1. Integumentary System Accessories

2. Hair

3. Hair Functions Helping to maintain warmth
Cold stimulates muscles (arrector pili) to erect hairs which traps warm body heat next to skin
Alerting the body to presence of insects on the skin
root hair plexus (sensory nerve endings) wraps around each hair bulb
Bending a hair stimulates these endings
hairs act as sensitive touch receptors
Guarding the scalp against physical trauma, heat loss, and sunlight

4. Hair Distribution & Types
Hair is found over the entire skin surface except:
Palms, soles, and lips
Nipples and portions of the external genitalia
Hair Types:
Vellus –
pale, fine body hair
found in children and the adult female
Terminal –
coarse, long hair of eyebrows, scalp, axillary, and pubic regions

5. Hair Thinning and Baldness
Alopecia – hair thinning in both sexes
True, or frank, baldness
Genetically determined and sex-influenced condition
Male pattern baldness – caused by follicular response to DHT

6. Hair strands of dead keratinized cells
Has hard keratin which is tougher and more durable than soft keratin of the skin
produced by hair follicles
Color comes from melanocytes at the base of the hair

7. Hair Follicle
Root sheath extending from the epidermal surface into the dermis
4 layers thick (from inside out):
Internal epithelial root sheath
External epithelial root sheath
Glassy membrane
Connective tissue root sheaths
Deep end of follicle forms a hair papilla where shaft grows out of

8. Hair Follicle
Figure 5.5c

9. Hair Shaft Consists of 3 parts Medulla- middle column
Cortex- surrounds medulla, contains color (pigment granules)
Cuticle- outermost layer, made of overlapping cells (scales)

10. Glands

11. Sweat Glands Eccrine sweat glands – Apocrine sweat glands –
found in palms, soles of the feet, and forehead
Apocrine sweat glands –
found in axillary (armpit) and anogenital areas
Ceruminous glands –
modified apocrine glands
in external ear canal
secretes cerumen (ear wax)
Mammary glands –
specialized sweat glands that secrete milk

12. Sebaceous Glands Found all over the body
Soften skin when stimulated by hormones
Secrete an oily secretion called sebum
Found near hair follicles

13. Fingernails

14. Structure of a Nail
Scalelike modification of the epidermis on the distal, dorsal surface of fingers and toes
Figure 5.6