDS

• Sweat glands
• Present on whole body except nail beds, margin of
  lips
• Numerous on palms, forehead soles called
  Merocrine glands, producing clear watery
  secretions
• Large glands are present in axilla, areola,
  called apocrine glands, producing thicker
  secretions

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Sweat glands
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TYPES OF GLANDS

• Exocrine Glands secrete their products through
  directly into the blood stream and lack a duct
  system.
• Endocrine Glands secrete their products through
  a duct or directly to the surface.

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EXOCRINE GLANDS

• Classification on the basis of structure
• Apocrine glands  a portion of the
  secreting cell's body is lost during secretion
• Holocrine glands  the entire cell disintegrates
  to secrete its substances
• Merocrine glands  cells secrete their substances
  by exocytosis

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EXOCRINE GLANDS

• Classification on the basis of secretion
• Serous glands  secrete thin watery secretion
• Mucous glands  secrete thick viscous
  secretions
• Sebaceous glands  secrete thick oily
  secretion, also known as oil glands.

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VASCULAR SUPPLY

• Subcutaneous Arteries
• Subcutaneous Veins
• Subcutaneous Lymphatics
• Subcutaneous Nerves

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SUPERFICIAL FASCIA

• Formed by loose connective tissue adipose
  tissue
• Thickness varies in different regions of body
• Fibrous layer, firmly attached to dermis deep
  tissues
• Functions as a cushion, space filler storage
  house

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DEEP FASCIA

• Real fascia
• Connective tissue
• Binds compartments
• Forms partitions isolate the structures

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