Download Chapter 4 Integumentary System

Chapter 4
Integumentary System
Human Anatomy and Physiology
Integumentary System

Composed of
– skin
– Sweat glands
– Oil glands
– Hairs
– Nails
Functions

Protection against
– Damage
– Ultraviolet radiation
– Desiccation (drying out)

Aids in temperature regulation
 Aids in excretion of urea and uric acid
 Synthesizes Vitamin D
Structure of Skin

Skin composed of two kinds of tissue that are firmly
connected to each other
– Epidermis
– Dermis

If these two layers separate, a blister forms.
 Deep to dermis is the subcutaneous tissue (hypodermis) –
not actually considered a layer of skin
– Made of adipose tissue
– Anchors the skin to underlying organs
Structure of Skin
Epidermis



Made of stratified
squamous epithelium that
can keratinize (become
hard and tough)
Avascular – no blood
supply of its own
Composed of five layers
called strata
–
–
–
–
–
Stratum basale
Stratum spinosum
Stratum granulosum
Stratum lucidum
Stratum corneum
Layers of Epidermis

Stratum basale
– Deepest cell layer
– Only epidermal cells that receive
adequate nourishment via
diffusion of nutrients from the
dermis
– Constantly undergoing cell
division
Layers of Epidermis

Cells move up to the
next layer, Stratum
Spinosum
 Then, Stratum
Granulosum where
they start to become
flatter, increasingly
full of keratin and
finally the cells die
Layers of Epidermis

Stratum Lucidum
– present where the skin
is hairless and extra
thick, palms of hands
and soles of feet
Layers of Epidermis

Stratum Corneum
– Outermost layer
– 20-30 cell layers thick, ¾ of the epidermal thickness
– Composed of dead cell remnants, completely filled with
keratin

Keratin waterproofs skin
– Totally new epidermis every 25 to 45 days
Melanin

Pigment that ranges in
color from yellow to
brown to black
 Produced by
melanocytes found in
the stratum basale
 When skin exposed to
sunlight, melanocytes
produce more melanin
and tanning occurs
Melanin

forms a protective umbrella over the cells’
nuclei which shields DNA from the
damaging effects of the UV radiation
 Freckles and moles are seen where melanin
is concentrated in one spot
Dermis

Made of dense
connective tissue
 Two major
regions:
– Papillary layer
– Reticular layer
Dermis – Papillary Layer
– Upper layer
– Contain dermal
papillae
 Uneven
fingerlike
projections
which indent the
epidermis
Dermis – Papillary Layer
Furnish nutrients to
the epidermis
 Provide
fingerprints
 Contain pain
receptors:
Meissner’s
corpuscles

Dermis

Reticular layer
– Deepest skin
layer
Dermis – Reticular Layer
– Contains
blood vessels, hair
follicles, sweat
and oil glands
 Rich nerve supply
 deep pressure
receptors: Pacinian
corpuscles

Dermis – Reticular Layer

Contains:
–Collagen: responsible for toughness
and attracts and binds water to help
hydrate the skin
–Elastic fibers: give skin elasticity
• Decreases with age causing wrinkles
Dermis and Body
Temperature

Blood vessels
 Sweat secretion
Skin Color

Three pigments:
1. Melanin
 amount and kind – yellow, black, or brown
2. Carotene
 Orange-yellow pigment found in carrots and other
orange, deep yellow or leafy green vegetables
3. Amount of oxygen bound to hemoglobin
 Hemoglobin is the pigment in blood cells – gives
the crimson color – rosy glow
Appendages of the Skin

Exocrine Glands
– release secretions to
the skin surface via
ducts
– Two groups:
 Oil glands
(sebaceous glands)
 Sweat glands

Hair and Hair Follicles
 Nails
Sebaceous Glands

Oil glands
 Found all over skin
except palms and soles
 Produces sebum
– Lubricant that keeps
skin soft and moist
– Contains chemicals
that kill bacteria
Sebaceous Gland Problems

Whitehead: blocked by sebum
 Blackhead: If sebum dries it darkens
 Acne: active infection
 Increased secretion during adolescence
cause skin problems
Sweat Glands

