The integumentary system consists of the skin and its accessory structures. The skin has two main layers - the epidermis and dermis. The epidermis is made of stratified squamous epithelium and provides protection, while the dermis contains connective tissue, hair follicles, and glands. The skin regulates body temperature, protects the body, and produces vitamin D. Accessory structures include hair, sebaceous glands, and sweat glands that also have protective and regulatory functions. Injuries like burns damage the skin layers and heal in stages from the surface to deeper tissues.

1. ADEA. CERVANTES. LOMOTOS. LAROT. NALUAN. PACTOLERIN. GABRONINO | SECTION A8 1
[TRANS] LECTURE 3: THE INTEGUMENTARY SYSTEM
THE INTEGUMENTARY SYSTEM
● The integumentary system consists of the skin and
accessory structures, such as hair, glands, and nails.
o Integument means covering, and the integumentary
system is one of the more familiar systems of the
body to everyone because it covers the outsid of
the body and is easily observed.
● Also known as cutaneous membrane
o Covers the external surface of the body and is the
largest organ of the body in weight
● In adults, it covers an area about 2 square meters (22
square feet) and weighs 4.5–5 kg (10–11 lb), about 7% of
total body weight.
o It ranges in thickness from 0.5 mm (0.02 in.) on the
eyelids to 4.0 mm (0.16 in.) on the heels.
▪ Over most of the body it is 1–2 mm (0.04–0.08 in.)
thick.
MAJOR FUNCTIONS OF THE INTEGUMENTARY
SYSTEM
● Although we are often concerned with how the
integumentary system looks, it has many important
functions that go beyond appearance.
o Major functions of the integumentary system includes:
PROTECTION
Figure 1. The Integumentary System
● The skin provides protection against abrasion and
ultraviolet light. It also prevents microorganisms from
entering the body and reduces water loss, thus preventing
dehydration.
o The integumentary system performs many protective
functions:
1. The intact skin plays an important role in reducing water
loss because its lipids act as a barrier to the diffusion of
water.
2. The skin prevents microorganisms and other foreign
substances from entering the body. Secretions from skin
glands also produce an environment unsuitable for some
microorganisms.
3. The stratified squamous epithelium of the skin protects
underlying structures against abrasion.
4. Melanin absorbs ultraviolet light and protects underlying
structures from its damaging effects.
5. Hair provides protection in several ways: The hair on the
head acts as a heat insulator, eyebrows keep sweat out
of the eyes, eyelashes protect the eyes from foreign
objects, and hair in the nose and ears prevents the entry
of dust and other materials.
6. The nails protect the ends of the fingers and toes from
damage and can be used in defense.
SENSATION
● The integumentary system has sensory receptors that
can detect heat, cold, touch, pressure, and pain.
o Although hair does not have a nerve supply, sensory
receptors around the hair follicle can detect the
movement of a hair.
VITAMIN D PRODUCTION
● When exposed to ultraviolet light, the skin produces a
molecule that can be transformed into vitamin D, an
important regulator of calcium homeostasis.
OUTLINE
I The Integumentary
System
A Major functions of the
integumentary system
i Protection
ii Sensation
iii Vitamin D
production
iv Temperature
Regulation
vExcretion
II The Skin
A Epidermis
B Dermis
C Skin Color
D Subcutaneous Tissue
III Accesory Skin Structures
A Hair
B Glands
i Sebaceous Glands
ii Sweat Glands
C Nails
i Lunula
IV Integumentary system as
a Diagnostic aid
V Burns
A First-degree burns
B Second-degree burns
C Third-degree burns
VI Skin Cancer
A Three main types of
skin cancer
i Basal cell carcinoma
iiSquamous cell
carcinoma
iii Malignant
melanoma
VII Effects of Aging on the
Integumentary System
VIII Pressure Ulcer
IX References
Lecturer Book Supplementary Notes Internet PPT
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SUMMARY OF ABBREVIATIONS

