Ch. 3 Skin Structure and Growth

Skin Structure and Growth

CHAPTER 3

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May not be scanned, copied, or duplicated, or posted to a publicly accessible website, in whole or in part.

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1.

Explain why cosmetologists must understand
skin structure and growth.

2.

List the skin’s three major layers, their sublayers,
and their functions.

3.

Describe the nerves in the skin and their
functions.

4.

Define melanin and how it affects skin pigment.

5.

Describe the role of collagen and elastin.

6.

List the two major glands of the skin and their
functions.

7.

List the skin’s six functions.

LEARNING OBJECTIVES

Why Study Skin Structure and Growth?

To advise your clients on how to improve their overall appearance:

• Knowing the skin structure is crucial to providing excellent skin care for clients.

• Understanding advances in technology, ingredients, and delivery systems will

ensure that you can offer state-of-the art advice to your clients on how to protect,
nourish, and preserve the health and beauty of their skin.

• Cosmetologists cannot diagnose, prescribe medications for, or provide any

treatment for abnormal skin conditions, illnesses, or diseases. Refer clients to a
dermatologist.

Dermatologist- Physician who specializes in diseases

and disorders of the skin, hair, and nails

Dermatology-Medical branch of science that deals with

the study of skin and its nature, structure, functions,

diseases, and treatment

Multiple Choice

All of the following are reasons cosmetologists should understand skin structure and growth EXCEPT:

• Providing excellent skin care for clients depends on knowing the skin's underlying structure and needs.

• Advising clients on protecting, nourishing, and preserving skin health and beauty relies on understanding advances in technology, ingredients, and delivery systems.

• Advising clients on how to improve their skin to be healthy-looking requires knowledge of skin structure and growth.

• Diagnosing and providing treatment for abnormal skin conditions, illnesses, or diseases requires knowledge of skin structure and growth.

Copyright © 2023 Milady, a part of Cengage Learning®

May not be scanned, copied, or duplicated, or posted to a publicly accessible website, in whole or in part.

Rally Robin

Working with your face partner.

Person A goes first - 20 seconds each

●What experiences have you had
with skin care services in the salon
or spa?

●Why did you receive skin care
services?

Skin Layers and
Their Functions

Healthy skin= free of any visible signs
of disease, infection, or injury.

Approximately 50 to 70 percent water
and is slightly moist, soft, and has a
smooth, fine-grained texture.

The surface of healthy skin is slightly
acidic.

Appendages of the skin include hair,
nails, and sudoriferous (sweat) and
sebaceous (oil) glands.

As the body’s largest organ, the skin is
composed of three main components:
the epidermis, the dermis, and the
subcutaneous layer.

Multiple Choice

Water is the number one nutrient of the body and composes what percentage of the body's skin?

• 10 to 30 percent

• 30 to 50 percent

• 50 to 70 percent

• 70 to 90 percent

Copyright © 2023 Milady, a part of Cengage Learning®

May not be scanned, copied, or duplicated, or posted to a publicly accessible website, in whole or in part.

Epidermis

Stratum Corneum

Stratum lucidum

Stratum granulosum

Stratum spinosum

Stratum germinativum

The epidermisis the outermost
and thinnest layer of the skin. It
contains no blood vessels, but it
does have many small nerve
endings. The epidermis is made up
of five layers called strata (singular:
stratum).

Copyright © 2023 Milady, a part of Cengage Learning®

May not be scanned, copied, or duplicated, or posted to a publicly accessible website, in whole or in part.

Stratum Corneum. Aka the horny layer. Epidermis’s outer layer and what we see when we look at the
skin. It has overlapping skin cells and forms a barrier to protect underlying tissues from infection, dehydration,
chemicals, and mechanical stress. The cells are continually being shed and replaced by cells rising to the surface
from the skin’s sublayers. The stratum corneum is made up of keratin, a fibrous protein that is also the principal
component of skin, hair, and nails. The stratum corneum’s cells combine with lipids (fats) produced by the skin
to help make it a protective, water-resistant layer. The complex of lipids between the cells is known as the
barrier function. It keeps the skin moist by preventing water evaporation, guarding against irritants penetrating
the skin surface, and helping regulate the skin’s pH. - Layer treated by cosmetologists -

Stratum lucidum. The clear, translucent layer under the stratum corneum; it consists of small cells through which
light can pass. This layer is located only on the palms of the hands, soles of the feet, and digits. It forms our
unique fingerprints and footprints.

