166
UNIT 2
Covering, Support, and Movement of the Body
5
Second-degree burns
injure the epidermis and the upper
region of the dermis. Symptoms mimic those of first-degree
burns, but blisters also appear. Te burned area is red and pain-
ful, but skin regeneration occurs with little or no scarring within
three to four weeks if care is taken to prevent infection. First-
and second-degree burns are referred to as
partial-thickness
burns
(Figure 5.10a)
.
Tird-degree burns
are
full-thickness burns
, involving the
entire thickness of the skin (Figure 5.10b). Te burned area ap-
pears gray-white, cherry red, or blackened, and initially there is
little or no edema. Since the nerve endings have been destroyed,
the burned area is not painful. Although skin might eventually
regenerate by proliferating epithelial cells at the edges of the
burn or stem cells in hair follicles, it is usually impossible to
wait that long because of fluid loss and infection. Skin gra±ing
is advised.
In general, burns are considered critical if any of the follow-
ing conditions exists:
Over 25% of the body has second-degree burns
Over 10% of the body has third-degree burns
Tere are third-degree burns of the face, hands, or feet
Facial burns introduce the possibility of burned respiratory
passageways, which can swell and cause suffocation. Burns at
joints are also troublesome because scar tissue can severely limit
joint mobility.
Treating Burns
²o prepare a burned area for a skin gra±, the
eschar
(es
9
kar),
or burned skin, must first be debrided (removed). ²o prevent
infection and fluid loss, the area is then flooded with antibiotics
and covered temporarily with a synthetic membrane, animal
(pig) skin, cadaver skin, or “living bandage” made from the thin
amniotic sac membrane that surrounds a fetus. Ten healthy
skin is transplanted to the burned site. Unless the gra± is taken
from the patient (an autogra±), however, there is a good chance
that the patient’s immune system will reject it (see p. 790 in
Chapter 21). Even if the gra± “takes,” extensive scar tissue o±en
forms in the burned areas.
An exciting technique eliminates many of the traditional
problems of skin gra±ing and rejection. Synthetic skin—a sili-
cone “epidermis” bound to a spongy “dermal” layer composed
of collagen and ground cartilage—is applied to the debrided
area. In time, the patient’s own dermal tissue absorbs and re-
places the artificial one. Ten the silicone sheet is peeled off and
replaced with a network of epidermal cells cultured from the
patient’s own skin. Te body does not reject this artificial skin,
which saves lives and results in minimal scarring. However, it is
more likely to become infected than is an autogra±.
Check Your Understanding
25.
Which type of skin cancer develops from the youngest
epidermal cells?
26.
What name is given to the rule for recognizing the signs of
melanoma?
(a) Skin bearing partial thickness burn (1st- and
2nd-degree burns)
(b) Skin bearing full thickness burn (3rd-degree
burn)
1st-degree burn
2nd-degree burn
3rd-degree burn
Figure 5.10
Partial thickness and full thickness burns.
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