Integumentary System

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Lecture 4

• Integumentary System

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Integumentary System

• Consists of
• Skin (Epidermis Dermis)
• Accessory structures
• Hair
• Nails
• Glands
• Functions
• Protection
• Sensation
• Temperature regulation
• Vitamin D production
• Excretion

Fig. 5.1
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Epidermis and Dermis
Fig. 5.2
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Epidermal Cells

• Cell types
• Keratinocytes Produce keratin for strength
• Melanocytes Contribute to skin color (pigment
  melanin)
• 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 Strata

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

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Epidermal Layers and Keratinization
Fig. 5.4
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Dermis

• Structural strength
• Two layers
• Deeper layer - dense connective tissue stretch
  marks (striae)
• Superficial layer underneath epidermis - loose
  connective tissue

Fig. 5.1
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Hypodermis

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

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Accessory Skin Structures

• 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
• Mammary glands
• Nails

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Hair (Pilus) Structure

• 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

Fig. 5.6a
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Nails

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

Fig. 5.8
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Oil and Sweat Glands

• Sebaceous glands
• Produce sebum
• Oils hair and skin surface
• Sudoriferous glands (sweat)
• Most commonly found in palms, soles and forehead
• Also found in axillae (arm pit), genitalia,
  around anus
• Ceruminous glands (cerumen or ear wax)
• Mammary glands

Fig. 5.7
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Points to Remember

• Two components to integumentary system
• Skin (epidermis dermis)
• Accessory structures (hair, nails and glands)
• Keratinization (accumulation of keratin) produces
  upper layer of cells of epidermis, hair and nails
• Two types of glands in skin
• Sebaceous (oily)
• Sudiferous (watery)

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Questions?