Chapter 5 Skin and the Integumentary System

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Chapter 5Skin and the Integumentary System

• Composed of several tissues
• Maintains homeostasis
• Protective covering
• Retards water loss
• Regulates body temperature
• Houses sensory receptors
• Contains immune system cells
• Synthesizes chemicals
• Excretes small amounts of waste

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Layers of Skin

• Epidermis
• Dermis
• Subcutaneous layer

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Epidermis

• lacks blood vessels

• keratinized

• thickest on palms and soles (0.8-1.4mm)

• melanocytes provide melanin

• stratified squamous

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Dermis

• on average 1.0-2.0mm thick

• dermal papillae

• binds epidermis to
• underlying tissues

• irregular dense
• connective tissue

• nerve cell processes

• blood vessels

• hair follicles

• glands

• arrector pili

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Subcutaneous Layer

• hypodermis

• loose connective tissue

• adipose tissue

• insulates

• major blood vessels

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Hair Follicles

• epidermal cells

• extends into dermis

• hair root

• hair shaft

• hair papilla

• melanin

• arrector pili muscle
• lanugo
• absent on lips, palms,
• soles

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Nails

• protective coverings

• nail plate
• (body)

_____Free Edge

• nail bed

Cuticle_________

• lunula
• root

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Sweat Glands

• sudoriferous glands

• widespread in skin

• deep dermis or
• hypodermis

• eccrine glands

• apocrine glands

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Sebaceous Glands

• usually associated with hair follicles

• secrete sebum

• absent on palms and soles

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Regulation of Body Temperature
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Problems in Temperature Regulation
Hyperthermia abnormally high body temperature
Hypothermia abnormally low body temperature
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Skin Color

• Physiological Factors
• dilation of dermal blood vessels
• constriction of dermal blood vessels
• carotene
• jaundice

• Genetic Factors
• varying amounts of melanin
• varying size of melanin granules
• albinos lack melanin

• Environmental Factors
• sunlight
• UV light from sunlamps

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Clinical Application
Acne Vulgaris

• most common skin disorder
• sebum and epithelial cells clog glands
• produces whiteheads and blackheads (comedones)
• anaerobic bacteria trigger inflammation (pimple)
• largely hormonally induced
• androgens stimulate sebum production
• treatments include antibiotics, topical creams,
  birth control pills

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