Skin and the
Integumentary System
Chapter 6
Aids for understanding
 Cut- skin
 Derm- skin
 Epi- upon
 Follic- small bag
 Kerat- horn
 Melan- black
 Seb- grease
Clinical
 Transdermal patch contains drug
 Diffuses into the epidermis and enters
the blood vessels of the dermis
Skin
 Organ vital in maintaining homeostasis
 Protective covering
 helps regulate body temp.
 retards water loss
 houses sensory receptors
 synthesizes biochemicals
 excretes small quantities of waste
Epidermis
 Lacks blood vessels
 Stratum basale close
to the dermis is
nourished by dermal
blood vessels
 Farther cells move,
poorer nutrient supply,
cells die
 Older cells harden in a
process called
keratinization forming
stratum corneum
 In healthy skin,
production=loss
 Rate of cell division
increases where the
skin is rubbed or
pressed regularly
(calluses, corns)
 Melanocytes produce
melanin
 Absorbs UV radiation,
preventing mutations in
DNA of the skin
Skin Color
 All have same # of
melanocytes
 Amt. produced
determines darkness
 Environmental factors
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Sunlight
Sunlamps
X-rays
 Physiological factors
 Amt. of blood
 Diet
 Biochemical imbalance
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 Explain how the epidermis is formed.
 Distinguish between the stratum basale and
the stratum corneum.
 What is the function of melanin?
 What factors influence skin color?
Dermis
 Boundary is uneven
 Dermal papillae extend between
epidermal ridges and form fingerprints
 Dermis binds epidermis to underlying
tissues
 Blood vessels supply nutrients to all skin
cells
 Nerve cell processes are scattered
throughout
 Contains hair follicles, sebaceous
glands, and sweat glands
Clinical
 Interference with blood
flow may kill epidermal
cells
 Pressure ulcer may
appear
 Occur in the skin
overlying bony
projections
 Frequently changing
body position or
massaging the skin to
stimulate blood flow can
prevent ulcers
Subcutaneous Layer (hypodermis)
 Consists of loose connective and adipose
tissues
 Insulates
 Contains major blood vessels
Accessory Organs of the Skin
 Nails
Protective coverings on the ends of the
fingers and toes
 Consists of a nail plate that overlies a
surface of skin called the nail bed
 The whitish, half-moon shaped lunula at
the base covers the most actively
growing region
 FYI: thumb nail grows slowest; the
middle nail grows fastest!

Hair Follicles
 Present on all surfaces except palms, soles,
lips, nipples, and parts of the reproductive
organs
 Each hair develops from a follicle
 Contains hair root
 Composed of dead epidermal cells
 Arrector pili muscle attaches to each hair
follicle
Clinical
 Just above base of
follicle are stem cells
that can give rise to hair
and other epidermal
cells
 Manipulating these cells
could someday treat
baldness or extreme
hairiness
Nerve Receptors
 Pacinian corpuscle
 Detects vibrations and heavy touch sensations and
sends impulses to the brain
 Meissner’s corpuscle
 Detects light touch sensations and sends impulses to
the brain
Sebaceous glands
 Holocrine glands that secrete an oily
mixture of fatty material and cellular debris
called sebum through ducts into the hair
follicles
Clinical
 Acne vulgaris – disorder
of the sebaceous
glands
 Overactive and
inflamed glands
become plugged and
surrounded by small,
red elevations
containing blackheads
or pimples
Sweat Glands
 glands consist of a tiny tube that originates as
a ball-shaped coil in the deeper dermis
 Eccrine glands respond to body temp.



Common on forehead, neck, and back
Sweat carried away in a duct that opens to the
outside (pore)
Sweat is mostly water, but contains salt and
waste
 Apocrine glands secrete sweat when a person is
upset, frightened, or in pain
 Ceruminous glands of the external ear canal secrete
earwax
 Mammary glands secret milk
Clinical
 The avg. sq. in. of skin holds 650 sweat
glands, 20 blood vessels, 60,000
melanocytes, and more than a thousand
nerve endings.
Journey Through The Skin
 Write a narrative essay of
your journey through the
skin.
 Pretend as though I know
nothing about these
structures.
 Be sure to “visit”
 Hypodermis



Adipose tissue
Blood vessels
Dermis



Nerves
Hair
Dermal papillae
Arrector pilius
 sebaceous gland
 Sweat gland
 Pores
 Epidermis
 Stratum corneum
 Stratum basale
 melanocytes

Regulation of Body Temperature
 Even slight shifts can disrupt metabolic rates
 37°C (98.6°F)
 How it works:

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Body temp. rises
warmed blood reaches the brain
signal sent to muscles in the walls of dermal
blood vessels to relax
heat escapes
Signal sent to sweat glands to release sweat
Clinical
 Hypothermia – core body
temp. falls below 95°F
 Gradual loss of
coordination
 Stiffening muscles
 Confusion
 Fatigue
 Slow, shallow breathing
 At 87.8°F, the skin turns
bluish-gray, weakness
intensifies, and
consciousness ebbs
away
 Hyperthermia – core
body temp. exceeds
106°F




Skin becomes hot, dry,
and flushed
Person becomes
weak, dizzy, and
nauseous
Headache
Rapid, irregular pulse
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 Why is regulation of body temp. so
important?
 How does the body lose excess
heat?
 Which actions help the body
conserve heat?
Healing of Wounds
 Inflammation – normal response to injury or
stress; red and painfully swollen
 blood vessels dilate and become more
permeable forcing fluids to the leave the blood
vessels and enter damaged tissue
 Injuries


Shallow break in skin – epithelial cells divide
more rapidly
Deep – blood vessels break, escaping blood
forms clot (blood clot + dried tissue fluid = scab),
fibroblasts form new fibers



Phagocytic cells remove dead cells and other
debris
Scab sloughs off
Scar may form
 Large open wounds

Healing accompanied by granulation (new
branch of a blood vessel and a cluster of
collagen-secreting fibroblasts)
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 Describe how inflammation helps a wound
heal.
 Distinguish between the activities necessary
to heal a wound in the epidermis and those
necessary to heal a wound in the dermis.
 Explain the role of phagocytic cells in wound
healing.
 Define granulation.
Skin Cancer
 the abnormal growth of skin cells — most
often develops on skin exposed to the sun
 There are three major types of skin cancer


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basal cell carcinoma
squamous cell carcinoma
melanoma
basal cell carcinoma
 most common form of nonmelanoma skin
cancer
 rarely fatal, but can cause extensive damage
to surrounding tissue and bone if they're not
removed
 have a high recurrence rate
 Most basal cell carcinomas are caused by
long-term exposure to ultraviolet (UV)
radiation from sunlight
squamous cell carcinoma
 second most common form of nonmelanoma
skin cancer following basal cell carcinoma
 rarely causes further problems when caught
and treated early
 Untreated, squamous cell carcinoma can
grow large or spread to other parts of your
body, causing serious complications.
melanoma
 the most serious type of skin cancer,
develops in the cells that produce melanin
 can also form in your eyes and, rarely, in
internal organs, such as your intestines
 The exact cause of all melanomas isn't clear,
but exposure to ultraviolet (UV) radiation
increases your risk; your genetic makeup
may also play a role
How to identify?
 http://www.mayoclinic.com/health/melanoma/
DS00575&slide=2