Integumentary system part 2 - accessory organs, healing of cuts, burns

1. Accessory
Organs of
the Skin

2. Hair Function and Distribution
• Hair is distributed over the entire skin
surface except:
• Palms, soles, and lips
• Nipples and portions of the external
genitalia

3. Hair Follicle
• Individual hairs develop from cells at the base of the
hair follicle, an invagination of the lower epidermis that
dips down into the dermis
• As new cells are formed, old cells are pushed outward
and become keratinized, forming the hair shaft
• A bundle of smooth muscle cells, called the arrector
pili muscle, is attached to each hair follicle
• Hair color is determined by genetics; melanin from
melanocytes is responsible for most hair colors, but
red hair also contains the pigment trichosiderin

4. Hair Function and Distribution
• Functions of hair include:
• Helping to maintain warmth
• Alerting the body to presence of insects on
the skin
• Guarding the scalp against physical
trauma, heat loss, and sunlight

5. Sebaceous Glands (Oil Glands)
• Simple ~alveolar
glands found all over
the body
• Soften skin when
stimulated by
hormones
• Secrete an oily
secretion called
sebum

6. Sweat Glands
• Different types prevent overheating of the body;
secrete cerumen~ and milk
• Eccrine sweat glands – found in palms, soles of the
feet, and forehead. Respond to body temperature
• Apocrine sweat glands – found in axillary and
anogenital areas. Respond to body temperature,
stress, & sexual arrousal
• ~Eruminous glands – modified apocrine glands in
external ear canal that secrete cerumen (wax)
• ~Mammary glands – specialized sweat glands that
secrete milk

7. Structure of a Nail
• Scalelike modification of the epidermis on
the distal, dorsal surface of fingers and
toes
• Consist of epithelial cells overlying the nail
bed, with the lunula as the most actively
growing region of the nail root
• As new cells are produced, older ones are
pushed outward and become keratinized.

9. Functions of the Integumentary System:
Regulation of Body Temperature
• Body temperature regulation is
accomplished by:
• Dilation (cooling) and constriction
(warming) of dermal vessels
• Increasing sweat gland secretions to cool
the body
• Excessive cooling: inactivates sweat
glands, shivering

10. Healing of
Wounds &
Burns

11. Wounds
•Inflammation, in which blood vessels dilate and
become more permeable, causing tissues to become
red and swollen, is the body’s normal response to
injury.
•Superficial cuts are filled in by reproducing
epithelial cells.
•Deeper cuts are closed off by clots, covered by
scabs, and eventually filled in by fibroblasts, making
connective tissue. Blood vessels extend into the
area, injured tissues are replaced, and the scab falls
off.
•Large wounds leave scars and healing may be
accompanied by the formation of granulations.

13. Burns
• First-degree – only the epidermis is damaged
– Symptoms include localized redness, swelling, and
pain
• Second-degree – epidermis and upper regions
of dermis are damaged
– Symptoms mimic first degree burns, but blisters also
appear
• Third-degree – entire thickness of the skin is
damaged
– Burned area appears gray-white, cherry red, or black;
there is no initial edema or pain (since nerve endings
are destroyed)