Download Integumentary System Marieb Altered

PowerPoint® Lecture Slides
prepared by Vince Austin,
Bluegrass Technical
and Community College
CHAPTER
Elaine N. Marieb
Katja Hoehn
Human
Anatomy
& Physiology
SEVENTH EDITION
Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings
5
The
Integumentary
System
Components of the Integumentary System

Skin

Hair

Nails

Glands
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Skin (Integument)

A large organ composed of all 4 tissue types

22 square feet

1-2mm thick

~10lbs.

Consists of three major regions


Epidermis – outermost superficial region – only epithelial
tissue
Dermis – middle region – has connective, nervous and
muscular tissue
Hypodermis (superficial fascia or Subcutaneous Layer) –
deepest region – Adipose and Areolar Tissue
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
Hair shaft
Pore
Dermal papillae
(papillary layer
of dermis)
Epidermis
Meissner's corpuscle
Free nerve ending
Reticular layer of dermis
Sebaceous (oil) gland
Arrector pili muscle
Dermis
Sensory nerve fiber
Eccrine sweat gland
Pacinian corpuscle
Artery
Hypodermis
(superficial
fascia)
Hair root
Hair follicle
Eccrine sweat
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gland
Vein
Adipose tissue
Hair follicle receptor
(root hair plexus)
Figure 5.1
Epidermis

Composed of keratinized stratified squamous
epithelium, consisting of four distinct cell types
and four or five layers

Cell types include keratinocytes, melanocytes,
Merkel cells, and Langerhans’ cells

Outer portion of the skin is exposed to the external
environment and functions in protection

Stratified Squamous Epithelium

Avascular

5 Distinct Layers
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Cells of the Epidermis

Keratinocytes – 90%,
Make keratin



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Melanocytes – 8% -produce
the brown pigment melanin
Langerhans’ cells –
epidermal macrophages that
help activate the immune
system
Merkel cells – function as
touch receptors in
association with sensory
nerve endings
Layers of the Epidermis
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Figure 5.2b
Layers of the Epidermis: Stratum Basale
(Basal Layer)

Deepest epidermal layer firmly attached to the
dermis

Consists of a single row of the youngest
keratinocytes – Stratum Germinativum

Contains Keratinocytes, Merkel Cells,
Melanocytes and Stem Cells
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Layers of the Epidermis: Stratum Spinosum
(Prickly Layer)

8-10 Layers of cells

Cells contain a weblike system of intermediate
filaments attached to desmosomes

Melanin granules and Langerhans’ cells are
abundant in this layer
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Layers of the Epidermis: Stratum Granulosum
(Granular Layer)

Thin; three to five cell layers of flat dying cells

Show nuclear degeneration
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Layers of the Epidermis: Stratum Lucidum
(Clear Layer)

Thin, transparent band superficial to the stratum
granulosum

Consists of a 3-5 rows of flat, dead keratinocytes

Present only in thick skin
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Layers of the Epidermis: Stratum Corneum
(Horny Layer)

Outermost layer of keratinized cells (25-30
layers) – surrounded by lipids


Continuously shed
Accounts for three quarters of the epidermal
thickness
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Keratinization and Epidermal Growth


~4 week journey for keratinocytes from the bottom
to the top of the skin
Psoriasis – chronic skin disorder

Cells shed in 7-10 days as flaky silvery scales

Abnormal keratin produced
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Skin Grafts


If stratum basale layer and its stem cells are
destroyed, new skin CANNOT regenerate
Skin Graft – covering of a wound with a piece of
healthy skin

Autograft – from self

Isograft – from twin

Autologous Skin – transplant of a patient’s skin
that was grown in a culture
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Layers of the Epidermis
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Figure 5.2b
Dermis

Second major skin region containing strong,
flexible connective tissue



Collagen and elastic fibers, fibroblasts,
macrophages and adipocytes
Composed of two layers – papillary and reticular
Contains hair follicles, glands, nerves and blood
vessels
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Layers of the Dermis: Papillary Layer

Papillary layer

Areolar connective tissue with collagen and elastic
fibers

Its superior surface contains peglike projections
called dermal papillae

Dermal papillae contain capillary loops, Meissner’s
corpuscles, and free nerve endings
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Layers of the Dermis: Reticular Layer

Reticular layer

Accounts for approximately 80% of the thickness
of the skin

Collagen fibers in this layer add strength and
resiliency to the skin

Elastin fibers provide stretch-recoil properties
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Hypodermis

Subcutaneous layer deep to the skin

Composed of adipose and areolar connective tissue
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Skin Color

