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Accessory Structures of the Skin
A.
Nails
1.
Nails are protective coverings
over the ends of fingers and toes.
2.
Nails consist of a nail plate and
stratified squamous epithelial cells
overlying the nail bed, with the lunula
as the most actively growing region of
the nail root.
3.
As new cells are produced, older
ones are pushed outward and
become keratinized.
2
Fig06.04
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Lunula Nail bed Nail plate
3
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B.
Hair Follicles
1.
Hair can be found in nearly all
regions of the skin except palms,
soles, lips, nipples, and portions of
external genitalia.
2.
Each hair develops from cells
at the base of a tubelike depression
called the hair follicle. The dermis
contain the hair root.
3.
As new cells are formed, old cells are
pushed outward and become
keratinized, and die forming the hair
shaft.
4
Fig06.05a
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Hair shaft
Pore
Basement
membrane
Sebaceous
gland
Arrector pili
muscle
Hair root
(keratinized
cells)
Hair follicle
Eccrine
sweat gland
Region of
cell division
Dermal
blood
vessels
(a)
Fig06.05b
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Hair
follicle
Hair root
Adipose
tissue
Region of cell
division
©The McGraw-Hill Companies, Inc./Al Telser, photographer
(b)
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4.
A bundle of smooth muscle cells,
called the arrector pili muscle,
attaches to each hair follicle. These
muscles cause goose bumps when
cold or frightened.
5.
Hair color is determined by
genetics; melanin from melanocytes is
responsible for most hair colors.
Dark
hair has eumelanin while
blonde and
red hair have
pheomelanin.
6.
The arrector pili muscle attaches to
each hair follicle.
7
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C.
Sebaceous glands
1.
Sebaceous glands (holocrine
glands) are associated with hair
follicles and secrete sebum that
waterproofs and moisturizes the
hair shafts.
8
Fig06.07
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Hair follicle
Sebaceous gland
©The McGraw-Hill Companies, Inc./Al Telser, photographer
9
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D.
Sweat Glands
1.
Sweat glands (sudoriferous glands)
are either eccrine, which respond to
body temperature, or apocrine,
which respond to body temperature,
stress, and sexual arousal. The
secretions exit via a surface pore.
2.
Modified sweat glands, called
ceruminous glands, secrete wax in
the ear canal.
3.
Mammary glands, another modified
type of sweat glands, secrete milk.
10
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Regulation of Body Temperature
A.
Proper temperature regulation is vital to
maintaining metabolic reactions.
B. The skin plays a major role in temperature regulation
with the hypothalamus controlling it.
C.
Active cells, such as those of the heart and
skeletal muscle, produce heat.
11
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D.
E.
F.
Heat may be lost to the surroundings from
the skin through radiation.
The body responds to excessive heat by
dilation of dermal blood vessels and
sweating.
The body responds to excessive cooling
by constricting dermal blood vessels,
inactivating sweat glands, and shivering.
12
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Healing of Wounds
A.
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.
B.
Superficial cuts are filled in by reproducing
epithelial cells.
13
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C.
The blood clot and dried tissue fluids form a
scab.
D.
If the wound is deep, extensive production of
collagenous fibers may form an elevation above the
normal epidermal surface forming a scar.
E.
Large wounds leave scars and healing may be
accompanied by the formation of granulations.
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Decubitus Ulcer (Bed Sore)
Stage I Decubitus ulcer
• Skin is not broken
• Epidermis & dermis are intact
• Erythema that does not resolve within 30
minutes present
Stage II Decubitus Ulcer
• Skin is NOT intact
• Epidermis is damaged, dermis can be involved
• Skin can be blistered, cracked, & open with
erythema
• No necrotic or dead tissue present
• Wound bed is moist, pink, painful
Stage III Decubitus ulcer
• Full thickness skin loss
• Epidermis & dermis involved. May have
part of dermis left with necrosis
• May or may NOT be painful
• Possible drainage
Stage IV Decubitus ulcer
• Involves subcutaneous tissues – possibly fat,
muscle, & bone
• Can see pink healthy cells, necrotic tissue, &
eschar
• Wound can tunnel or have undermining in
skin surrounding wound
• Risks osteomyelitis
Do you think a Stage IV decubitus
Ulcer is painful?
• Yes or No
• The answer is both Yes and No
• Some patients will rate there pain as extreme
while others will not have much pain at all
because the ulcer has eaten through nervous
tissue
Stage IV Decubitus Ulcer
Bone
exposed
Stage IV Decubitus Ulcer
Stage IV Decubitus Ulcer
Conditions leading to decubitus
• Pressure leads to decreased blood flow &
nutrition resulting in tissue loss
• Excessively wet or dry skin (uribary or fecal
incontinence)
• Moving residents causing shearing (friction
across bed sheets causing skin tears in elderly)