Integumentary System

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Chapter 5
Integumentary System
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Functions

• Protection
• Abrasion
• Microorganisms
• UV light
• Hair protects
• Nails protect digits from damage

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Functions

• Sensations
• Free nerve endings
• Merkels disk
• Hair follicle receptor
• Pacinian corpuscle
• Meissners corpuscles
• Ruffinis end organ

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Functions

• Temperature regulation
• Radiation
• Conduction
• Evaporation
• Conduction

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Functions

• Vitamin D Production
• Exposure of skin to UV radiation
• Precursor molecule produced in skin
• Modified in liver and kidney.

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Functions

• Excretion
• Water
• Salt
• Urea
• Uric Acid
• Ammonia

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Hypodermis

• Skin rests on this, but not a part
• Consists of loose connective tissue
• Types of cells
• Fibroblasts
• Adipose cells
• Macrophages
• Also called
• Subcutaneous tissue
• Superficial fascia

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Layers of the Skin

• Dermis
• Structural strength
• Cleavage lines
• Two layers
• Epidermis
• Avascular
• Cells
• Layers or strata

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Dermal Layer
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Epidermal Layer
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Epidermal Layers

• Stratum Basale
• Deepest portion of epidermis and single layer
• High mitotic activity and cells become
  keratinized
• Stratum Spinosum
• Limited cell division
• Stratum Granulosum
• In superficial layers nucleus and other
  organelles degenerate and cell dies

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Epidermal Layers

• Stratum Lucidum
• Thin, clear zone
• Stratum Corneum
• Most superficial and consists of cornified cells

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Epidermal Cells

• Cell types
• Keratinocytes Produce keratin for strength
• Melanocytes Contribute to skin color
• Langerhans cells Part of the immune system
• Merkels cells Detect light touch and pressure
• Desquamate Older cells slough off
• Keratinization Cells die and produce outer layer
  that resists abrasion and forms permeability
  layer

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Epidermal Cells
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Coloration

• Determined by 3 factors
• Pigments
• Melanin Provides for protection against UV light
• Albinism Deficiency or absence of pigment
• Carotene Yellow pigment
• Blood circulating through the skin
• Imparts reddish hue and increases during
  blushing, anger, inflammation
• Cyanosis Blue color caused by decrease in blood
  oxygen content
• Thickness of stratum corneum

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Epidermal Derivatives or Accessory Sturctures

• Hair
• Found everywhere on human body except palms,
  soles, lips, nipples, parts of external
  genitalia, and distal segments of fingers and
  toes
• Glands
• Sebaceous or oil glands
• Sudoriferous or sweat glands
• Ceruminous glands
• Mammary glands
• Nails

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Hair

• Composed of shaft and root
• Shaft protrudes above skin surface
• Root located below surface and base forms the
  hair bulb
• Has 3 concentric layers
• Medulla Central axis
• Cortex Forms bulk of hair
• Cuticle Forms hair surface

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Hair

• Types of hair
• Lanugo
• Vellus hair
• Terminal hair
• Determinant Hair
• Indeterminant Hair

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Hair

• Hair Growth
• Growth stage
• Cells of matrix differentiate
• Cells become keratinized and die
• Hair follicle shortens and holds hair in place
• Resting stage
• Followed by new growth phase
• Hair falls out of the follicle
• New hair replaces the old.

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Sebaceous Glands

• Sebaceous glands
• Produce sebum
• Oils hair and skin surface

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Sweat Glands

• Sudoriferous glands
• Merocrine or eccrine
• Most common
• Numerous in palms and soles
• Apocrine
• Found in axillae, genitalia, around anus

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Other Glands

• Ceruminous glands
• Modified merocrine glands
• Produce cerumen, earwax
• Mammary glands
• Modified apocrine glands
• Produce milk

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Nails

• Anatomy
• Nail root proximally
• Nail body distally Eponychium or cuticle
• Growth
• Grow continuously unlike hair

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Nails