Download Integumentary System and Body Temperature

Integumentary System and
Body Temperature
Chapter 7
Integumentary System
• Includes
– Skin
– Accessory
structures (sweat
glands, oil glands,
hair and nails)
– Subcutaneous
tissue
Functions of the Skin
• Acts as a barrier- keeps harmful
substances out and retains water and
electrolytes
• Protects internal structures from injury,
chemicals, sunlight, burns and pathogenic
microorganisms
• Excretes water, salt and trace amounts of
waste products (ex. urea)
Functions of the Skin
• Synthesizes vitamin D (from sunlight;
necessary for the absorption of calcium
from the digestive tract)
• Contains sensory receptors for touch,
pressure, pain, and temperature (helps
detect information about the environment)
• Important for regulation of body
temperature
Structure of the skin
• Called integument (from the Latin word
meaning “to cover”); also called
cutaneous membrane
• The largest organ in the body
• Outer layer is the epidermis
• Inner layer is the dermis
• The dermis is anchored to the
subcutaneous layer
Epidermis
• Thin outer layer of skin
• Composed of stratified squamous
epithelium
• Avascular- receives oxygen and nutrients
from the blood vessels of the dermis
• The “dead layer” of the skin
Epidermis
• Stratum germinativum
– Located on top of the dermis; has a rich blood
supply
– Cells are continuously dividing and producing
millions of cells per day
– New cells push older cells up toward the
surface of the epithelium; as cells move away
from the dermis they lose their blood supply
and begin to die; these cells go through
keratinization- keratin (tough protein) is
deposited in the cell.
Epidermis
• Stratum germinativum
– Keratin hardens and flattens the cells; makes
the skin waterproof and provides protection
• Stratum corneum
– Surface layer of the epidermis
– Composed of approx. 30 layer of dead,
flattened, keratinized cells
– Dead cells are continuously sloughed off;
replaced by new cells moving up from the
deeper layers; complete new skin every
month
FYI
• Humans shed about 600,000 particles of
skin every hour- about 1.5 pounds a year
(that’s 105 lbs by the age 70!)
This Bernese Mountain
Dog weighs 105 lbs!
Water loss
• Approx. 500cc of water is lost every day
through the skin
• Insensible perspiration is sweat that
evaporates from the skin before it is
perceived as moisture on the skin; if the
epidermis is damaged (as in burns) the
rate of water loss through insensible
perspiration increases tremendously
Dermis
• Located under the epidermis and
composed of dense fibrous connective
tissue
• Contains collagen and elastin fibers
surrounded by gel-like intercellular matrix
(accounts for stretching of skin during
pregnancy and weight gain)
• The “living layer” of the skin
Dermis
• Thickness of the epidermis and the dermis
varies according to location- thinnest at
eyelids, thickest on palms and soles
• Accessory structures (hair, nails, glands)
are embedded in the dermis
• Dermis contains blood vessels, nervous
tissue (sensory receptors) and muscle
tissue
Subcutaneous Layer
• Lies below the dermis
• Not considered part of the skin; also called
the hypodermis
• Composed of loose connective and
adipose tissue
• Purpose: provided insulation and protects
against extreme temperature change;
anchors the skin to underlying structures
Subcutaneous Layer
• Drugs are often injected into the
subcutaneous layer because it has a rich
blood supply
“Skin popping” heroin
The skin, drugs and chemicals
• The skin is capable of absorbing many
chemicals- both medicines and dangerous
chemicals
• Transdermal (trans-) administration uses
the skin to absorb drugs into the blood
stream; allergy testing can be done using
intradermal (intra-) injections
Nitroglycerin patch
The skin, drugs and chemicals
• Toxins can also be absorbed through the
skin; these include pesticides, cleaning
chemicals, and poisons (remember
anthrax?)