Stratum granulosum. Also known as the granular layer, is the layer of the epidermis composed of cells that look
like granules and are filled with keratin. The cells die as they are pushed to the surface to replace dead cells
shed from the stratum corneum.

Stratum spinosum.Also known as the spiny layer, is just above the stratum germinativum. Where the process of
skin cell shedding begins. The largest layer of the epidermis.

Stratum germinativum. More commonly called the basal cell layer, is the epidermis’s deepest layer. This is the
living layer where everything starts. It is composed of several layers of differently shaped cells. The basal cell
layer also contains special cells called melanocytes, which produce skin pigment called melanin. Melanin
protects the sensitive cells in the dermis (located below the epidermis) from the destructive effects of excessive ultraviolet (UV) light from the sun and ultraviolet lamps.

Multiple Choice

Which layer of the epidermis forms unique fingerprints and footprints and is only located on the palms of the hands, the soles of the feet, and the digits

• stratum lucidum

• stratum corneum

• stratum spinosum

• stratum germinativum

The Dermis

Also known as derma, corium, cutis,
or true skin, is the skin’s underlying
or inner layer. The highly sensitive
dermis layer of connective tissue is
about 25 times thicker than the
epidermis.
Within its structure are numerous
blood vessels, lymph vessels,
nerves, sudoriferous (sweat) glands,
sebaceous (oil) glands, and hair
follicles, as well as arrector pili
muscles.

Multiple Choice

What is the underlying or inner layer of the skin?

• epidermis

• dermis

• papillary layer

• reticular layer

Papillary layer is the dermis’s outer layer, directly beneath the epidermis. Here you will find the dermal
papillae (singular: dermal papilla), which are membranes of ridges and grooves that attach to the
epidermis. Some papillae contain looped capillaries, and others contain small epidermal structures
called tactile corpuscles, with nerve endings that are sensitive to touch, pain, heat, cold, and pressure.
Note that papillae in the hair follicle are called hair papillae and are the small, cone-shaped structures at
the bottom of hair follicles.

Reticular layer is the deeper layer of the dermis that supplies the skin with oxygen and nutrients. It
contains the following structures within its network:

• Blood vessels

• Lymph vessels

• Sebaceous (oil) glands

• Sudoriferous (sweat) glands

• Hair follicles

• Arrector pili muscles

• Nerve endings

Two Layers of the Dermis

Subcutaneous Tissue

Subcutaneous layer AKA hypodermis or
superficial fascia, is composed of
subcutaneous tissue, AKA adipose tissue
or subcutis tissue. It’s the fatty tissue
below the dermis.

It gives the body smoothness and
contour, contains fats for energy, and
acts as a protective cushion for the skin.

It varies in thickness according to an
individual’s age, gender, and general
health.

Multiple Choice

What gives the body smoothness and contour while providing a protective cushion for the skin?

• arrector pili muscles

• dermal papillae

• subcutaneous tissue

• keratin

Nerves That Affect the Skin

•Motor nerve fibers: convey
impulses from the brain or spinal
cord to the muscles or glands.
Stimulate muscles, such as the
arrector pili muscles, attached to
the hair follicles.
•Secretory nerve fibers: motor nerves
attached to sweat and oil glands.
Regulate excretion from the sweat
glands and control sebum output to
the skin’s surface.

•Sensory nerve fibers:send
messages to the central nervous
system and brain to react to heat,
cold, touch, pressure, and pain.

Multiple Choice

Nerve fibers that send messages to the central nervous system and brain to react to heat, cold, touch, pressure, and pain are called _________.

• sensory nerve fibers

• secretory nerve fibers

• motor nerve fibers

• autonomic nerve fibers

Skin Pigments: Melanin

Melanin, the tiny grains of pigment (coloring
matter) produced by melanocytes and then deposited into cells in the stratum germinativum layer of the epidermis and the papillary layers of
the dermis.

