Transcript Document 7321880

Integumentary System
Anatomy & Physiology
Chapter 6
•Skin is the largest organ
•Integument is another name for skin
•Is made up of Hair, Nails, Glands, and Skin
Three Layers of Skin
Epidermis
1.
2.
3.
4.
5.
top/outer layer of skin
epithelial tissue only
stratified squamos
contains NO blood vessels
contains keratinocytes and melanocytes
and Langerhans cells
6. Cell layers are called strata
Epidermis
Stratum corneum (horny
layer)
1. Outer layer of epidermis
2. Forms a barrier between the
outside world and the body’s
inner cells
3. Made up of dead simple
squamous cells
4. Keeps body from losing water
to the outside or taking water
in through the skin
5. No blood vessels and few
sensory receptors are found
in the epidermis
6. Epidermis receives
nourishment from the blood
vessels of the dermis
Epidermis
Stratum lucidum
1. Contains closely packed, clear keratinocyte cells
2. Cells contain a gel-like substance called eleidin.
3. Only present in palms and soles of feet
Epidermis
Stratum granulosum (granular layer)
1.Contains keratohyalin granules, which is used to
form keratin
2. Where Keratinization begins due to the beginning of
the degeneration of cells
3. 2-4 layers deep
Epidermis
Stratum spinosum
(spiny layer)
1. Contains several
layers of manysided cells
2.
Contains
keratinocytes
rich in RNA that
synthesize the
protein keratin,
which provides a
waterproof layer
to the epidermis
epidermis
Epidermis
1.
2.
3.
4.
5.
Stratum basale
Inner layer
(base)
Responsible for
producing new
skin cells
(mitosis)
Protects body
from the sun
(melanocytes)
Single layer of
columnar cells
Contains the
Langerhans
cells of the
immune system
melanocytes
dermis
Epidermal Growth and Repair
• New epidermal cells push upward from the
stratum basale in each successive layer,
die, become keratinized, and eventually
desquamate (fall off)
• Mitosis of basal cells to surfacing takes
approx. 35 days
• Abrasion speeds up this process and will
make an abnormally thick stratum
corneum (calluses)
Dermal-Epidermal Junction
• Specialized area between the epidermis
and dermis composed mostly of
“basement membrane”
• