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Chapter 6
Skin and Its
Appendages
Structure of the
Skin
Structure
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Picture page 163 ( 197)
Integumentary system = skin
Skin is a thin relatively flat organ
Classified as a membrane: cutaneous
membrane
• Cutaneous Membrane is divided into
epidermis and dermis
Epidermis
• Outer, thinner epithelial layer.
• Develops from ectodermal germ layer,
usually by the 17th week of gestation the
baby’s has all the essential characteristics
of the adult’s
• Avascular
Dermis
• Inner, thicker connective layer
• Derived from the mesoderm
• Vascular
Dermal-epidermal junction
• Specialized area where cells of epidermis
meet connective tissue of dermis
• characteristics of the adult structure by the
9th week of gestation
Subcutaneous Layer
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Also called hypodermis
Lies beneath the dermis
Rich in fat and aerolar tissue
Irregular connective tissue
Epidermis
Dermis
Subcutaneous
layer
(hypodermis)
Epidermis
Page 200 in home books
Cell Types
• Epidermis is composed of several types of
epithelial cells
• Keratinocytes
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Most important cell in the epidermis
Comprise over 90% of epidermal cells
Filled with tough, fibrous protein called keratin
principle structural element of outer skin
Cell Types
• Melanocytes
– Contribute color to skin
– Protect from UV light
– Can be completely absent from skin in some
non-lethal conditions
Cell Types
Cell Types
• Langerhans Cells
– Dendritic cells (immune cells)
– Play a role in immune reactions that effect the
skin
– Cells originate in the bone marrow but migrate
to deep cell layers of the epidermis early in
life
Cell Layers of
Epidermis
Strata
Page 200 in home books
Stratum basale
• Base layer
• Single layer of columnar cells
• Only cells in this deepest layer of
epithelium undergoes mitosis
• Cells migrate from this layer to other
layers until they reach the surface and are
shed off
Stratum Spinosum
• Also called spiny layer
• Stratum germinativum is used to describe the
stratum basale and Stratum Spinosum together
• Formed from 8-10 layers of irregularly shaped
cells with very prominent intercellular bridge or
desmosomes
• Desmosomes appear to pull points of the plasma
membranes of adjoining cells toward one
another. Gives spiny appearance
• Cells are rich in RNA making them well equipped
to start protein synthesis needed for the
production of keratin
Stratum Granulosum
• Granular layer
• Process of surface keratin formation begins
• Sheet 2-4 layer deep filled with intensely staining
granules called keratohylin (required for surface keratin
formation)
• Cells start to degenerate
• High levels of lysosomal enzymes are present in
cytoplasm and nuclei are in the process of breaking
down
• In thin skin this layer may not be visible
Stratum Lucidum
• Clear layer
• Keratinocytes are very flat, closely packed
and clear
• Nuclei are usually absent
• Dying cells are filled with eleidin which is
eventually transformed to keratin
• Absent in thin skin
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Stratum Corneum
Horny layer
Most superficial layer of epidermis
Composed of thin squamous cells
At surface cells are dead and continuously being
shed
• Desmosomes holding together Keratinocytes
strengthen this layer
• Keratinization: process in which cells from
deeper layers migrate, fill with keratin and move
to surface
Stratum Corneum
• Sometimes called barrier area of skin
• Protects from water loss and environmental threats
• Glycophospholipids cement keratin into water proof
barrier.
• Glycophospholipids can be washed away by excessive
soaking. The keratin can then absorb water appearing
puffy and wrinkled
• Diseases can cause layer to thicken
• Hyperkeratosis: Thick, dry, scaly skin that is inelastic and
subject to painful fissures
Cell Layers
Thin and Thick
Skin
Thin and Thick Skin
• There are up to 5 layers of stratum or cell
layers. (stratum corneum, lucidum,
granulosum, spinosum, basale)
• Epidermal tissue can be categorized thin
or thick skin
• Most of the body surface is covered by
thin skin
• Hairless skin covering palms, fingertips,
soles of feet or other areas associated
with friction has a covering of thick skin
Thick skin
• Each of 5 strata of epidermis are
present and each stratum are
generally several layers thick
• Hair not found in thick skin
• Thick skin underlying dermal
papillae are raised in curving parallel
friction ridges forming fingerprints
or footprints
• Ridges allow us to pick up and
manipulate small items and supplies
slip resistance to the feet.
Thin skin
• Number of cell layers in the epidermal
stratum are less than in thick
• One or more strata may be entirely absent
• Friction ridges are not present
Epidermal
Growth and
Repair
Epidermal Growth and Repair
• Turnover or regeneration time describes period
required for a cell population to mature and
reproduce
• To maintain constant thickness, new cells must
be formed at the same rate that old keratinized
cells flake off from stratum corneum.
• Current research suggest regeneration time is
about 35 days
• Abrasion can accelerate skin regeneration time.
The result is an intense stimulation of mitotic
activity in the stratum basale and shortened
turnover period
• Continued abrasion can result in an abnormally
thick stratum corneum, producing calluses at
the point of abrasion.
Epidermal Growth and Repair
• Callus formation is normal but there are several
skin diseases by abnormally high mitotic activity
in the epidermis resulting in scales and lesions
• 10%-12% of cells in the stratum basale enter
mitosis each day
• Cells migrating to surface proceed upward in
vertical columns from groups of 8-10 of these
basal cells undergoing mitosis
• Each group of active basal cells, with its vertical
column of migrating keratinocytes is called
epidermal proliferating unit (EPU)
Review
• Identify two main layers of skin
• Terms thick and thin refer to which primary
layer of skin
• How do thin and thick skin differ
• Identify two main cell types found in the
epidermis
• List 5 layers of epidermis (strata)
Dermis
Page 200 in home books
Dermal-Epidermal Junction
• Specialized area where cells of epidermis meet
connective tissue of dermis
• characteristics of the adult structure by the 9th
week of gestation
• lies between papillary layer and the stratum
basale
• Combines basement membrane and includes
specialized fibrous elements and a
polysaccharide gel
• cement the superficial epidermis to the dermis
(glue the two layers together)
• Provides mechanical support for epidermis
Dermis
• Also called the corium or “true skin”
• Vascular
• Composed of thin papillary layer and
thicker reticular layer
• Much thicker than the epidermis
• Serves a protection function against
mechanical injury
Dermis
• Specialized network of nerves and nerve
endings called somatic sensory receptors
process sensory information
• At various levels the dermis may contain
muscle fibers, hair follicles, sweat and
sebaceous glands and many blood
vessels
• It is rich vascularity that plays an important
role in temperature regulation (discussed later)
Papillary Layer
• Thin superficial layer of the dermis
• Forms bumps called dermal papillae on its
surface
• Dermal-Epidermal Junction lies between
papillary layer and the stratum basale
• Composed of loose connective tissue elements
along with thin collagenous and elastic fibers
• Has characteristic ridges on surface due to
conforming tightly to dermal papillae
• Fingerprints and footprints allow us to grip so we
can grasp small objects and walk upright on
slippery surfaces (Friction Ridges)
Reticular Layer
• Thicker layer of dermis
• More of the dense reticulum or network of
fibers (most are collagenous) than in
papillary layer
• Dense collagenous fibers in this layer is
what produces leather in processed
animal skins (these fibers also give skin
toughness)
• Elastic fibers make skin stretchable
Reticular Layer
• Serves as a point of
attachment for skeletal and
smooth muscle fibers
• Most of the structures such as
muscle fibers, hair follicles,
sweat and sebaceous glands
are located in reticular layer
• Several skeletal muscle are
located in the skin of the face
and scalp and permit various
facial expressions
Reticular Layer
• Distribution of smooth muscle is much
more extensive than skeletal
• Each hair follicle has a small bundle of
involuntary muscle attached to it.
