Chapter 5: Integumentary Sys.

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Chapter 5 Integumentary Sys.

• Skin
• Accessory Structures
• - hair, nails, sweat glands, sebaceous glands

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Functions

• Protection- abrasion, UV, pathogens, dehydration
• Sensation
• Vitamin D production
• Temperature regulation
• Excretion

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Structure

• Epidermis- stratified squamous epithelial tissue
• Dermis- dense connective tissue
• Hypodermis- subcutaneous tissue
• consisting of half of the stored body fat.
• Used to estimate total body fat.

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Dermis

• 10-20 times thicker than epidermis
• Dense collagenous connective tissue
• It also has elastic fibers
• Fibroblasts, fat cells (fewer than hypodermis),
  and macrophages
• Collagen orientated in specific pattern to resist
  stretching

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Fig. 5.2
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Dermis

• Upper surface dermal papillae finger and foot
  prints
• Blood vessels and nerve ending, receptors
• Provide friction

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Epidermis

• Stratified squamous
• Constant shedding of the epidermis
• Stratum basale- embryonic cells
• Stratum corneum
• Top kertinized dead cells
• Callus
• Coated and surrounded by lipids to prevent water
  loss

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Problems in skin

• Epidermis
• - Dandruff- keratinization 2-3x normal rate
• Dermis
• - Wrinkles- reduction in collagen and elastin

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Skin color

• Melanocytes produce melanin (pigment)
• Stored in melanosomes
• Phagocytized into epithelial cells

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Fig. 5.4
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Variations in color

• Number of melanocytes same
• Amount, kind, distribution of melanin
• Albinism- lack of melanin
• Dark pigment in dermis- bluing effect
• - bruises, tattoos

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Fig. 5.5
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Hair

• Shaft
• Medulla, cortex and cuticle
• Hair follicle
• Extension of epidermis into dermis
• Important in tissue repair
• Hair bulb
• Produces hair
• Cyclic
• Eye lashes 30 days growth and 105 days rest
• Hair 3 years growth and 1-2 years rest
• Muscle arrector pili (smooth)

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Fig. 5.6
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Nails

• Thin plate of dead keratinized cells
• Visible part body
• Part covered by skin root
• Nail matrix cells production occurs
• No resting stage grows continuously

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Glands

• Sebaceous glands
• Simple branched acinar glands
• Connected superficially to the hair follicle
• Produces sebum
• Lubrication
• Prevention of drying

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Glands

• Sweat glands
• Merocrine simple coiled glands with ducts
  opening on to the surface of the skin
• Apocrine simple coiled tubular glands
• open into hair follicle only in the axillae and
  genitalia
• Produces thick organic substance
• Influenced by hormones

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Physiology

• Protection
• Water loss by acting as lipid barrier
• Acidic environment to deter microbial growth
• Stratified prevent damage due to abrasions
• Melanin to absorb UV
• Sensation Receptors
• Vit D production
• Temperature regulation
• Excretion

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Fig. 5a