Transcript 6. Skin - Dermis WEB

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
Dermis - Structure
Papillary region - upper Reticular region - 80%
layer - 20%
Underneath the papillary
Areolar connective tissue
layer
Dense irregular connective
tissue
Fibers tolerate limited
stretching; “stretch marks”
can appear
Hair
Functions:
Protection
Insulation
Sensation
Secondary sexual characteristic to attract mates
Hair Cont.
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
Nails
tightly packed, hard,
keratinized cells
nail matrix - site of nail
growth; under root of nail
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
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
Ceruminous glands – together with oil glands
produce ear wax
protect against foreign particles & small insects
Burns