Cutaneous anthrax
Skin Color
• Skin color is determined mostly by
genetics, but also physiological factors
and sometimes disease
• Epidermal layer contains melanocytes;
these cells secrete the skin darkening
pigment melanin
• The more melanin secreted, the darker the
skin
Skin Color
• Everyone has roughly the same number of
melanocytes
• Differences in color occur because of the
amount of melanin secreted
• Exposure to UV rays increases the
amount of melanin secreted (think tanning
beds)
Differences in skin color
Malfunctioning Melanocytes
• If melanocytes completely fail to secrete
melanin, albinism occurs (people with the
condition are called albinos)
• Skin, hair and the iris of the eyes contain
no pigment
Malfunctioning Melanocytes
• Vitiligo occurs when there is patchy loss
of pigment in the skin
Malfunctioning Melanocytes
• Small areas of concentrated melanin are
moles or freckles; moles that change
appearance should be checked for
melanoma (-oma tumor)
Skin Color
• Skin also contains a yellow color- carotene
(most of the yellow color is usually hidden
by the melanin)
• Some skin appears to have a pinkish tint
because there is so little melanin that the
blood vessels of the dermis are visible
• Lack of oxygen in these blood vessels
causes cyanosis (cyano-); a bluish
discoloration
Cyanosis of the nailbeds
Skin Color
• Jaundice is a yellow discoloration of the
skin and sclera resulting from an
accumulation of bilirubin (usually from liver
disease); newborns can also have
jaundice
Newborn with jaundice
Bili lights used to treat newborn
jaundice
Skin Color
• Argyria is a bluish-gray discoloration of
the skin that results from an accumulation
of colloidal silver in the skin (used to be
found in cold and allergy medications as
well as some skin creams- not FDA
approved)
Example of argyria
Accessory Structures
Hair
• According to the text, the main function of
hair is to sense insects on the skin before
they sting
• Hair also serves to conserve heat and
insulate the body; provides some
protection
• Most of the body is covered with hairpalms, soles, lips, external reproductive
organs
Hair
• Eyebrows and eye lashes protect the eyes
from dust and perspiration
• Nasal hairs and ear hairs trap dust and prevent
it from entering the lungs
Hair
• Hair growth is regulated by testosterone
and estrogen; the role of estrogen is not
well understood. Testosterone stimulates
hair growth; during puberty, the surge of
hormones stimulates hair growth in the
axillary and pubic areas
Hair
• Excessive testosterone in females causes
hair growth in males patterns (facial hair,
abdomen, hands etc.). This condition is
called hirsutism
Hair
• Structure of the hair:
– Shaft (visible part above the skin)
– Root (part that extends from the dermis to the
surface)
– Follicle (downward extension of epithelial
cells; opening in the skin that holds the hair)
– Hair is formed in the same way as the outer
layer of the skin; new cells are formed and are
pushed to the outer layer- the cells die and
become keratinized
Hair
• Hair color is
determined by
genetics- the amount
and type of melanin;
dark hair (lots of
melanin), blonde hair
(little melanin) white
hair (no melanin),
grey hair (mixture),
red hair (melanin
containing iron)
Hair
• The shape of the hair shaft determines the
appearance of the hair- round shaft,
straight hair; oval shaft, wavy hair; flat
shaft, curly or kinky hair
Hair
• Hair helps to conserve body heat by
“standing up” to trap a layer of air near the
skin surface
• Individual hairs are pulled perpendicular to
the skin by tiny muscles called arrector
pili which are attached to the hair follicle;
the skin is pulled up slightly which creates
“goosebumps”
arrector pili
Hair
• Hair loss is called alopecia
• The most common type of hair loss is
male-pattern baldness (androgenic
alopecia)
Nails
• Thin plates of stratified squamous
epithelium that contains a very hard form
of keratin
• Found on the distal end of fingers and toes
and serve to protect from injury
Nails
• Structure
– Free edge
– Nail body
-Nail root
-Lunula
Nails
• Nails appear pink because of blood
vessels in the dermis
• Clubbing of the nails occurs when there is
an insufficient blood supply for a long
period of time (often seen in long-time
heavy smokers)
Glands
• Two major glands associated with the skin
• Sebaceous glands (oil glands)
– Associated with hair follicles; found on the
body where there is hair
– Secrete sebum lubricates and waterproofs
– In the fetus, secretes vernix caseosa that
covers the fetus and offers protection from
amniotic fluid
Glands
• When accumulated sebum blocks a
sebaceous gland and is exposed to air
and dries out, it turns black and forms a
blackhead.
• If it becomes infected with staphylococci, it
becomes a pustule, or a pimple
Glands
• Sudoriferous (sweat) glands
– Located in the dermis, secrete sweat
– Sweat is released through ducts that open
onto the skin as pores
– Two types: apocrine glands (associated with
hair follicles and found in the axilla and pubic
areas); eccrine glands (found all over the
body, not associated with hair)
Glands
• Apocrine glands secrete sweat in response to
emotional stress, fear, pain or sexual arousal
– Causes body odor when sweat is broken down by
bacteria on the skin surface
• Eccrine glands secrete sweat in order to cool
the body; as moisture evaporates, heat is lost
– Mammary glands and ceruminous glands are
modified sweat glands
Body Temperature
Body Temperature
• Normal body temperature ranges from 97°
to 100° (average is 98.6°F)
• Fluctuates throughout the day, lower in the
morning, higher in the afternoon
• Core temp (cranial, thoracic & abdominal
cavities)
• Shell temp (skin and mouth)
Body Temperature
• Body temperature is maintained by
balancing heat production and heat loss
(remember homeostasis?)
• This balance is known as
thermoregulation
• Excessive changes in body temperature
can be severe, even fatal
• Hyperthermia vs. hypothermia
Heat Production
• Heat is thermal energy
• Produced by the millions of chemical
reactions occurring in the body
• The heat produced by metabolism is the
basis for body temperature
• At rest, most of the body’s heat is
produced by the muscles, the liver and
endocrine glands
Heat Production
• Heat production is affected by food
consumption, hormone secretion and
physical activity
• Exercise greatly increases heat
production; thyroid hormones influence
heat production (thyroid storm can be
lethal)
Heat Loss
• Most heat 80% is lost through the skin, the
rest is lost through the respiratory tract
and excretion of waste
• Four means of heat loss
– Radiation
– Conduction
– Convection
– Evaporation
Heat Loss
• Radiation
– Heat loss from warm object to surrounding air
• Conduction
– Heat loss from warm object to cooler object
(contact); cooling blankets
• Convection
– Loss of heat due to air currents
• Evaporation
– Heat loss when liquid turns to gas (sweat on
skin)
radiation
convection
conduction
evaporation
Temperature Regulation
• Thermostat of the body is the
hypothalamus; senses changes in body
temperature and sends information to the
skin and skeletal muscle
• Temperature elevation
– Blood vessels dilate, allowing more blood to
flow to the skin; this transfers heat from
deeper tissues to the surface
Temperature Regulation
• Temperature elevation
– Sweat glands are activated
– When sweat evaporates from the skin, heat is lost
• Temperature decrease
– Blood vessels constrict, reducing blood flow to the
skin; traps blood and heat in the deeper tissues
– Sweat glands become less active
– Shivering occurs, producing heat from muscle
contractions
Temperature Regulation
• Intense heat can be dangerous to the
body
– Heat cramps
– Heat exhaustion
– Heat stroke (thermoregulatory failure)
• Hypothermia slows metabolism and has
been shown to improve patient outcomes
in cardiac arrest (think cold-water
drowning); but temps below 95° can be
fatal
Temperature Regulation
• Thermoregulation is difficult for newborns
– Large surface area increases heat loss
– Thin layer of subcutaneous fat
– Neonate cannot shiver
• Neonates have brown adipose tissue
(BAT) which produces a large amount
heat when metabolized; this is called
nonshivering thermogenesis
Burns
Burns
• Classified according to depth of the burn
and the extent of the surface area burned
• Partial thickness
– First degree (only epidermis involved)
– Second degree (epidermis and dermis)
• Full thickness (third degree)
– Epidermis, dermis and underlying structures
are destroyed
Burns
• First degree burns
– Red, painful and slightly edematous
Burns
• Second degree burns
– Redness, pain, edema, blisters
Extensive burn with marked leakage (extravasation) of fluid into the burned area
leading to formation of large blisters.
Burns
• Third degree burns
– May appear brown, black or deep red;
painless (area around the burn is very painful)
Third Degree Burns
Burns
• Rule of Nines
– Allows for
estimation of
body surface
area affected by
burn
– Parkland formula
is based on the
rule of nines
Fluid Requirements = TBSA burned(%) x Wt (kg) x 4mL
Give 1/2 of total requirements in 1st 8 hours, then give 2nd half over next 16 hours.
