Integumentary System and Body Temperature

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Integumentary System and Body Temperature

• Chapter 7

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Integumentary System

• Includes
• Skin
• Accessory structures (sweat glands, oil glands,
  hair and nails)
• Subcutaneous tissue

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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)

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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

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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

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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

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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.

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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

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FYI

• Humans shed about 600,000 particles of skin every
  hour- about 1.5 pounds a year (thats 105 lbs by
  the age 70!)

This Bernese Mountain Dog weighs 105 lbs!
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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

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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

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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

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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

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Subcutaneous Layer

• Drugs are often injected into the subcutaneous
  layer because it has a rich blood supply

Skin popping heroin
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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
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The skin, drugs and chemicals

• Toxins can also be absorbed through the skin
  these include pesticides, cleaning chemicals, and
  poisons (remember anthrax?)

Cutaneous anthrax
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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

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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)

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Differences in skin color
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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

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Malfunctioning Melanocytes

• Vitiligo occurs when there is patchy loss of
  pigment in the skin

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Malfunctioning Melanocytes

• Small areas of concentrated melanin are moles or
  freckles moles that change appearance should be
  checked for melanoma (-oma tumor)

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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

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Cyanosis of the nailbeds
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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

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Bili lights used to treat newborn jaundice
Newborn with jaundice
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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)

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Example of argyria
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Accessory Structures
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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 hair- palms,
  soles, lips, external reproductive organs

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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

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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

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Hair

• Excessive testosterone in females causes hair
  growth in males patterns (facial hair, abdomen,
  hands etc.). This condition is called hirsutism

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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

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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)

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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

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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

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arrector pili
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Hair

• Hair loss is called alopecia
• The most common type of hair loss is male-pattern
  baldness (androgenic alopecia)

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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

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Nails

• Structure
• Free edge -Nail root
• Nail body -Lunula

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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)

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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

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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

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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)

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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

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Body Temperature
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Body Temperature

• Normal body temperature ranges from 97 to 100
  (average is 98.6F)
• Fluctuates throughout the day, lower in the
  morning, higher in the afternoon
• Core temp (cranial, thoracic abdominal
  cavities)
• Shell temp (skin and mouth)

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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

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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 bodys heat is produced by
  the muscles, the liver and endocrine glands

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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)

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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

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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)

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radiation
conduction
convection
evaporation
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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

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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

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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

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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

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Burns
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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

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Burns

• First degree burns
• Red, painful and slightly edematous

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Burns

• Second degree burns
• Redness, pain, edema, blisters

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Extensive burn with marked leakage
(extravasation) of fluid into the burned area
leading to formation of large blisters.
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Burns

• Third degree burns
• May appear brown, black or deep red painless
  (area around the burn is very painful)

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Third Degree Burns
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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.
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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

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Eschar (decubitus ulcer on the heel)
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Approximate lines for chest escharotomy
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Burns
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Some disease and disorder terms
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Normal skin changes associated with the aging
process- loss of subcutaneous fat, thinning of
dermis, transparent appearance of skin
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Decubitus Ulcers
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Staging Ulcers
Stage 1 Skin red, intact
Stage 2 Skin breakdown occurs
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Staging Ulcers
Stage 3 Deeper than stage 2, extending into
dermis and subcutaneous layers
Stage 4 Severe tissue loss muscle and bone may
be involved
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Contact dermatitis
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Alopecia Aereata (patchy loss of hair)
Alopecia totalis- total loss of scalp hair
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Alopecia universalis- complete loss of body hair
(note lack of eye brows and eye lashes
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Furuncle inflamed hair follicle, also called a
boil
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Ecchymosis fancy-schmancy word for bruise
technically, it is a superficial discoloration
caused by blood in the tissue
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Ecchymosis
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Recurrent oral herpes caused by herpes virus type
1.
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Herpes Zoster (also called shingles)
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Shingles (affecting different branches of the
trigeminal nerves CN V)
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Debridement- removal of damaged or necrotic
tissue from a wound
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Keloid Scar (caused by excessive fibrosis)
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Branding (fraternity hazing)
Scarification
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Cellulitis of the finger and face/ periorbital
regions
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Eczema
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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)

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Psoriasis (red patches covered with silver scales)
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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)

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Diaphoresis (excessive sweating)
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NCLEX Question

• A nurse is reading the physicians progress notes
  in the clients 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

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Rationale

• 1. Insensible loss of fluid occurs through the
  skin and the lungs. The person is not aware of
  these losses.

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NCLEX Question

• 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

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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.

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