Transcript Slide 1

The Integumentary System
(skin)
Skin
• is the largest system
of the body
–16% of body weight
–you have 21 square feet of it
–it weighs ~9 pounds
–it contains more than 11 miles of blood
vessels
–you shed 50,000 cells every MINUTE!!!
Functions of Skin
• Protects you from
• infection
• desiccation
• UV rays
• Important for
–temperature regulation
(insulation and
evaporation)
• it releases 3 gallons of sweat each day!
–excretion
of salts, water, and organic
wastes (glands)
Functions of Skin
• Synthesizes vitamin D3
–which you need to extract calcium from your
diet and incorporate it into your bones!
• Detects sensations
–touch, pressure, pain, and temperature: as a
huge sensory receptor, the skin is your
constant communication with the outside
world
First Line of Defense!
Skin is one huge sensory organ! It is
responsible for sending information to the
brain to protect the body from injury.
–Nerve sensory
receptors for
•pain
• touch
•vibration
• pressure
•temperature
Components of Skin
• Outer Epidermis
:
– epithelial tissue
• stratified squamous keratinized
• Inner Dermis
:
– connective tissue
• loose and dense
Types of Epidermis
• Thin skin :
–Covers most of the body
– This skin is also hairy skin for the
most part
–Has only a few layers of dead surface
cells
• Thick skin :
– Covers the palms of the hands and soles
of the feet
–Has many layersof dead surface cells
Dermis
• Source of blood and
nutrients for the
epidermis
• Composed of 2 layers:
– “papillary”layer:
• loose connective tissue
– “reticular”layer:
• dense irregular connective
tissue
• Directs the characteristics
of the epidermis
Dermis
A. Overall Features
1. thick in some areas, thinner in others
2. contains blood supply, nerves, glands, hair follicle
B. Papillary Layer (Region)
1. loose connective tissue - much "elastin"
2. dermal papillae cause ridges in the epidermis superficially
3. Meissner's corpuscles - sense organ for deep touch
4. small capillaries supply O + nutrients
C. Reticular Layer (Region)
1. dense, irregular connective tissue "collagen"
2. collagen fibers interlace in net-like fashion
3. contains: adipose, hair follicle, nerves, glands
4. subcutaneous layer attaches skin to tissue below
a. Paccinian corpuscles - sense pressure change
The Hypodermis
• AKA subcutaneous tissue
or superficial fascia:
– NOT a part of the “skin”
– Deep to the dermis
– Composed of loose
connective tissue (primarily
fat)
– Location of hypodermic
injections
Major Cell Types of the Epidermis
• Keratinocytes –: the most abundant cells
in the epidermis
– synthesize and secrete keratin(a waxy hydrophobic
protein that creates a water barrier)
– responsible for the “keratinized”epithelium
fibrous structural proteins. Keratin is the key structural material making up the outer layer of
human skin. It is also the key structural component of hair and nails.
Keratin monomers assemble into bundles to form intermediate filaments, which are tough and
insoluble and form strong unmineralized tissues
Melanocytes : – secrete the pigment melanin
• protects the keratinocytefrom the sun
Langerhans and dendritic cells
– antigen-presenting cells
for the immune
response (a type of macrophage)
– decrease in # with a sun tan!
:
Layers of the Epidermis and the Life Cycle
of the Keratinocyteas it moves towards the
surface:
Layers:
cornified
lucid
granular
spiny
basal
Layer of Epithelium
Epidermis (epithilial tissue)
1. stratum corneum
2. stratum lucidum – only palms and
soles – “clear”
3. stratum granulosum
4. stratum spinosom
5. stratum basale
Basal Layer
• Contains the stem cells
for keratinocytes
– 1 layer thick
– also contains melanocytes
– This is where mitosis
occurs (about every 15-30
days)
• (psoriasis = ↑mitotic activity
(turnover every 7 days)
– Cells are attached to
thebasement
membrane (by adherens
junctions)
• hence the name of this layer
The Basal Layer meets the underlying
Dermis
• Epidermal ridges
(e.g.,fingerprints)
• Dermal papillae (tiny
mounds):
–strengthen
attachment between
epidermis and dermis
Stratum spinosum
Spiny Layer
• Contains 2–10 layers of
keratinocytes attached to
each other by many
adherens junctions
• As the cells move away
from the basal layer, they
– begin to shrink
• further from source of nutrition
– are still connected to
adjacent cells by adhering
junctions
– these connections look like
spines
• hence the name of this
layer
Stratum granulosum
Granular Layer
• Contains 2-5 layers of
keratinocytes
• By this point in their life
cycle, keratinocytes are
producing significant
amounts of keratin
– which accumulates in and
around the cells
– they now take on a
granular appearance
• hence the name of this
layer
• The cells are now far
enough away from the
source of nutrition that they
are dehydrating and
flatteningas well
Stratum lucidum
Lucid Layer
• The clear (or “lucid”,
hence the name of this
layer) layer
• Contains 1-5 layers of
dying keratinocytes
• The cells are now very
flat so it is difficult to see
individual cells
• The cytoplasm appears
homogeneous all the
major organelles have
died and degenerated
Stratum corneum
Cornified Layer