Called arrector pili muscle
• Contraction of these muscles makes
hair stand on end and raises skin
around hair
• Goosebump
• Have millions of somatic sensory
receptors
Dermal Growth and Repair
• Unlike epidermis, dermis does not
continually shed and regenerate
• Rapid regeneration of connective tissue in
dermis occur only unusual circumstances
such as wound healing
• Fibroblasts quickly reproduce and begin
forming a dense mass of new connective
tissue that will either be replaced by
normal tissue or become a scar
Dermal Growth and Repair
• Dense white bundles of collagenous fibers orient
themselves in patterns called cleavage lines or
Langer’s Lines. Page 167 (203)
• Surgical incisions are made parallel to cleavage
lines the resulting wound has less tendency of
gaping open and will tend to heal with a less
noticeable scar
• When elastic fibers are stretched too much
(pregnancy) Fibers weaken and tear and initially
resulting in pinkish or slightly bluish depressed
furrows with jagged edges
• When they heal and lose color they remaining
furrows appear as glistening silver-white scar
lines (stretch marks)
Hypodermis
Hypodermis
• Called subcutaneous layer, subQ or
superficial fascia
• Not part of the skin but usually discussed
with the skin
• Forms connection between skin and
underlying structures of the body
• Made up mostly of loose fibrous tissue and
adipose tissue
• Carries major vessels and nerves to skin
above
Review
• What is the name of the layer separating
the dermis from the epidermis?
• Which layer of the dermis forms the
bumps that produce the ridges on palms
and soles?
• Which layer is vascular? Dermis or
epidermis
• What is the main function of the
hypodermis?
Skin Color
Melanin
• Main determinant of skin color is the
quantity of melanin deposited in the
epidermis cells
• Melanin (pigment) is produced by
melanocytes
• Melanocytes scattered throughout the
stratum basale is roughly the same
amount for everyone
• It is the amount and type of melanin
pigment that melanocytes produce that
account for skin color variations
Melanin
• Two groups of melanin
– Eumelanin
– Pheomelanin
• Eumelanin
– “true Black”
– Very dark brown, sometimes
nearly black
– Dark skinned and dark haired
produce large quantities
– Absorbs more UV radiation
than pheomelanin
Melanin
• Pheomelanin
– “dusky black”
– Hints at lighter reddish and orange colors
– Very light skinned with reddish orange
freckles and red hair produce large quantities
and very little of eumelanin
Melanin
• Only melanocytes have ability to routinely
convert the amino acid tyrosine into
melanin pigments
• These pigment granules release tiny
melanosomes
• Melanosomes form a cap over the nucleus
in keratinocytes protecting it from UV
damage
• The enzyme tyrosinase regulate the
pigment producing process
Melanin
• 4-6 pairs of genes exert primary control of
the amount of melanin formed by
melanocytes
• Albinism can result if the enzyme
tyrosinase is absent from birth
• Heredity determines how dark or light
one’s skin color will be
• Prolonged UV exposure in light skinned
people causes melanocytes to increase
melanin production
Melanin
• Prolonged UV exposure in light skinned
people causes melanocytes to increase
melanin production
• Increasing age may influence melanocyte
activity
• Melanin production can be stimulated by
excess secretion of adrenocorticotropic
hormone (ACTH)
Other Pigment or Color Changing
Factors
• Beta-carotene: yellow pigment
– Can be converted by body into vitamin A
(important nutrient for skin growth)
– High consumptions of carrot juice or sweet
potatoes can cause yellowing of the skin
(especially in infants)
– Jaundice caused by bile pigments
Other Pigment or Color Changing
Factors
• Blood Flow
– Hemoglobin (reddish pigment)
– Increased flow causes skin to temporally be
redder
– Blood vessels dilate during blushing
– When blood vessels constrict the skin
becomes paler
Other Pigment or Color Changing
Factors
• Hemoglobin
– Low in O2 and high in CO2 can appear bluish
or cyanotic
– Hemoglobin changes from bright red to deep
maroon-red as it loses oxygen
– Light reflects from maroon-red and is diffused