More than 2.5 million per person
 Two types:
– Eccrine glands
– Apocrine glands
Eccrine Sweat Glands

More numerous
 Found all over body
 Produce sweat that
pours through pores
 Regulate body heat
Sweat

Sweat is a clear secretion that is made of
– water
– salts
– vitamin C
– traces of metabolic wastes like ammonia, urea, uric acid,
and lactic acid (lactic acid attracts mosquitos)

Acidic (pH 4 to 6 )
– Inhibits growth of bacteria
Apocrine sweat glands

Located mostly in axillary and genital areas
 Ducts empty into hair follicles
 Breakdown of secretion by skin bacteria
produces musky odor.
Hairs

Millions all over body
 Serve protective function
 Hairs lost most of usefulness because we
have other means of keeping warm unlike the
early humans.
Hair Anatomy

Produced by hair
follicle
 Flexible epithelial
surface
 Root: part of hair
enclosed in the follicle
 Shaft: part of hair
projecting from the
surface
Why do my hairs stand on end?

Arrector pili
– Muscles that connect
each side of the hair
follicle to the dermal
tissue
– When these muscles
contract, the hair is
pulled upright, causing
“goose bumps”
Nails

Visible part is
called nail body
 Root is hidden by
cuticle
 Nail bed changes
color with blood
flow change
Tissue Repair

Tissue injury stimulates inflammatory
response.
 Wound healing (tissue repair) occurs two
ways
– Regeneration
– Fibrosis
Regeneration

Replacement of destroyed tissue by the
same kind of cells
Fibrosis

Repair by dense connective tissue by the
formation of scar tissue
Overview of Steps for Tissue
Repair
1.
2.
3.
4.
blood escapes from dermal blood
vessels, and blood clot soon forms
blood clot and dried tissue fluid form a
scab protecting the area blood vessels
send out
branches and fibroblasts migrate into
the area
fibroblasts produce new connective
fibers, scab sloughs off
Steps of tissue healing

Capillaries allow fluid rich in clotting
proteins and other substances to seep into
injured area from the bloodstream.
 Leaked clotting proteins construct a clot,
which stops loss of blood, holds wound
together. This prevents bacteria from
spreading to surrounding tissues.
 Clot exposed to air, dries and hardens,
forming scab
Steps of Tissue Healing

Granulation tissue forms
– Delicate pink tissue composed largely of
capillaries that grow into damaged area from
undamaged blood vessels.
– Contain phagocytes that dispose of blood clot
and fibroblast (connective tissue cells) that
make collagen fibers (scar tissue) to
permanently bridge the gap.
Steps of Tissue Healing

Surface epithelium begins to regenerate and
makes its way across the granulation tissue
just beneath the scab, which then detaches.
 Final result : fully regenerated surface
epithelium that covers the scar.
 Scar can be visible or invisible.
Keloid Scars

result of an overly
aggressive healing
process
 extend beyond the
original injury
 may affect mobility
 Possible treatments
include surgical
removal, or
injections with
steroids
Contracture scars

If your skin has been
burned, you may have a
contracture scar, which
causes tightening of skin
that can impair your
ability to move;
additionally, this type of
scar may go deeper to
affect muscles and
nerves.
Hypertrophic scars

Raised and red scars that
are similar to keloids, but
do not breach the
boundaries of the injury
site.
 Possible treatments can
include injections of
steroids to reduce
inflammation.
Acne Scars

If you've had severe
acne, you probably
have the scars to prove
it.
FYI……

Epithelial Tissue regenerate easily.
 Connective tissue including bone regenerate
easily as well.
 Skeletal Muscle regenerates poorly, if at all.
 Cardiac Muscle and Nervous tissue are
replaced only by scar tissue.
Imbalances of the Skin

Infections and Allergies
–
–
–
–
–
–

Athlete’s Foot
Boils and Carbuncles
Cold Sores
Contact dermatistis
Impetigo
Psoriasis
Burns
– 1st degree
– 2nd degree
– 3rd degree

Skin Cancer
– Basal cell carinoma
– Squamous cell carcinoma
– Malignant melanoma
 ABCD RULE