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ADEA. CERVANTES. LOMOTOS. LAROT. NALUAN. PACTOLERIN. GABRONINO | SECTION A8 2
TEMPERATURE REGULATION
● The amount of blood flow beneath the skin’s surface and
the activity of sweat glands in the skin both help regulate
body temperature.
o Body temperature normally is maintained at about
37°C (98.6°F).
Figure 2. Temperature Regulation
EXCRETION
● Small amounts of waste products are lost through the skin
and in gland secretions.
o The integumentary system plays a minor role in
excretion, the removal of waste products from the
body.
▪ In addition to water and salts, sweat contains
small amounts of waste products, such as urea,
uric acid, and ammonia.
THE SKIN
● The skin is made up of two major tissue layers: the
epidermis and the dermis.
o The epidermis (ep-i-der′ mis; upon the dermis) is the
most superficial layer of skin.
▪ It is a layer of epithelial tissue that rests on the
dermis (der ′ mis), a layer of dense connective
tissue.
● The skin rests on the subcutaneous (sub-koota ′ ne-us;
under the skin) tissue, which is a layer of connective tissue.
EPIDERMIS
1. Stratum corneum - most superficial stratum of the
epidermis. It consists of dead squamous cells filled with
keratin.
2. Stratum lucidum - a thin somewhat translucent layer of
cells lying superficial to the stratum granulosum and
under the stratum corneum especially in thickened parts
of the epidermis (as of the palms or the soles of the feet).
3. Stratum granulosum - is a thin layer of cells in the
epidermis lying above the stratum spinosum and below
the stratum corneum
4. Stratum spinosum - 8-10 cell layers, also known as the
prickle cell layer contains irregular, polyhedral cells with
cytoplasmic processes, sometimes called “spines”, that
extend outward and contact neighboring cells by
desmosomes.
5. Stratum basale/germinativum - is the deepest layer,
separated from the dermis by the basement membrane
(basal lamina) and attached to the basement membrane
by hemidesmosomes.
● The epidermis is stratified squamous epithelium; in its
deepest layers, new cells are produced by mitosis.
● During their movement, the cells change shape and
chemical composition.
o This process is called keratinization (ker′ a-tin-i-za′
shun) because the cells become filled with the protein
keratin (ker′ a-tin), which makes them hard.
Figure 3. Skin and Subcutaneous Tissue
● The skin, consisting of the epidermis and the dermis, is
connected by the subcutaneous tissue to underlying
structures.
o Note the accessory structures (hairs, glands, and
arrector pili), some of which project into the
subcutaneous tissue, and the large amount of
adipose tissue in the subcutaneous tissue.
DERMIS
● The dermis is composed of dense collagenous connective
tissue containing fibroblasts, adipocytes, and
macrophages.
o Nerves, hair follicles, smooth muscles, glands, and
lymphatic vessels extend into the dermis.

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ADEA. CERVANTES. LOMOTOS. LAROT. NALUAN. PACTOLERIN. GABRONINO | SECTION A8 3
Figure 4. Epidermis and Dermis
● Papillary region - The papillary layer is the top layer of
your dermis.
o It's much thinner than the reticular dermis.
● Reticular region - The reticular layer is the bottom layer
of your dermis.
o It's thick, and it contains blood vessels, glands, hair
follicles, lymphatics, nerves and fat cells.
● The upper part of the dermis has projections called
dermal papillae, which extend toward the epidermis
o The dermal papillae - contain many blood vessels that
supply the overlying epidermis with nutrients, remove
waste products, and help regulate body temperature.
SKIN COLOR
● Factors that determine skin color include pigments in the
skin, blood circulating through the skin, and the thickness
of the stratum corneum.
● Melanin (mel ′ a-nin; black) is the group of pigments
primarily responsible for skin, hair, and eye color.
o Most melanin molecules are brown to black pigments,
but some are yellowish or reddish.
▪ Melanin provides protection against ultraviolet
light from the sun.
Figure 5. Melanin Transfer to Epithelial Cells
● Carotene (kar ′ o -te n) - is a yellow pigment found in
plants such as squash and carrots.
SUBCUTANEOUS TISSUE
● The subcutaneous (under the skin) tissue - , which is not
part of the skin, is sometimes called hypodermis (hı̄ -po -
der′ mis; under the dermis).
● Adipose tissue - in the subcutaneous tissue functions as
padding and insulation, and it is responsible for some of
the differences in appearance between men and women
as well as between individuals of the same sex.
ACCESORY SKIN STRUCTURES
● The accessory skin structures are hair, glands, and nails.
HAIR
● In humans, hair is found everywhere on the skin, except
on the palms, the soles, the lips, the nipples, parts of the
genitalia, and the distal segments of the fingers and toes.
● Hair follicle - an extension of the epidermis that originates
deep in the dermis
● A hair has a hard cortex, which surrounds a softer center,
the medulla (me-dool′ a).
● The cortex is covered by the cuticle (ku ′ ti-kl; skin), a
single layer of overlapping cells that holds the hair in the
hair follicle
● Associated with each hair follicle are smooth muscle cells
called the arrector (which raises) pili (hair)
o Contraction of the arrector pili causes the hair to
become more perpendicular to the skin’s surface, or
to “stand on end,” and it produces a raised area of
skin called a “goose bump.”
GLANDS
● The major glands of the skin are the sebaceous glands
and the sweat glands
SEBACEOUS GLANDS
● Sebaceous glands are simple, branched acinar glands.
o Most are connected by a duct to the superficial part of
a hair follicle.
▪ They produce sebum, an oily, white substance
rich in lipids.
SWEAT GLANDS

