Chapter 5 - Integumentary System

Integumentary
System for
Medical Students
INTEGUMENTARY SYSTEM
Integument means covering. It consists of the skin
and accessory structures, such as hair, glands, and
nails.
Why is it important to study integumentary system?
 It can indicate physiological imbalances in the body.
 providing useful signs for diagnosis (Other disorders affect
different parts of the body but are reflected in the
integumentary system)
 For example, reduced blood flow through the skin during a
heart attack can cause a person to look pale, whereas
increased blood flow as a result of fever can cause a
flushed appearance.
 Also, some diseases cause skin rashes, such as those
characteristic of measles, chicken pox, and allergic
reactions.
5. Major Functions
INTEGUMENTARY
SYSTEM
Function of the integumentary system
01 02 03 04 05
Vit. D Temperature
Protects Sensation Excretion
Production regulation
5.2. SKIN
The skin is made up of two major
tissue layers: the epidermis and
the dermis..
Layers of the skin
Epidermis
Most Superficial
layer of the skin
Dermis Hypodermis
Responsible for Subcutaneous
skin structural tissue – connects
strength skin to muscles/
bones
Epidermis
The epidermis is stratified squamous epithelium divided into strata.
∙ New cells are produced in the stratum basale.
∙ The stratum corneum consists of many layers of dead squamous
cells containing keratin. The most superficial layers are sloughed.
Keratinization is the transformation of stratum basale cells into

stratum corneum cells.
∙ Structural strength results from keratin inside the cells and from
desmosomes, which hold the cells together.
∙ Lipids surrounding the stratum corneum cells help prevent fluid
loss.
Dermis
1. The dermis is dense connective tissue.
2. Collagen and elastic fibers provide structural
strength, and the blood vessels of the papillae supply
the epidermis with nutrients
● 3. more collagen fibers are
oriented in some directions than
in others. This produces cleavage
lines, or tension lines
Epidermis and Dermis
● The upper part of the dermis has projections
called DERMAL PAPILLAE which extend
toward the epidermis. Recall that the
epidermis lacks blood vessels; however, the
dermal papillae contain many blood vessels.
Blood flow through these vessels supplies
the overlying epidermis with nutrients,
removes waste products, and helps regulate
body temperature
● An injection delivers substances, such as medicines, to the body
by puncturing the skin. An intradermal injection is administered
by drawing the skin taut and inserting a small needle at a
shallow angle into the dermis; an example is the tuberculin skin
test. A subcutaneous injection is achieved by pinching the skin
to form a “tent” and inserting a short needle into the adipose
tissue of the subcutaneous tissue; an example is an insulin
injection. An intramuscular injection is accomplished by
inserting a long needle at a 90-degree angle to the skin into a
muscle deep to the subcutaneous tissue. Intramuscular
injections are used for most vaccines and certain antibiotics.
Skin Color
● Melanocytes produce melanin, which is responsible for
different skin colors. Melanin production is determined
genetically but can be modified by exposure to ultraviolet
light and by hormones.
● Carotene, a plant pigment ingested as a source of vitamin A,
can cause the skin to appear yellowish.
● Increased blood flow produces a red skin color, whereas
decreased blood flow causes a pale skin color. Decreased
blood O2 results in the blue skin color of cyanosis.
● Scattering of light by collagen produces a bluish color.
Melanin production is determined by genetic factors, exposure to light, and
hormones. Genetic factors are responsible for the amounts of melanin produced in
different races. Since all races have about the same number of melanocytes, racial
variations in skin color are determined by the amount, kind, and distribution of
melanin. Although many genes are responsible for skin color, a single mutation can
prevent the production of melanin. For example, albinism (al′bi-nizm) is a
recessive genetic trait that causes a deficiency or an absence of melanin. Albinos
have fair skin, white hair, and unpigmented irises
in the eyes. Exposure to ultraviolet light—
for example, in sunlight— stimulates melanocytes
to increase melanin production. The result is
a suntan.
5.3 Subcutaneous Tissue
Subcutaneous tissue
1. The subcutaneous tissue, which is not part of the skin, is loose
connective tissue that attaches the skin to underlying tissues.
2. About half of the body’s lipids are stored in the subcutaneous
tissue.
3. Loose connective tissue including adipose tissue that contains
about half the body’s stored lipids.
4. Adipose tissue functions as padding & insulation & responsible
for some of the differences in appearance between
men & women
5.4
Accessory Skin
Structures
HAIR
 Hairs are columns of dead, keratinized
epithelial cells. Each hair consists of a shaft
(above the skin), a root (below the skin), and
a hair bulb (site of hair cell formation).
 Hairs have a growth phase and a resting
phase.
 Contraction of the arrector pili, which are
smooth muscles, causes hair to “stand on
end” and produces a “goose bump”.
Parts of
Hair
Glands
*Sebaceous glands produce
sebum, which oils the hair
and the surface of the skin.
*Eccrine sweat glands
produce sweat, which cools
the body.
*Apocrine sweat glands
produce an organic secretion
that causes body odor when
broken down by bacteria.
Nail
*The nail consists of thesnail body and the nail root.
*The nail matrix produces the nail, which is composed
of stratum corneum cells containing hard keratin
5.5 Physiology of the Integumentary System
1. Protection
- The skin reduces water loss, prevents the entry of
microorganisms, and provides protection against abrasion
and ultraviolet light; hair and nails also perform protective
functions.
2. Sensation
- The skin contains sensory receptors for pain, heat, cold, and
pressure.
3. Vitamin D Production
- Ultraviolet light stimulates the production of a precursor molecule in
the skin that is modified by the liver and kidneys into vitamin D.
- Vitamin D increases calcium uptake in the small intestine.
4. Temperature Regulation
- Through dilation and constriction of blood vessels, the skin controls
heat loss from the body.
- Evaporation of sweat cools the body.
5. Excretion
- Skin glands remove small amounts of waste products but are not
important in excretion.
5.6 Integumentary System as a
Diagnostic Aid
The integumentary system is easily observed and
often reflects events occurring in other parts of the
body (e.g., cyanosis, jaundice, rashes)
Burns
1. Partial-thickness burns damage only the
epidermis (first-degree burn) or the epidermis and
the dermis (second-degree burn).
2. Full-thickness burns (third-degree burns) destroy
the epidermis, the dermis, and usually underlying
tissues
5.8 Skin Cancer
1. Basal cell carcinoma involves the cells of the
stratum basale and is readily treatable.
2. Squamous cell carcinoma involves the cells
immediately superficial to the stratum basale and
can metastasize.
3. Malignant melanoma involves melanocytes, can
metastasize, and is often fatal
5.9 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
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Integumentary

Keratinization is the transformation of stratum basale cells into

 Blood flow to the skin is reduced, the skin becomes thinner,

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