Dermis & Accessory Structures (Hair, Glands, Nails)

Dermis Beneath epidermis The location for blood vessels, nerves, glands, hair follicles, and arrector pili (smooth muscle; contractions produce “goose bumps”)

Fig. 5.2 Papillae = nipples

Dermis - Structure Papillary region - upper layer - 20% 4/15/2017 Dermis - Structure Papillary region - upper layer - 20% Areolar connective tissue Reticular region - 80% Underneath the papillary layer Dense irregular connective tissue Fibers tolerate limited stretching; “stretch marks” can appear (not clear boundary between the two layers)

Hair Functions: Protection Insulation Sensation 4/15/2017 Hair Functions: Protection Insulation Sensation Secondary sexual characteristic to attract mates Rate of growth & replacement affected by: heredity, diet, illness, fever, blood loss, surgery, drugs, chemotherapy, etc.

Hair Cont. Hair Follicle – site of hair origin Hair: 4/15/2017 Hair Follicle – site of hair origin Hair: Shaft (above skin surface) Root & bulb (underneath skin surface) Bulb contains matrix – dividing layer; builds hair Hair is made out of keratin brown, black - melanin deposited from the matrix of the bulb into the shaft red, blond - variants of melanin with iron, sulfur in the molecule grey - some loss of melanocytes reduces melanin deposition

Nails tightly packed, hard, keratinized cells 4/15/2017 Nails tightly packed, hard, keratinized cells nail matrix - site of nail growth; under root of nail 1 mm/week in fingers; slower in toes Nail matrix - transforms normal skin cells into nail cells which push forward

Sebaceous (Oil) Glands 4/15/2017 Sebaceous (Oil) Glands connected to hair follicles in the dermis secrete sebum (oil) keeps hair from drying prevents water evaporation from skin keeps skin soft, supple inhibits growth of many bacteria Sebum = fats, cholesterol, proteins, inorganic salts busy at puberty

Sudoriferous (Sweat) Glands Eccrine (merocrine) glands: In the skin that covers most parts of our bodies Produce a thin, watery liquid that contains salt and small amounts of other bodily wastes Help cool the body through the process of evaporation Apocrine glands: In the skin of the armpits, around nipples, and in the groin Produce a thicker salty and acidic solution Produce “body odor” (in contact with bacteria) Become active when a person reaches puberty Secrete more during emotional stress & sexual arousal

Apocrine & Eccrine Sweat Glands

Other Specialized Integumentary Glands 4/15/2017 Other Specialized Integumentary Glands Ceruminous glands – together with oil glands produce ear wax protect against foreign particles & small insects

Burns