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ADEA. CERVANTES. LOMOTOS. LAROT. NALUAN. PACTOLERIN. GABRONINO | SECTION A8 4
● There are two kinds of sweat glands: eccrine and
apocrine.
o Eccrine (ek ′ rin) sweat glands are simple, coiled,
tubular glands and release sweat by merocrine
secretion.
▪ Eccrine glands are located in almost every part of
the skin but most numerous in the palms and
soles.
o Apocrine (ap′ o -krin) sweat glands are simple, coiled,
tubular glands that produce a thick secretion rich in
organic substances.
Figure 6. Hair Follicle
NAILS
● The nail is a thin plate, consisting of layers of dead
stratum corneum cells that contain a very hard type of
keratin.
o The visible part of the nail is the nail body, and the
part of the nail covered by skin is the nail root.
● The cuticle, or eponychium (ep-o -nik′ e -u m), is stratum
corneum that extends onto the nail body.
o The nail root extends distally from the nail matrix.
● The nail also attaches to the underlying nail bed, which is
located distal to the nail matrix.
● A small part of the nail matrix, the lunula (loo ′ noo-la;
moon), can be seen through the nail body as a whitish,
crescentshaped area at the base of the nail
Figure 7. Glands of the Skin
Figure 8. Nail
Figure 9. Accessory Structures

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ADEA. CERVANTES. LOMOTOS. LAROT. NALUAN. PACTOLERIN. GABRONINO | SECTION A8 5
● Average nail growth: 1 mm (0.04 in.) per week, slower in
toenails.
o Functions:
▪ Protection
▪ Support and counterpressure to the palmar
surface of the fingers
▪ Grasp and object manipulation
INTEGUMENTARY SYSTEM AS A DIAGNOSTIC AID
● The integumentary system is useful in diagnosis
because it is observed easily and often reflects events
occurring in other parts of the body.
● A yellowish skin color, called jaundice (jawn ′ dis), can
occur when the liver is damaged by a disease, such as
viral hepatitis.
BURNS
● A burn is injury to a tissue caused by heat, cold, friction,
chemicals, electricity, or radiation.
FIRST-DEGREE BURNS
● First-degree burns involve only the epidermis and are
red and painful.
o Slight edema (e-de′ ma), or swelling, may be present.
▪ They can be caused by sunburn or brief
exposure to very hot or very cold objects, and
they heal without scarring in about a week.
SECOND-DEGREE BURNS
● Second-degree burns damage both the epidermis and
the dermis. If dermal damage is minimal, symptoms
include redness, pain, edema, and blisters.
o Healing takes about 2 weeks, and no scarring results.
● In all second-degree burns, the epidermis regenerates
from epithelial tissue in hair follicles and sweat glands, as
well as from the edges of the wound.
THIRD-DEGREE BURNS
● In full-thickness burns, or third-degree burns, the
epidermis and the dermis are completely destroyed, and
recovery occurs from the edges of the burn wound.
Figure 10. Stages of Burns
Feature Thin Skin Thick Skin
Distribution All parts of body
except areas such as
palms, palmar surface
of digits, and soles.
Areas such as palms,
palmar surface of
digits, and soles.
Epidermal
thickness
0.10–0.15 mm (0.004–
0.006 in.).
0.6–4.5 mm (0.024–
0.18 in.), due mostly to
a thicker stratum
corneum.
Epidermal
strata
Stratum lucidum
essentially lacking;
thinner
strata spinosum and
corneum.
Stratum lucidum
present; thicker strata
spinosum and
corneum.
Epidermal
ridges
Lacking due to poorly
developed, fewer,
and less-well-
organized dermal
papillae.
Present due to well-
developed and more
numerous dermal
papillae organized in
parallel rows.
Table 1. Types of Skin
● Epidermal Wound Healing - Slight damage to the
superficial epidermal cells; includes abrasions and minor
burns.
● Deep Wound Healing - The injury extends to the dermis
and subcutaneous layer. Requires complex healing
processes and the healed tissue loses some of its normal
function due to scar tissue formation.
o Divided into four phases:
▪ Inflammatory phase – Blood clot forms in the
wound and loosely unites the wound edges.
Inflammation happens, blood vessels dilate, and
immune response is mediated to eliminate
microbes, foreign material, and dead tissue.
▪ Migratory phase – The clot becomes a scab.
Fibroblasts migrate along fibrin threads and begin
synthesizing scar tissue. Damaged blood vessels
begin to regrow.
▪ Proliferative phase – Characterized by extensive
growth of epithelial cells, deposition by fibroblasts
of collagen fibers in random patterns (type III),
continued growth of blood vessels.
▪ Maturation phase – The scab sloughs off and the
epidermis returns to normal thickness. Collagen
fibers become more organized (type I),
fibroblasts decrease in number, and blood
vessels return to normal.
● Fibrosis - Scar tissue formation
o Scar tissue differs from normal skin in that its collagen
fibers are more densely arranged, has decreased
elasticity, fewer blood vessels, and may or may not
contain the same number of accessory structures.
▪ Hypertrophic scar – A raised scar within the
boundaries of the original wound.
Feature Thin Skin Thick Skin
Hair follicles
and arrector
pili muscles
Present Absent
Sebaceous
glands
Present Absent
Sudoriferous
glands
Fewer More numerous
Sensory
receptors
Sparser Densor