• Contains 10 -100’s of
layers of dead cells
– depending on whether
thick or thin skin
• Basically composed
of flat sheets (scales)
of keratin
• Layers slough off
• (desquamate) here
Skin Color
• Skin color depends on:
– the pigments carotene
:
• Orange-yellow pigment
• Found in orange vegetables
• Accumulates in epidermal cells and fatty tissuesof the dermis
• Can be converted to vitamin A
– and
melanin
:
• Yellow-brown or black pigment
• Produced by melanocytes in the basal layer
• Transferred to keratinocytes
• Protects DNA in nuclei of keratinocytes from sun (UV) damage
– and blood
circulation (red blood cells)
• Oxygenated red blood contributes to skin color:
– blood vessels dilate from heat, skin reddens
– blood flow decreases, skin pales
Melanocytes
Basal layer
More facts about skin color
• With a tan
–pre-existing melanin darkens
–the rate of new melanin synthesis increases
Illness and Skin Color
• Jaundice :
– buildup of bileproduced by liver
– yellow color
• Cyanosis :
– Bluish skin tint
– Caused by severe reduction in blood flow or
oxygenation
• Vitiligo :
– loss of melanocytes
– loss of color
Accessory Structures
• Originate in the
dermis
• Extend through
the epidermis to
skin surface:
–hair
–nails
–exocrine glands
• sweat
• sebaceous
The sensory receptors in the skin are:
cutaneous mechanoreceptors
Ruffini's end organ (sustained pressure)
Meissner's corpuscle (changes in texture, slow vibrations)
Pacinian corpuscle (deep pressure, fast vibrations)
Merkel's disc (sustained touch and pressure)
Free nerve endings (light touch)
Thermoreceptor (temperature)
Nociceptor (noxious sensations)
Chemoreceptor (sensitivity to chemicals)
• Functions:
– protects and
insulates
– associated with
touch receptors
• Composed of dead cells
that are heavily
keratinized
• Hair color is produced by
melanocytes at the hair
papilla
• Associated with:
– Arrector pili:
• smooth muscle
• causes hairs to stand up
producing “goose bumps”
– Sebaceous glands
Hair
A Hair Shaft
External layer
Internal layer
Interesting hair facts
• Hairs grow discontinuously
–There are periods of growth and periods of
rest
•Scalp:
– growth periods may last many years
– rest periods average 3 months
• Hair in different regions of the body grows
at different rates
Nails and Nail Production
•Nails protect fingers
and toes :
– composed of dead
cells packed with keratin
– metabolic disorders
can change nail structure
• Nail production
occurs in a deep
epidermal fold near
the bone called the
nail root
Interesting nail facts
• Transparency of the
nail provides a useful
window re amount of
oxygen in the blood!
–Indicator used during
surgery
• No nail polish!
Exocrine Glands
• Sweat glands :
– most are merocrine
glands:
• found in both thick and thin
skin
• secrete water and
ions
– apocrine glands:
• found in axillary, areolar
and anal regions only
• secrete apical
portion of the cell
with the water and ions
• associated with body
odor
• active at puberty
Exocrine Glands
•
Sebaceous oil glands:
– holocrine glands:
whole cell is
secreted
– associated with thin
skin only
– mainly associated
with hair follicles
– begin to function at
puberty
• lubricate and
protect the
epidermis
• inhibit bacteria so can produce the familiar odor of
arm pits
First
Second
(Superficial or Deep)
Third (Full Thickness)
Depth (how
deep the burn is)
Epithelium
Epithelium and top aspects of the dermis
Epithelium and dermis
How the wound looks
No blisters; dry pink
Moist, oozing blisters; Moist, white, pink, to red
Leathery, dry, no elasticity; charred appearance
Causes
Sunburn, scald, flash flame
Scalds, flash burns, chemicals
Contact with flame, hot surface, hot liquids, chemical, electric
Level of Pain
(sensation)
Painful, tender, and sore
Very painful
Very little pain, or no pain
Healing Time
Two to five days; peeling
Superficial: five to 21 days. Deep: 21-35 days
Small areas may take months to heal; large areas need grafting.
Scarring
No scarring; may have discoloration
Minimal to no scarring; may have discoloration
Scarring present
Burns
•
•
•
•
•
•
First degree:
Includes only the outer layer of skin, the epidermis
Skin is usually red and very painful
Equivalent to superficial sunburn without blisters
Dry in appearance
Healing occurs in 3-5 days, injured epithelium peels
away from the healthy skin
• Hospitalization is for pain control and maybe fluid
imbalance
Second Degree
• Second degree: Can be classified as partial
or full thickness.
• Partial thickness
– Blisters can be present
– Involve the entire epidermis and upper layers of
the dermis
– Wound will be pink, red in color, painful and wet
appearing
– Wound will blanch when pressure is applied
– Should heal in several weeks (10-21 days) without
grafting, scarring is usually minimal
Third Degree
•
•
•
•
Third degree:
All layers of the skin is destroyed
Extend into the subcutaneous tissues
Areas can appear, black or white and will be
dry
• Can appear leathery in texture
• Will not blanch when pressure is applied
• No pain
3rd degree full thickness
Fourth Degree
• Full thickness
– Can be red or white in appearance, but will appear
dry.