by skin fibers may appear blue
– The darker the skin the greater amount of
unoxygenated skin must be present before
cyanosis (condition of blueness)
Other Pigment or Color Changing
Factors
• Bruising
– Damage to blood vessels permits release of
RBC
– These RBC produce the bluish colors
discussed earlier
– As blood clots it may appear darker blue or
even black
– Macrophages break down hgb into iron
containing hemosiderin (brownish pigment)
and several iron free bile pigments (yellow
and green)
Functions of the
Skin
Function of the Skin
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Protection
Sensation
Permits movement and growth
Endocrine (Vitamin D production)
Excretion
Immunity
Temperature regulation
• Page 171(207) for skin functions chart
Protection
• Barrier for underlying tissue against
microorganisms, chemicals and
mechanical injury
• Protects from dehydration of body fluids
and entry of excessive fluids from external
environment
• The pigment melanin protects us from
overexposure to UV light
Surface Film
• Mechanical barrier
• Produced by mixing residue from sweat
and sebaceous glands with cast off
epithelial cells (shedding of epithelial cells
is called desquamation)
• Has antibacterial and antifungal properties
• Lubricates and hydrates skin surface
• Buffers caustic irritants and blocks toxic
agents
Surface Film
• Chemical composition include:
– Amino acids, sterols and complex
phospholipids
– Fatty acids, triglycerides, and waxes
– Water, ammonia, lactic acid, urea and uric
acid
• Chemical composition varies from area to
area
Sensation
Flexibility
• Skin must be elastic and supple to allow
movement of the body without injury
• It grows as we grow
Vitamin D Production
Exposure to UV light
Taken to liver and
kidney by blood
Active form of vitamin D
Too much melanin in skin can keep bodies from synthesizing vitamin D
Excretion
• Plays minor role in the excretion of body
waste
• Excretes urea, uric acid and ammonia
(sweat)
Immunity
• Specialized cells attach to and attack
microorganisms in the skin
• Langerhan’s cells function with helper T
cells to trigger helpful immune reaction to
certain diseases.
Temperature Regulation
• Humans usually maintain a constant core
body temperature (aprox 37°C)
• Certain chemical reactions must take
place at specific temperatures
• Body must balance amount of heat it
produces with the amount of heat it loses
• Skin plays an important role in this
balance
Body Temperature
Regulation
Heat Production
• Heat is produced by
– metabolism of food
• Muscle and glands are the most active,
they metabolize more and produce more
heat
• During exercise and shivering heat
production is increased
• During sleep metabolism and heat
production slow
Heat Loss
• 80% of heat transfer occurs through the
skin
• Heat loss can be regulated by altering the
flow of blood in the skin
• If heat must be conserved blood vessels
constrict keeping warm blood flow deeper
in the body
• If heat lost must be increased vessels
dilate to increase flow to out tissue where
it is released into enviroment
Evaporation
• Heat energy must be expanded to
evaporate fluid
• Important in high environmental
temperatures
• Humid atmosphere retards evaporation
and lessens the cooling effect
Radiation
• Transfer of heat from the surface of one
object to another without actual contact
• Heat radiates to nearby objects that are
cooler
• Radiation accounts for a greater
percentage of heat loss than conduction
and evaporation do
Conduction
• Transfer of heat to any substance in actual
contact with body (jewelry, clothing, food,
etc)
• Accounts for relatively small amount of
heat loss
Convection
• Transfer of body heat by movement of
heated air
Homeostatic Regulation of Heat Loss
• Heat loss in skin is controlled by negative
feedback loop Page 174 (211)
• Hypothalamus has receptors that detect
body temperature changes
• Hypothalamus acts as integrator sending
signal to sweat glands and blood vessels
(effectors)
• they respond to promote heat loss
http://www.youtube.com/watch?v=H2CEhWLFfUc
Review
• What is the one means of heat production
in the body?
• In what organs do most heat production
occur?
