The Integumentary SystemTHE DERMIS

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Dense connective tissue of varying thickness

Two layers:◦ Papillary (upper)◦ Reticular (lower)

The Dermis and its layers

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Uneven Peg-like projections called dermal papillae

lie at the dermal-epidermal junction◦ This layer provides nutrients to the epidermis◦ Houses pain and touch receptors

◦ Forms fingerprints (on hands and feet): increases friction and gripping sweat pores leave identifying “sweat films” patterns are genetically determined

Papillary Layer

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Deepest skin layer; makes up 80% of dermis

Collagen and elastic fibers provide strength and elasticity ◦ This is the layer that looses elasticity = WRINKLES!

Contains blood vessels, sweat and oil glands

Lamellar corpuscles- sense deep pressure

Reticular layer

Figure 4.5 Light micrograph of the two regions of the dermis (100×).

Epidermis

Dermis

Papillarylayer

Reticularlayer

Figure 4.3 Skin structure.

Dermal papillae

Hair shaft

Pore

Appendages of skin• Eccrine sweat gland• Arrector pili muscle• Sebaceous (oil) gland• Hair follicle• Hair root

Cutaneous vascular plexus

Adipose tissue

Epidermis

Dermis

Papillarylayer

Reticularlayer

Hypodermis(subcutaneoustissue)

Nervous structures• Sensory nerve fiber• Lamellar corpuscle• Hair follicle receptor (root hair plexus)

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Three pigments contribute to skin color:1. Melanin Yellow, reddish brown, or black pigments

2. Carotene Orange-yellow pigment (deposited in the skin)

3. Hemoglobin Red coloring from blood cells in dermal capillaries Oxygen content determines the extent of red

coloring Lighter skin shows this more so than darker

Skin Color

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Redness (erythema)—due to embarrassment, inflammation, hypertension, fever, or allergy

Pallor (blanching)—due to emotional stress (such as fear), anemia, low blood pressure, impaired blood flow to an area

Jaundice (yellowing)—liver disorders create excess bile deposition in tissues

Bruises (black and blue marks)—hematomas (blood clots)

Alterations in Skin Color