Chapter 4
Overview
The integumentary system is a dynamic
continuous body covering composed
of:
• Blood vessels
• Connective tissue structures
• Glands
• Hair
• Nails
• Skin
Chapter 4 – The Skin and Its Parts
The Integumentary System
The skin has three
distinct layers: the
epidermis, the
dermis, and the
hypodermis (or
subcutaneous layer).
Chapter 4 – The Skin and Its Parts
The Integumentary System
Epidermis:
Outermost layer,
where new skin cells
are continually
produced
Chapter 4 – The Skin and Its Parts
The Integumentary System
Dermis:
Middle layer;
composed mostly of
connective tissue
Chapter 4 – The Skin and Its Parts
The Integumentary System
Hypodermis:
(also called the
subcutaneous layer)
Innermost layer,
composed of loosely
arranged elastic
fibers that anchor the
skin to underlying
tissue
Chapter 4 – The Skin and Its Parts
The Integumentary System
The four main functions of the integumentary
system are:
• Protection against environmental damage
• Heat regulation – maintain a constant internal
temperature
• Sensation – receiving stimuli from the
environment
• Waste excretion
Chapter 4 – The Skin and Its Parts
GLANDS
3 types of glands commonly found in the skin:
1. Ceruminous glands
• Produces a waxy secretion called
cerumen
• Found in the lining of the ear canal
2. Sebaceous glands
• Produce an oily secretion called sebum
• Secreted into hair follicles & moves to
the surface of the skin
3. Sweat glands
Chapter 4 – The Skin and Its Parts
SWEAT GLANDS
2 Types:
1. Apocrine sweat glands
 Secrete odorous sweat into the hair
follicles of the armpits, navel, and groin
regions
 Inactive until puberty
 Usually tapers off in the elderly
Chapter 4 – The Skin and Its Parts
SWEAT GLANDS
 Apocrine sweat glands contain chemicals
called pheromones, which are believed to
play a role in courtship and social behavior
ex.) dogs sniffing people
Why does your sweat smell so bad?
 The secretions are easily broken down by
bacteria, which creates body odors.
Chapter 4 – The Skin and Its Parts
SWEAT GLANDS
2. Eccrine Sweat Glands
 Found mostly on the skin of armpits,
forehead, palms, and soles
 Eccrine sweat gland activity is
genetically determined
 Human eccrine sweat is composed
primarily of water with various
concentrations of salts, organic
compounds, and wastes, including
urea.
Chapter 4 – The Skin and Its Parts
Interesting Fact:
Antiperspirants can be used to reduce the
amount of sweat (from both gland types),
thereby reducing odors and dampness.
How do antiperspirants work?
There is an electrical repulsion between a
negatively charged ingredient and the
negatively charged sweat molecules.
Chapter 4 – The Skin and Its Parts
NAILS
• Fingernails & toenails are nothing more than
a keratin secretion.
• Keratinocytes at the base of the nail root
gradually move up to the surface of the skin.
• The cells closest to the surface die, flatten,
press tightly together, & disintegrate to form
the nail body.
• Fingernails of a healthy person typically grow
1/8th an inch per month (slightly faster than
toenails)
Chapter 4 – The Skin and Its Parts
Wellness and Illness over
the Life Span
Aging is due to:
• Intrinsic factors
aging caused by the natural decline of cells
OR
• Extrinsic factors
aging caused by environmental factors
(disease, pollution, sun exposure)
One’s lifestyle can accelerate aging.
Chapter 4 – The Skin and Its Parts
Wellness and Illness over
the Life Span
Pathology can be categorized as:
• Degenerative
refers to diseases that progressively
deteriorate tissues
examples include skin cancer, moles,skin tags
• Genetic
includes acne, psoriasis, spider veins
• Infectious
diseases including impetigo, ringworm, warts
DISORDERS:
HOMEOSTATIC IMBALANCES
• Skin cancer can be caused by excessive
exposure to sunlight.
• Risk factors for skin cancer include skin
type, sun exposure, family history, age, and
immunological status.
Skin disorders
• Basal cell carcinoma
30% of Caucasians get this type of skin
cancer. Does not metastasize.
• Squamous Cell carcinoma arises from the
keratinocytes in the stratum spinosum. May
metastasize (spread to other body parts).
• Melanoma arises in the melanocytes. Rapidly
metastasizes.
Melanocytes
• Produces melanin
for protection from
UV radiation.
• Responsible for
skin color.
• Melanoma.
Melanoma
ABCD Rule
Asymmetry, Border irregularity, Color, Diameter
Burns
• Denaturation of cell proteins.
• Dehydration, protein loss, and infection.
• First degree burns only the epidermis (sunburn).
• Second degree burns epidermis and upper
dermis. May include fluid-filled blisters that
separate epidermis & dermis. Heals without
grafting in 3 to 4 weeks & may scar
• Third degree burns = full thickness burns
– destroy epidermis, dermis & epidermal
derivatives
– damaged area is numb (not painful at all) due
to loss of sensory nerves
-- Skin grafting is almost always necessary.
Types of Burns
Tattoos
• Tattooing is a
permanent coloration
of the skin in which a
foreign pigment is
injected into the
dermis.
Possible Dangers of
Body Tattoos
• Infection, allergic reaction to the ink,
psoriasis, and dermatitis
• Diseases such as HIV, AIDS, Hepatitis B
and C, and even syphilis
• Body tattoos can also cause tumors