• Name three processes heat is lost from
the body and explain
Appendages of
the Skin
Appendages of Skin
• Hair
• Nails
• Glands
Hair
• Tubular pockets called hair follicles develop in
parts of the skin many months before birth
• By 6th month fetus is covered with fine, soft hair
called lanugo, which is uasually lost before birth
• When lanugo hair is lost it is replaced by vellus
hair (stronger, fine less pigmented)
• Course pubic and axillary hair that develops at
puberty is called terminal hair
• In adult male terminal hair replaces 80-90% of
the vellus hair on chest, extremities and beard
Hair Growth
• Cells of epidermis spread down into
dermis to form small tube or follicle
• Follicle consists of two primary layers
– Outer dermal root sheath
– Epithelial root sheath
• Stratum germinativum develops into
follicle’s innermost layer and at bottom of
follicle forms a cap-shaped cluster of cells
known as germinal matrix
Hair Growth
• Protruding into germinal matrix is small
mound of dermis called hair papilla
• Hair papilla contained blood capillaries
that nourish germinal matrix
• Cells of germinal matrix are responsible
for forming hairs
• These cells undergo repeated mitosis,
push upward in follicle and become
keratinized to form hair
• As long as germinal matrix remains alive,
hair will regenerate
Hair Growth
• The root lies hidden in the
follicle
• The visible part of the hair is
called the shaft.
• Inner core is known as the
medulla
• Superficial portion around is
called the cortex
• Covering layer is called
cuticle
Hair Growth
• Hair alternates between periods growth
and rest
• Hair on head grows approximately ½” per
month
• Hair lives about 2-6 years before dying
and being shedded
• New hair normally replace lost ones
• Cutting or shaving does not stimulate hair
growth and does not continue to grow after
death
Appearance of Hair
• Deposits in the hair is varying amounts of
melanins. Amount, type and distribution
determines hair color
• Varying amounts of eumelanin in the cortex or
medulla can produce shades of blond and
brunette hair
• Pheomelanin give hair a reddish tint
• Advancing age can produce white (containing no
pigment at all)
• White hair results from failure to maintain
melanocytes in hair follicle
Appearance of Hair
• Shape of shaft determines if hair is straight or
wavy
• Straight hair has round, cylindrical shaft
• Wavy hair has a flat shaft that is not as strong
• Two or more sebaceous glands secret sebum,
(oily substance) into hair follicle
• Sebum lubricates and conditions hair to keep it
from becoming dry and brittle (lipid containing
conditioners help reduce damage also)
Appearance of Hair
• Genes for baldness are inherited
• Common or male pattern baldness can
occur when gene is inherited and
testosterone is present
• The drug minoxidil can slow or even stop
baldness but the drug is expensive and
must be continued for life and it does not
always produced dramatic effect hopped
for
Nails
• Heavily keratinized epidermal cells
• Visible part is called nail body
• The rest of nail or root lie hidden by a fold
of skin bordered by the cuticle.
• The white crescent-shaped area is called
lunula
• Under nail is a layer of epithelium called
nail bed
• Nail bed contains abundant blood vessels
and thus appears pink through nail
Nails
• Cyanosis will appear at the nail bed first so
nail beds are monitored during surgery in
case of a sudden drop in oxygenation
• Nails grow by mitosis in the stratum
germinativum beneath the lunula
• Nails grow an average 0.5 mm a week
(fingernails grow faster than toenails)
• Nails grow faster in the summer than in
the winter
Skin Glands
• 3 types of microscopic glands
–Sweat
–Sebaceous
–ceruminous
Skin Glands
Sweat Glands
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Also called sudoriferous glands
Most numerous skin gland
Can be classified as eccrine or apocrine
Eccrine
– Most numerous, important and widespread
– Distributed over total body surface with the
exception of lips, ear canal, glans penis and
nail beds
– Simple, coiled, tubular type of gland
Skin Glands
Sweat Glands
• Eccrine
– Most numerous, important and widespread
