Integumentary System
Skin
The Body’s Protection
Skin: Two principle layers
• Epidermis
• Dermis
Epidermis
• A. Epidermis- Outer, thinner portion of the
skin
– 1. Composed of both dead and living cells.
• a. Keratin- protein in dead epidermal cells that helps
waterproof and protect living layers beneath it.
• b. Melanin- Melanin is a cell pigment that colors the
skin and protects the cell from solar radiation.
– 2. Epidermal ridges- “fingerprints” and
“footprints” – Important for gripping because
they increase friction. They are also used to
identify individuals.
Dermis
• Dermis- The inner, thicker portion of the
skin.
– 1. Varies in thickness- 3-4 mm on the palms of
the hands and soles of the feet. 0.5mm
thickness on the surface of the eye.
– 2. Adaptations of the Dermis:
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a. Blood vessels
b. Nerves
c. Nerve endings
d. Sweat glands
e. Oil glands
f. Fat deposits- cushion, insulate, store food
g. Hair follicles
Memorize p. 934!!!
Skin: Vital Functions
Homeostasismaintaining equilibrium
1. Heat responsecapillaries in the dermis
dilate, blood flow
increases, heat is lost
by radiation, and glands
in the dermis produce
sweat and, as the sweat
evaporates, the body
cools.
Skin: Vital functions
• 2. Cold responseblood vessels in
the skin constrict
and heat is
conserved.
Skin: Vital functions
• 3. First line of defense- serves as a
protective layer to underlying tissues. Skin
protects the body from physical and
chemical damage and from the invasion of
microbes.
Skin: Vital Functions
• 4. Sense organnerve cells in the
dermis receive stimuli
from the environment
and relay information
about pressure, pain,
and temperature.
(We’ve all stepped on
a sharp object or
have been
sunburned.)
Review Video
• YouTube – National Geographic What is
Skin?
Skin: Injury
• A. Scrapes- the epidermis undergoes
mitosis and fills in the gap left by the
abrasion.
• B. Injury of the dermis- painful and
bleeding usually occurs
Burns
• Burns- exposure to sun, heat, or chemicals
– 1. First degree- redness and mild pain; death
of epidermal cells.
– 2. Second degree- damage to the dermis,
blistering may occur.
3. Third degree- destroys epidermis and
dermis; skin function is lost and regrowth of
skin is slow with much scarring. Skin grafts
may be required.
Aging/Wrinkles- the cause:
• 1. Skin becomes less elastic with age
• 2. Oil glands produce less oil resulting in
dry skin
• 3. Prolonged exposure to ultraviolet rays
can damage skin cells and accelerate the
aging process
• 4. Smoking- ties up oxygen to facial tissue
Acne
• Bacterial infection of the oil glands of
the skin
How long does skin last?
• The entire epidermal layer is replaced
every 28 days.
World Records
World’s Strechiest Skin
Garry Turner, of Caistor, Lincolnshire,
England, stretched the skin of his
stomach to a distended length of 15.8
cm (6.25 in) on the set of Guinness
World Records: Primetime in Los
Angeles, California, USA, on October
29, 1999.
Garry has a rare medical condition
called Elhers-Danlos Syndrome, a
disorder of the connective tissues
affecting the skin, ligaments and
internal organs. With this condition,
the collagen that strengthens the skin
and determines its elasticity becomes
defective, resulting in, among other
things, a loosening of the skin, and
"hypermobility" of the joints. In more
serious cases, it can cause the fatal
collapse or rupturing of blood vessels.
World’s Longest Fingernails
The current world recorder holder for
the longest fingernails is Lee Redmond
(Utah). Ms. Redmond, who hasn’t cut
her nails since 1979, has grown and
carefully manicured them to reach a
total length of 7 m 51.3 cm (24 ft 7.8 in).
Skin
Problems &
Disorders
*Some of these images may not be suitable for
the squeamish.*
Acne
Skin Cancer- Basal Cell Carcinoma
Basal cell carcinoma is the
most common type of skin
cancer. It usually occurs
on areas of the skin that
have been in the sun, most
often the nose. Often this
cancer appears as a small
raised bump that has a
smooth, pearly
appearance. Another type
looks like a scar and is flat
and firm to the touch.
Basal cell carcinoma may
spread to tissues around
the cancer, but it usually
does not spread to other
parts of the body.
Skin Cancer- Squamous Cell Carcinoma
Squamous cell
carcinoma occurs on
areas of the skin that
have been in the sun,
such as the ears, lower
lip, and the back of the
hands. Squamous cell
carcinoma may also
appear on areas of the
skin that have been
burned or exposed to
chemicals or radiation.
Often this cancer
appears as a firm red
bump. Sometimes the
tumor may feel scaly or
bleed or develop a
crust. Squamous cell
tumors may spread to
nearby lymph nodes.
Skin Cancer- Melanoma
Melanoma is a form of
cancer that begins in
melanocytes (cells that
make the pigment
melanin). It may begin in a
mole (skin melanoma),
but can also begin in
other pigmented tissues,
such as in the eye or in
the intestines.
Melanomas, the most
dangerous form of skin
cancer, are responsible
for the deaths of 20
Americans each day.
Check Your Moles!!!
Chicken Pox & Shingles (Herpes zoster)
Warts
Plantar wart
Warts are a skin growth that is
caused by a virus called the
human papilloma virus. These
viruses enter the skin and cause
a wart to grow. They are usually
the same color as skin, and can
be flat, raised or smooth. Most
warts are harmless but some can
be cancerous. As it is caused by a
virus, warts are contagious to
others who may be susceptible to
the same virus. Therefore care
needs to be taken when coming
into contact with another person.
Genital wart
Common warts
Carbuncle
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A skin infection that often
involves a group of hair follicles.
The infected material forms a
lump, called mass, which occurs
deep in the skin.
A carbuncle is a swollen lump or
mass under the skin. It may be
the size of a pea or as large as a
golf ball. The carbuncle may be
red and irritated and might hurt
when you touch it.
It may also: grow very fast, have
a white or yellow center
(pustule), weep, ooze, or crust,
spread to other skin areas
Most carbuncles are caused by
the bacteria Staphylococcus
aureus.
Vitiligo
(vit-ih-LI-go)
A skin condition in
which there is loss of pigment (color)
from areas of skin, resulting in irregular
white patches that feel like normal skin.
Vitiligo affects both genders and all
races, but is more noticeable in people
with darker skin.
Gangrene
Gangrene is a medical term used to describe the necrosis (death) of
tissue. It develops when the blood supply is cut off to the affected
part as a result of various processes, such as infection, vascular
(pertaining to blood vessels) disease, or trauma. Gangrene can
involve any part of the body; the most common sites include the
toes, fingers, feet, and hands.
Quiz over your notes
tomorrow!!!