Transcript Notes: Skin
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