– Involves the destruction of the entire epidermis
and most of the dermis
– Sensation can be present, but diminished
– Blanching is sluggish or absent
– Full thickness will most likely need excision & skin
grafting to heal
– Extends into bone and muscle
This chart divides the
body surface into
areas, each of which
represents 9 percent.
The "rule of nines" is
generally used for
quick assessment of
the total body surface
area (TBSA) that has
been injured. In
infants and small
children, the surface
area of the head and
neck is greater and
the lower extremity is
smaller than an adult.
Therefore, the LundBrowder chart more
accurately determines
the extent of a burn.
Skin Cancer Facts
• 1/3 of all tumors are of the skin
• Rarely lethal (deadly) if diagnosed early:
–Basal cell carcinoma: easily curable
• derived from cells in the basal layer
–Squamouscell carcinoma:
• derived from cells in the spiny layer
• Most serious and invasive tumors:
–(Malignant) melanoma:
• derived from melanocytes
Any condition resulting in hair loss is called alopecia
• Actinic Keratosis: Precursor to Squamous
Cell Carcinoma
• Rough, red or pink scaly patches on sunexposed areas of the skin,usually <0.5cm in
diameter
• Precurser lesion for squamous cell carcinoma
(Squamous Cell Carcinoma)
• Up to 1% of these lesions can develop into a
Squamous Cell Carcinoma
Ref:http://www.dermatology.ucsf.edu/skincancer/professionals/type
s.aspx
• Basal Cell Carcinoma :
• Raised, pink, waxy bumps that may bleed
following minor injury
• May have superficial blood vessels and a
central depression
• Locally invasive
• Rarely metastasizes
• Organ transplant recipients have a 10-fold
higher risk for Basal Cell Carcinoma
compared to the general population(2)
http://www.dermatology.ucsf.edu/skincancer/professionals/types.as
px
• Melanoma:
• Neoplasm of pigment (melanin) producing cells
• Brown or black skin lesion with irregularities in symmetry, border
and coloration
• Prognosis dependent on depth of invasion
• ~100,000 new cases of melanoma are diagnosed in the United
States each year
– Only 4% of diagnosed skin cancer, but 77% of skin cancer related
deaths
• Organ transplant recipients have a 3 to 4-fold higher risk for
melanoma compared to general population(12)
– Melanoma accounts for ~6% of post transplant skin cancers in
adult transplant recipients(13)
– Melanoma accounts for 12-15% of post transplant skin cancers in
pediatric organ transplant recipients(13)
– Transplant recipients with a pre-transplant history of melanoma
have a high risk of recurrence (~20%)(14)
Quick Facts:
• The most readily cured type of cancer is
basal cell carcinoma
• A condition involving absence or loss of hair
is called alopecia
• Loss of skin color is called vitiligo
• A single celled layer of squamous
epithelium is found lining blood vessels and
alveoli and are called “endothelial” cells
Diabetes
• Exposure to high blood sugar levels
damages the basement membrane of
endothelial cells (sometimes called
basal lamina). This may cause kidney
disease and blindness
The 2 major components of skin
are:
A. dermis and hypodermis
B. epidermis and dermis
C. dermis and subcutaneous layer
D. epidermis and hypodermis
Functions of the skin include:
A. temperature regulation
B. protection from infection
C. synthesis of vitamin D
D. sensory organ
E. all of the above
Thin skin is found in all of the
following locations EXCEPT:
A. back
B. legs
C. arms
D. face
E. palms
The most abundant cell type of
the epidermis is the:
A. melanocyte
B. Langerhanscell
C. fibroblast
D. keratinocyte
E. basal cell
The layer of skin in which
keratinocytes divide is the:
A. cornified layer
B. basal layer
C. granular layer
D. spiny layer
E. lucid layer
The layer of skin in which
keratinocytes slough off is the:
A. cornified layer
B. basal layer
C. granular layer
D. spiny layer
E. lucid layer
Most of your sweat glands:
A. release only water and ions
B. release a part of the cell with the
water and ions
C. release the whole cell with the water
and ions
D. release oil
E. are found in thick skin only
Skin color is determined by:
A. melanin
B. carotene
C. blood
D. none of the above
E. all of the above
What are the 5 layers of the
epidermis?
• Be sure that you can name them in
order and how changes occur which
actually forms these layers.
What is the nature of a
fingernail?
• Know the features of the fingernail
• Know the features of a hair
• Based on the rule of 9s, what percent of the
body surface is occupied by the skin of the
trunk?
• What is meant by 1st degree, 2nd degree and
3rd degree burns?
• What are the three main types of skin cancer
and what are their features?
Damage to the basal lamina due to
untreated diabetes may lead to
kidney failure and what other
malady?
• You have to come up with the answer!