The Integumentary System

THE DERMISPages 116-119

Dermis is made of dense connective tissue Varies in thickness throughout the body

Has two layers:◦ Papillary◦ Reticular

The Dermis and its layers

© 2015 Pearson Education, Inc.

Uneven Contains projections called dermal

papillae ◦ contain capillary loops that furnish nutrients to

the epidermis◦ houses pain receptors (free nerve endings) and

touch receptors◦ On hands and feet forms fingerprints:

Definite patterns that increase friction and gripping Sweat pores leave identifying “sweat films” Patterns are genetically determined

Papillary Layer (upper layer)

© 2015 Pearson Education, Inc.

Makes up 80% of dermis Collagen and elastic fibers

◦ Strength ◦ Elasticity

Blood vessels maintain body temperature Sweat and oil glands Lamellar corpuscles- sensory receptors

◦ Send sensory information about deep pressure

(Remember the Merkel cells are responsible for light pressure and are found in the epiderm-derm jx)

Reticular layer (deepest skin layer)

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

Epidermis

Dermis

Papillarylayer

Reticularlayer

© 2015 Pearson Education, Inc.

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

2. Carotene Orange-yellow pigment from some vegetables

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

coloring

Skin Color

© 2015 Pearson Education, Inc.

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 disorder

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

Alterations in Skin Color

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)