– Distributed over total body surface with the
exception of lips, ear canal, glans penis and
nail beds
– Simple, coiled, tubular type of gland
– Produce perspiration or sweat rich in salts,
ammonia, uric acid, urea and other waste
products
Skin Glands
Sweat Glands
• Eccrine
– Besides eliminating waste sweat helps
maintain core temperature
– Histologists estimate that a single square inch
of skin on the palms contain about 3000
sweat glands
– Actual secretory portion is in the
subcutaneous layer but the ducts travel
through dermis and epidermis to open to the
outside
Skin Glands
Sweat Glands
• Apocrine
– Larger than eccrine glands
– Located deep in subcutaneous in axilla (armpit),
areola of the breast and pigmented area around anus
– Connected with hair follicles
– Classified as simple, branched tubular glands
– Enlarge and begin to function at puberty. In females,
secretions changes are linked to menstrual cycle
– Produce more viscous and colored secretion than
eccrine glands
– Odor is linked to bacteria on the skin
Skin Glands
Sebaceous Glands
• Secrete oil (sebum) for hair and skin
• Helps prevent excessive water loss from skin
• Rich in triglycerides, waxes, fatty acids and
cholesterols
• Sebum has antifungal properties
• Secretions increase during adolescence due to
increase in blood levels of sex hormones
• Pimples are accumulated sebum in enlarged
sebaceous gland ducts
• Oxidation causes sebum to darken in a
blackhead
Skin Glands
Ceruminous Glands
• Modified apocrine glands
• Simple coiled tubular glands with excretory
ducts that open to surface skin of external
ear canal
• Secretion form a brown waxy substance
called cerumen
• Protects skin from dehydrations but can
harden, causing blockage which can result
in hearing loss
Review
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Identify pigment that determines hair color
Appendages of skin
Two types of sweat glands
Function of sebum
Skin Disorders
Skin Disorders
• Any disorder of the skin can be called
dermatosis (skin conditions)
• Inflammation of the skin is called
dermatitis
Skin Infections
Impetigo
• Highly contagious bacterial infection
• Caused by staphylococcus or
streptococcus
• Occurs most often in young children
• Starts as reddish discoloration (erythema)
but soon develops into blisters and
yellowish crust
• Can be systemic
Tinea
• Fungal infection of the skin
• Include ringworm, jock itch, and athlete’s
foot
• Signs include erythema, scaling and
crusting
• Typically forms a round rash that heals in
the center to form a ring
• Treated with antifungal
• Requires moist environment to grow
Warts
• Caused by papillomavirus
• Nipple like neoplasm of the skin
• Most are benign but can transform to
malignant
• Can be passed on by contact
• Can be removed by freezing, drying, laser
or chemicals
Boils
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Also called furuncles
Local staphylococcus infection
Large, inflamed, pus-filled lesion
Group of untreated boils can fuse into
larger carbuncle
Skin Cancer
Skin Cancer
• Most common form of cancer
• Two forms basal cell carcinoma and
squamous cell carcinoma account for 95%
of reported skin cancer cases
• Very responsive to therapy
• Very seldom metastasize
• If left untreated can cause significant
damage to adjacent tissue
• Malignant melanoma has tendency to
spread
Basal Cell Carcinoma
• Most common form of skin cancer
• Begins in cells at the base of the
epidermis
– Basale Stratum
• Most often appears on nose or face
• Can appear at any age but increase after
age 40
• Rarely metastasize but can cause severe
damage to adjacent normal tissue
Squamous Cell Carcinoma
• Slow growing
• Arises from the epidermis
• Occurs more frequently in middle-age or
elderly
• Typically found on sun exposed areas
– Forehead, back of hands, scalp, top of ears
Malignant Melanoma
• Most deadly of all skin cancers
• Shown steady increase in the last 20
years
• Highest incidence found in older
individuals with light skin, eyes and hairs,
does not tan well and have suffered from
severe sunburns
• Sometimes develops from pigmented
nevus (mole)
Malignant Melanoma
• Moles must be checked periodically (use