Three pigments contribute to skin color

Melanin – yellow to reddish-brown to black pigment,
responsible for dark skin colors






Freckles and pigmented moles – result from local
accumulations of melanin
Made by melanocytes
Same number of melanocytes in everyone
UV rays in sunlight increase melanin
Albinism – in alack of tyrosinase, so the body can’t covert
tyrosine into melanin = no pigment
Vitiligo – autoimmune loss of melanocytes in areas of the
skin which produces white patches
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Skin Color


Carotene – yellow to orange pigment, most
obvious in the palms and soles of the feet
 Found in Stratum Corneum and Dermis
Hemoglobin – reddish pigment responsible for the
pinkish hue of the skin
 Carries oxygen in the blood
 If other pigments are not present, the epidermis
is translucent so pinkness will be evident
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Skin Color as a Diagnostic Clue



Jaundice

Yellowish color to skin and whites of eyes

Build-up of yellow bilirubin in the blood from the liver not
breaking it down properly
Cyanotic

Bluish color to nail beds and skin

Hemoglobin is depleted of oxygen – looks purple/blue
Erythema

Redness of skin due to the enlargement of capillaries in the
dermis

Present during inflammation, infection, allergy or burns
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Glands of the Skin

Specialized Exocrine Glands found in the Dermis

Sebaceous (Oil) Glands

Sudiferous or Sudoriferous (Sweat) Glands


Mammary Glands (Milk)
Ceruminous (Wax) Glands
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Sebaceous Glands





Simple alveolar glands found all over the body
Soften skin when stimulated by hormones
Secrete an oily secretion called sebum
Most open into hair shafts
Sebum…



Keeps hair and skin soft and pliable
Inhibits growth of bacteria and fungi
Acne


Bacterial inflammation of glands
Secretions stimulated by hormones at puberty
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Sweat Glands

Secrete products through ducts

Regulate body temperature through perspiration



Eccrine sweat glands – found in palms, soles of
the feet, and forehead
Apocrine sweat glands – found in axillary and
pubic areas – secretory portion in dermis with duct
that opens onto hair follicle
Mammary glands – specialized sweat glands that
secrete milk
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Ceruminous Glands

Modified sweat glands that produce a waxy
secretion in the ear canal

Cerumen contains secretions of oil and wax
glands


Helps form a barrier to the inner ear – prevents
foreign bodies from getting in
Impacted cerumen may impact hearing
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Hair

Strands of dead keratinized cells produced by hair
follicles

Contains hard keratin which is tougher and more
durable than soft keratin of the skin

Made up of the shaft projecting from the skin, and
the root embedded in the skin

Consists of a core called the medulla, a cortex, and
an outermost cuticle

Pigmented by melanocytes at the base of the hair
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Hair Function and Distribution

Functions of hair include:

Helping to maintain warmth

Alerting the body to presence of insects on skin

Guarding the scalp against physical trauma, heat
loss, and sunlight

Eyelashes protect eyes
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Hair Function and Distribution

Hair is distributed over the entire skin surface
except:

Palms, soles, and lips

Nipples and portions of the external genitalia
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Hair Structures

Arrector Pili


Hair Root Plexus

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Smooth muscle in
dermis that
contracts with cold
or fear
Detects hair
movement
Types of Hair


Vellus – pale, fine body hair found in children and
the adult female
Terminal – coarse, long hair of eyebrows, scalp,
axillary, and pubic regions
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Hair Thinning and Baldness

Alopecia – hair thinning in both sexes

True, or frank, baldness


Genetically determined and sex-influenced
condition
Male pattern baldness – caused by follicular
response to DHT
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Hair Color

Result of melanin in the hair bulb – made by
melanocytes

Dark hair contains true melanin

Blond hair contains melanin and sulfur

Red hair contains melanin and iron

Gray hair is a result of a decline in melanin
production

White hair is a result of air bubbles in the hair shaft
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Structure of a Nail

Scalelike modification of the epidermis on the distal,
dorsal surface of fingers and toes

Tightly packet keratinized cells.