Burns
• Eschar
– Associated with severe burns
– Dead, burned tissue that forms a thick,
inflexible scar tissue layer over the burned
area
– Can act like a tourniquet and cut blood supply
to an area, or can restrict breathing if on the
chest
– Can breed infection leading to deadly sepsis
in the patient
– Escharotomy is performed to release the
tissue
Eschar (decubitus ulcer on the
heel)
Approximate lines for chest escharotomy
Burns
Some disease and disorder
terms…
Normal skin changes associated with the aging process- loss of
subcutaneous fat, thinning of dermis, transparent appearance of skin
Decubitus Ulcers
Staging Ulcers
Stage 1
Stage 2
Skin red, intact
Skin breakdown occurs
Staging Ulcers
Stage 3
Stage 4
Deeper than stage 2,
extending into dermis and
subcutaneous layers
Severe tissue loss; muscle and bone
may be involved
Contact dermatitis
Alopecia Aereata (patchy loss of hair)
Alopecia totalis- total loss of scalp hair
Alopecia universalis- complete loss of body
hair (note lack of eye brows and eye lashes
Furuncle: inflamed hair follicle, also called a
boil
Ecchymosis: fancy-schmancy
word for bruise; technically, it is a
superficial discoloration caused by
blood in the tissue
Ecchymosis
Recurrent oral herpes caused by herpes virus type 1.
Herpes
Zoster
(also called
shingles)
Shingles (affecting
different branches of the
trigeminal nerves CN V)
Debridement- removal of damaged or necrotic tissue from a
wound
Keloid Scar (caused by
excessive fibrosis)
Branding (fraternity hazing)
Scarification
Cellulitis of the finger and face/ periorbital regions
Eczema
Eczema
• A form of dermatitis, or inflammation of the epidermis.
The term eczema is broadly applied to a range of
persistent skin conditions. These include dryness and
recurring skin rashes which are characterized by one or
more of these symptoms: redness, skin edema
(swelling), itching and dryness, crusting, flaking,
blistering, cracking, oozing, or bleeding. Areas of
temporary skin discoloration may appear and are
sometimes due to healed lesions, although scarring is
rare. In contrast to psoriasis, eczema is often likely to be
found on the flexor aspect of joints.
(from wikipedia)
Psoriasis (red patches covered
with silver scales)
Psoriasis
•
•
•
Chronic, non-contagious autoimmune disease which affects the skin and
joints. It commonly causes red scaly patches to appear on the skin. The
scaly patches caused by psoriasis, called psoriatic plaques, are areas of
inflammation and excessive skin production. Skin rapidly accumulates at
these sites and takes on a silvery-white appearance. Plaques frequently
occur on the skin of the elbows and knees, but can affect any area including
the scalp and genitals. In contrast to eczema, psoriasis is more likely to be
found on the extensor aspect of the joint.
The disorder is a chronic recurring condition which varies in severity from
minor localized patches to complete body coverage. Fingernails and
toenails are frequently affected (psoriatic nail dystrophy) and can be seen
as an isolated finding. Psoriasis can also cause inflammation of the joints,
which is known as psoriatic arthritis. Ten to fifteen percent of people with
psoriasis have psoriatic arthritis.
The cause of psoriasis is not known, but it is believed to have a genetic
component. Factors that may aggravate psoriasis include stress, withdrawal
of systemic corticosteroid, excessive alcohol consumption, and smoking.
There are many treatments available, but because of its chronic recurrent
nature psoriasis is a challenge to treat
(from wikipedia)
Diaphoresis
(excessive sweating)
NCLEX Question:
•
1.
2.
3.
4.
A nurse is reading the physician’s progress
notes in the client’s record and sees that the
physician has documented “insensible fluid
loss of approximately 800 mL daily”. The nurse
understands that this type of fluid loss can
occur through:
the skin
urinary output
wound drainage
the gastrointestinal tract
Rationale
• 1. Insensible loss of fluid occurs through
the skin and the lungs. The person is not
aware of these losses.
NCLEX Question:
•
1.
2.
3.
4.
Which of the following would be the
anticipated therapeutic outcome of an
escharotomy procedure performed on a
circumferential arm burn?
The return of distal pulses
Decreasing edema formation
Brisk bleeding from the injury site
The formation of granular tissue
Rationale
• 1. Escharotomies are performed to relieve
pressure from the edema that
accumulates under the inflexible eschar in
a circumferential burn. This pressure can
inhibit arterial circulation.