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ADEA. CERVANTES. LOMOTOS. LAROT. NALUAN. PACTOLERIN. GABRONINO | SECTION A8 6
▪ Keloid/cheloid scar – A raised scar that extends
beyond the boundaries of the original wound.
Figure 11. Fibrosis
Figure 12. Stages of Burns
SKIN CANCER
● Skin cancer is the most common type of cancer. Although
chemicals and radiation (x-rays) are known to induce
cancer, the development of skin cancer most often is
associated with exposure to ultraviolet (UV) light from the
sun.
THREE MAIN TYPES OF SKIN CANCER
BASAL CELL CARCINOMA
● Basal cell carcinoma (kar-si-no ′ ma ), the most frequent
type, begins with cells in the stratum basale and extends
into the dermis to produce an open ulcer.
Figure 13. Basal Cell carcinoma
SQUAMOUS CELL CARCINOMA
● Squamous cell carcinoma develops from cells
immediately superficial to the stratum basale.
Figure 14. Squamous cell carcinoma
MALIGNANT MELANOMA
● Malignant melanoma (mel′ a -no ′ ma ) is a rare form of
skin cancer that arises from melanocytes, usually in a
preexisting mole.
o A mole is an aggregation, or “nest,” of melanocytes.
Figure 15. Malignant Melanoma
EFFECTS OF AGING ON THE INTEGUMENTARY
SYSTEM
● Blood flow to the skin is reduced, the skin becomes
thinner, and elasticity is lost.
● Sweat and sebaceous glands are less active, and the
number of melanocytes decreases
PRESSURE ULCERS
● Pressure ulcers form as a result of constant or prolonged
pressure exerted on the skin.
o Typically occur in people with conditions that
decrease their mobility, making postural change
difficult.
● Decubitus ulcer formation is multifactorial (external and
internal factors), but all these results in a common
pathway leading to ischemia and necrosis.
Figure 16. Pressure Ulcers

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ADEA. CERVANTES. LOMOTOS. LAROT. NALUAN. PACTOLERIN. GABRONINO | SECTION A8 7
● Rule-of-nines method for determining the extent of a
burn. The percentages are the approximate proportions of
the body surface area.
Figure 17. Rule of Nines
● The rule of nines is a quick way for estimating the surface
area affected by a burn in an adult
REFERENCES
Notes from the discussion by: Carl Howell Ponce
Bontuyan
Southwestern University powerpoint presentation:
Integumentary System
Seeley’s Essential of Anatomy and Physiology, 9th
Edition
Tortura’s Principles of Anatomy and Physiology, 14th
Edition