3 parts

Nail Body (visible portion, pink b/c of capillaries, free
edge is white)

Nail Root (buried under skin layers, lanula is white due
to a thick Stratum Basale


Eponychium (cuticle) – stratum corneum layer
Nails grow about 1mm per week
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Figure 5.6
Nail Picture
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Functions of the Integumentary System


Protection – chemical, physical, and mechanical
barrier
Body temperature regulation is accomplished by:





Dilation (cooling) and constriction (warming) of
dermal vessels
Increasing sweat gland secretions to cool the body
Cutaneous sensation – exoreceptors sense touch
and pain
Excretion and Absorption
Synthesis of Vitamin D
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Synthesis of Vitamin D

Sunlight activates a precursor to Vitamin D

Enzymes in the liver and kidneys transform that
molecule into Calcitrol – most active form of
Vitamin D

Calcitrol is necessary in the absorption of Ca from
food in the gastrointestinal tract.
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Types of Skin

Thin Skin




Covers most of the body
Thin epidermis – no Stratum Lucidum
No epidermal ridges, less sweat glands and sensory
receptors
Thick Skin



Only on palms and soles
Thick epidermis – distinct Stratum Lucidum and
thick Stratum Corneum
Lacks hair follicles and sebaceous glands
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Photodamage

UVA and UVB rays both damage the skin

Acute overexposure causes sunburn

DNA damage in epidermal cells can lead to skin
cancer

UVA produces oxygen free radicals that damage
collagen and elastic fibers and lead to wrinkling of
the skin
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Skin Cancer

Most skin tumors are benign and do not
metastasize

A crucial risk factor for nonmelanoma skin cancers
is the disabling of the p53 gene

Newly developed skin lotions can fix damaged
DNA

~1 million cases diagnosed per year
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Skin Cancer

The three major types of skin cancer are:

Basal cell carcinoma – rarely metastisize

Squamous cell carcinoma – may metastisize

Malignant melanomas – metastisize quickly
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Basal Cell Carcinoma

Least malignant and most common skin cancer

Stratum basale cells proliferate and invade the
dermis and hypodermis

Slow growing and do not often metastasize

Can be cured by surgical excision in 99% of the
cases
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Squamous Cell Carcinoma

Arises from keratinocytes of stratum spinosum

Arise most often on scalp, ears, and lower lip

Grows rapidly and metastasizes if not removed

Prognosis is good if treated by radiation therapy or
removed surgically
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Melanoma

Cancer of melanocytes is the most dangerous type
of skin cancer because it is:

Highly metastatic

Resistant to chemotherapy
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Skin Cancers
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Figure 5.7a–c
Melanoma

Melanomas have the following characteristics
(ABCD rule)

A: Asymmetry; the two sides of the pigmented
area do not match

B: Border is irregular and exhibits indentations

C: Color (pigmented area) is black, brown, tan,
and sometimes red or blue

D: Diameter is larger than 6 mm (size of a pencil
eraser)
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Melanoma

Treated by wide surgical excision accompanied by
immunotherapy

Chance of survival is poor if the lesion is over 4
mm thick

Resistant to Chemotherapy

Risk factors – skin color, sun exposure, family
history, age and immunological status
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Burns

Destruction of proteins of the skin


Chemicals, electricity, heat
Problems



Shock due to water, plasma and plasma protein
loss
Circulatory and kidney problems from loss of
plasma
Bacterial Infection
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Types of Burns - 3
First-degree
 Second Degree
 Third Degree

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1st Degree Burns

Only effect the epidermis

Simple sunburn
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Burns

Second-degree – destroys the entire epidermis
and part of the dermis
 Fluid-filled blisters separate the epidermis
and dermis
 Epidermal derivatives are not damaged
 Heals without grafting in 3-4 weeks, may
cause scarring
 Symptoms mimic first degree burns, but
blisters also appear
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Burns

Third-degree – entire thickness of the skin is
damaged
 Epidermis, Dermis and Epidermal
Derivatives are damaged
 Burned area appears gray-white, cherry red, or
black; there is no initial edema or pain (since
nerve endings are destroyed)
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Rule of Nines

Estimates the severity of burns

Burns considered critical if:

Over 25% of the body has second-degree burns

Over 10% of the body has third-degree burns

There are third-degree burns on face, hands, or feet
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Rule of Nines
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Figure 5.8a
Developmental Aspects of the Integument:
Fetal

Epidermis develops from ectoderm

Dermis and hypodermis develop from mesoderm


Lanugo – downy coat of delicate hairs covering the
fetus
Vernix caseosa – substance produced by sebaceous
glands that protects the skin of the fetus in the
amnion
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Developmental Aspects of the Integument:
Adolescent to Adult

Skin and hair become oilier and acne may appear

Skin shows the effects of cumulative
environmental assaults around age 30

Scaling and dermatitis become more common
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Developmental Aspects of the Integument:
Old Age
 Epidermal replacement of cells slows and skin
becomes thinner

Skin becomes dry and itchy

Subcutaneous fat layer diminishes, leading to
intolerance of cold

Decreased elasticity and loss of subcutaneous
tissue leads to wrinkles

Decreased numbers of melanocytes and
Langerhans’ cells increase the risk of skin cancer
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