Every person has the same number of
melanocytes, or pigment-producing cells.

• Some people’s cells produce more melanin than

others.

• The size, number, and makeup of the pigment

granules produce the depth and tone of an
individual’s skin, hair, and eye color.

• Both internal and external factors affect melanin

activation and production.

• Individuals with darker skin and melanin have more

activity in their melanocytes. This is an example of
an internal factor.

• An external factor influencing melanin production is

sun exposure.

Multiple Choice

Which sentence best defines melanin?

• This fibrous, connective tissue is made from protein that gives the skin form and strength.

• These tiny grains of pigment are produced by melanocytes in the stratum germinativum.

• This fatty or oily substance lubricates the skin and preserves hair's softness.

• This fibrous protein of cells is also principal component of skin, hair, and nails.

Two Types of Melanin

•Pheomelanin—red to yellow.

• Rosy skin, red or neutral hair tones

•Eumelanin—dark brown to black

• Cooler toned hair and skin tones

• Melanin production is stimulated by exposure to

sunlight and protects the cells below by absorbing
and blocking UV radiation.

• Melanin protects us from the sun but does not

provide enough protection to prevent skin
damage. Therefore, daily use of a
broad-spectrum sunscreen with a sun
protection factor (SPF) of 15 or higher can help
the melanin protect the skin from burning, skin
cancer, and premature aging.

• Broad spectrum means the sunscreen has been

shown to protect against UVA and UVB radiation
from the sun.

Multiple Choice

A broad-spectrum sunscreen is one that _________.

• supplements the skin with vitamin D and other actives

• protects the skin in a wide range of weather conditions

• provides protection for all skin tones

• has been shown to protect against UVA and UVB radiation from the sun

Strength and
Flexibility of the Skin

The skin gets its strength, form, and flexibility
from two specific structures (fibers) found within the dermis: collagen and elastin. They make up
70 percent of the dermis.

As we age, gravity causes these fibers to weaken,
and skin will produce less elastin than collagen,
resulting in sagging skin.

Using a daily broad-spectrum sunscreen with an SPF
of 15 or higher, maintaining a moisturizing skin care regimen, and keeping skin free of disease will slow
the weakening of collagen and elastin fibers and
help skin look younger longer.

Multiple Choice

Which is a reasonable prediction of an outcome for a client who does not use broad-spectrum sunscreen with a sun protection factor (SPF) of 15 or higher?

• Collagen and elastin fibers will weaken, and the client's skin will age prematurely.

• The skin's hydrolipidic film will break down and allow pathogens to penetrate the dry skin.

• Sebum on the epidermis will dry up, allowing for bacteria to penetrate the epidermis.

• The client will be susceptible to Sensory Processing Disorder, causing a lack of tolerance to hot and cold sensations on the skin.

Collagen.A fibrous connective tissue made from protein
that gives the skin form and strength.

• Makes up a large percentage of the dermis and

provides structural support by holding together
all the structures found in this layer.

• When collagen fibers are healthy, they allow the

skin to stretch and contract as needed.

• If collagen fibers become weakened due to age,

lack of moisture, environmental damage such as
UV light, or frequent weight changes, the skin
will begin to lose its tone and suppleness.

• Wrinkles and sagging are often the result of

collagen fibers losing their strength.

Elastin.A protein base similar to collagen that forms
elastic tissue.

• Elastin is interwoven with the collagen fibers and

gives the skin its flexibility and elasticity.

• It helps the skin regain its shape, even after

being repeatedly stretched by external factors
like tugging or pulling, or expanded by internal
factors such as weight gain or pregnancy.

• The same factors that weaken collagen also

weaken elastin.

Multiple Choice

What is the function of elastin?

• It determines the depth and tone of an individual's skin, hair, and eye color.

• It lubricates the skin and preserves hair's softness.

• It gives the skin flexibility and elasticity.

• It gives the skin form and strength.