Other Disorders
– Erythema
– Pallor
– Jaundice
– Decubitus ulcer
– bruises
Infections and Allergies

Athlete’s Foot:
– itchy fungal infection of the toes
Infections and Allergies

Boils and Carbuncles:
– inflammation of hair
follicles and sebaceous
glands
Infections and Allergies

Cold Sores:
– fever blisters; small
fluid filled blisters that
itch an sting, caused by
herpes simples
infection
Infections and Allergies

Contact dermatitis:
– itching, redness, and
swelling of the skin,
progressing to blistering
– Caused by exposure of the
skin to chemicals like poison
ivy that provoke allergic
responses
Infections and Allergies

Impetigo
– Pink, water-filled raised
lesions that develop a
yellow crust and eventually
rupture
– Causes by a highly
contagious staphylococcus
infection
Infections and Allergies

Psoriasis
– Chronic condition characterized by
reddened epidermal lesions covered
with dry, silvery scales
Burns


Tissue damage and cell death caused by intense
heat, electricity, UV radiation (sunburn), or
certain chemicals (acids)
When the skin is burned, two life threatening
problem result:
1. Dehydration
2. Infection
1st threat: Dehydration


The body loses fluids containing proteins
and electrolytes
This can lead to a shutdown of the kidneys
and circulatory shock
2nd threat: Infection

Leading cause of death
 Burned skin is sterile for about 24 hours,
but after that pathogens easily invade and
multiply rapidly
Rule of Nines

Divides the body area into 11 areas, each accounting
for 9 percent of the total body surface, plus 1%
surrounding the genitals
BURNS
Burns

1st degree
– Only the epidermis is
damaged
– Becomes red and
swollen
– Not usually serious and
generally heal in two to
three days without any
special attention
– sunburn
Burns

2nd degree
– Involve injury to the
epidermis and the upper
region of the dermis
– Skin is red and painful
and blisters appear
– Re-growth of the
epithelium can occur
– No permanent scars result
if care is taken to prevent
infection

3rd degree
– Destroy the entire
–
–
–
–
thickness of the skin
Appears gray-white or
blackened
Nerve endings are
destroyed so the burn is
not painful
Regeneration is not
possible
Skin grafting must be
done to cover the
underlying exposed
tissues
Burns
Burns

Considered critical if any of the following
conditions exists:
– 1. Over 25 % of the body has 2nd degree burns
– 2. Over 10% of the body has 3rd degree burns
– 3. Any third-degree burn of the face, hands, or
feet
Skin Cancer

Most skin tumors are benign and do not
spread
 Some are malignant (cancerous) and tend to
invade other parts of the body
 Skin cancer is the most common type of
cancer in the body
Basal Cell Carcinoma

Least malignant and most
common
 Full cure rate in 99% of
patients
Squamous Cell Carcinoma

Believed to be suninduced
 If it is caught early and
removed surgically,
good chance of complete
cure
Malignant Melanoma

Cancer of the melanocytes
 Accounts for 5% of skin cancers
 Often deadly – 50% survival rate
 Usually appears as a spreading
brown to black patch that
metastasizes rapidly to
surrounding lymph and blood
vessels
ABCD Rule

Asymmetry: the two sides of the pigmented spot
of mole do not match
 Border Irregularity: The borders of the lesion are
not smooth but exhibit indentations
 Color: the pigmented spot contains areas of
different colors
 Diameter: the spot is larger than 6 mm in
diameter (size of pencil eraser)

An abnormal
yellow skin tone
usually indicates a
liver disorder in
which excess bile
pigments are
absorbed into the
blood, circulated
throughout the
body, and deposited
in body tissues.
Jaundice
Decubitus ulcer

Restriction of blood
supply to the skin
results in cell death,
and if severe or
prolonged, ulcers.
 Occur in bedridden
patients who are
not turned regularly
Bruises

Reveal sites where blood has escaped from
the circulation and has clotted in the tissue
spaces
 Hematoma: clotted blood mass
 An unusual tendency to bruising may
signify a deficiency of vitamin C in the diet
or hemophilia