“ABCD” rule of self exam)
• Asymmetry
– Benign moles are usually symmetrical
• Border
– Benign moles have distinct border
• Color
– Benign moles tend to be evenly colored
• Diameter
– When exhibiting “ABC” changes a malignant mole is
usually larger than 6mm or ¼ “
Malignant Melanoma
• Vaccines are currently being tested
• The main cause is UV radiation
• UV radiation damages DNA in skin cells
causing mutations or mistakes in mitosis
• Can be genetic
Kaposi Sarcoma
• Rarer skin cancer
• Appears in cases of AIDS or other immune
deficiencies
• First appears as purple papules and
quickly spreads to lymph nodes and
internal organs
• Believed to be caused by a virus
Vascular and
Inflammatory
Skin Disorders
Skin Disorders
• Decubitus Ulcer: Pressure sore (bed sore)
– Caused be irritation to skin form lying still or
being bed ridden
• Uticaria or hives (allergic reaction)
•Raised red lesions called wheals
•Caused by leakage of fluid from
skin’s blood vessels
•Severe itching
Skin Disorders
• Scleroderma
– Means “hard skin”
– Autoimmune disease that effects blood
vessels and connective skin tissue
– Starts as mild inflammation and then develops
into patch of yellow hardened skin (usually
localized)
• Psoriasis
– Chronic inflammatory disorder
– Cutaneous inflammation
– Silver colored scaly lesion
Skin Disorders
• Eczema
– Most common inflammatory disorder of the
skin
– Bumps, blisters and crust
– Not disease but a symptom of underlying
problem
– Can be caused by allergic reaction
– Poison Ivy can cause
Abnormal Body
Temperature
Fever
• Unusually high body temp (systemic
inflammatory response)
• Chemicals called pyrogens causes
thermostatic control of hypothalmus to
produce fevers
• Chills
• Enhance body immune response
• Best to let fever break on own
Malignant Hyperthermia
• Inherited condition
• Abnormally increased body temp
(hyperthermia)
• Muscles get rigid when exposed to certain
anesthetics or muscle relaxants
• Drug dantrolene prevents or relieves
condition by inhibiting heat producing
muscle contractions
Heat Exhaustion
• Occurs when body loses large amount of
fluid from heat mechanisms
• Loss of water and electrolytes can cause
weakness, dizziness, nausea, muscle
cramps and possibly loss of
consciousness
• Treated with rest in cool place and fluid
replacement
Heat Stroke/Sunstroke
• Severe, sometimes fatal
• Inability of body to maintain normal temp
in warm environment
• Factors include age, disease, and drugs
• 105° or higher, tachycardia, headache, hot
dry skin, confusions, convulsions or loss of
consciousness
• Body must be cooled and fluids replaced
immediately
Hypothermia
• Inability of body to maintain normal temp
in extremely cold environments
• 95° or lower, shallow slow respirations,
faint slow pulse
• Treated by slowly warming body
Frostbite
• Local damage to tissue from extreme cold
• Damage results fro formation of ice
crystals and reduction in local blood flow
• Necrosis (tissue death) and gangrene
(decay of dead tissue) can result
Burns
Body Surface Estimation
• Severity of burn is determined by depth
and coverage of burn
• Determined by “Rule of Palms” or “Rule of
Nines”
• Using the rule of palms, the surface of the
patient's palm represents approx 1% of
body surface area.
Body Surface Estimation
• “Rule of Nine”
– Body divided into 11 areas of 9%
– Area around genitals (perineum) representing
additional 1% of body
– Small children use Lund-Browder chart
Age in years
0
1
5
10 15 Adult
A-head (back or front)
9
½
8
½
6
½
5
½
4
½
3½
B-1 thigh (back or
front)
2
¾
3
¼
4
4
¼
4
½
4¾
C-1 leg (back or front)
2
½
2
½
2
¾
3
3
¼
3½
1st Degree Burn
•
Can peel but no blistering
•Tissue damage in minimum
•Minor irritation
•Also called partial thickness burn
2nd Degree Burn
• Can damage glands and hair follicles
•Scaring is common
•Can have white charred skin
•Can produce shock
3Rd Degree Burn
• Tissue death extends below hair follicles and
glands
•Fourth degree involves muscle and bone
•Pain may not be apparent due nerve damage
•Scaring is a serious problem
•
http://video.google.com/videoplay?docid=1856678610844928019&ei=bEbiStjMO5arAKNz7DoDA&q=skin+tissue&hl=en#