Apocrine

sweat gland

Skin Glands

Eccrine

sweat gland

Sudoriferous Glands

Sudoriferous glands, also known as sweat
glands, excrete perspiration and detoxify the
body by excreting excess salt and unwanted
chemicals..

Sudoriferous glands regulate body temperature
and help eliminate waste products from the body.

• Evaporation of sweat cools the skin’s

surface.

• Sudoriferous glands’ activity is greatly

increased by heat, exercise, emotions,
and certain drugs.

• Normally, 1 to 2 pints (0.5 to 1 liter) of

fluids containing trace amounts of
minerals such as sodium, potassium,
and magnesium are eliminated daily
through sweat pores in the skin.

Multiple Choice

Which example illustrates the skin's heat regulation function?

• The barrier function prevents water evaporation.

• Melanocytes produce melanin.

• Sudoriferous glands excrete perspiration.

• Sebaceous glands secrete sebum.

Sebaceous (Oil) Glands

Sebaceous glands, also known as oil
glands, are connected to the hair
follicles.

They consist of little sacs with ducts
that open into the follicles.

These glands secrete sebum, a fatty or
oily substance that lubricates the skin
and preserves hair’s softness.

With the exceptions of the palms of the
hands and the soles of the feet, these
glands are found in all body parts,
particularly in the face and scalp, where
they are larger.

Sebaceous
(Oil) Glands

Multiple Choice

What is the function of sebaceous glands?

• to secrete oil to lubricate the skin

• to excrete sweat to regulate body temperature and eliminate waste products

• to produce the skin pigment melanin

• to keep the skin moist by preventing water evaporation

Skin Functions

●Protection: Sebum on the epidermis protects from
external factors, such as bacteria invasion. Acid mantle
is the protective barrier made up of sebum, lipids,
sweat, and water. These components form a
hydrolipidic film to protect the skin from drying out and
from exposure to external factors that could damage it.
Hydro means “water.” Lipidic means “oil.” A hydrolipidic
film provides an oil–water balance on the skin’s
surface. Acid mantle has an average pH of 5.5. Skin’s
pH protects the body from pathogens.

●Sensation: The skin responds to heat, cold, touch,
pressure, and pain. When the nerve endings are
stimulated, a message is sent to the brain.

●Heat regulation: A healthy body maintains an internal
temperature of about 98.6 degrees Fahrenheit (37
degrees Celsius). As environmental temperature
changes, the skin’s blood and sudoriferous glands
make necessary adjustments to help cool down the
body by the evaporation of sweat.

●Excretion: Perspiration from the sudoriferous
glands is excreted through the skin. Water lost
through perspiration takes salt and other
chemicals with it. Sudoriferous glands serve to
prevent the body from overheating.

●Secretion: Sebaceous glands secrete sebum.
This oil lubricates the skin, keeping it soft and
pliable. Oil also keeps hair soft. Emotional stress
and hormone imbalances can increase the flow
of sebum.

●Absorption: The skin’s outer layers can absorb
some ingredients, but very few ingredients can
penetrate the epidermis. Small amounts of fatty
materials, such as those used in many advanced
skin care formulations, may be absorbed
between the cells and through the hair follicles
and sebaceous gland openings. Cosmetic
products are not formulated to penetrate the
epidermis.

Multiple Choice

All of the following are skin functions EXCEPT ___________.

• absorption

• heat regulation

• sensation

• add necessary body weight to maintain good health

Rally Robin

Working with your shoulder partner.
Partner B goes first - 30 seconds total

List the 6 skin functions

• Using different types of candy and cereal, you are going to create a model of

the skin.

• The model must identify each of the layers as well as their functions. If the

functions can’t be listed on the model, include them on a paper.
Include all layers in the correct order and a list of the functions in
detail.

Page 64
Fig. 3-2

Subcutaneous layer: marshmallows
Dermis: peanut butter chips
Nerve fibers: twizzlers (pulled apart)
Epidermis:
Germinativum: chocolate chips
Spinosum: candy corn
Granulosum: golden crisp cereal
Lucidum: gummy bears
Corneum: frosted flakes
Hair shaft: pocky sticks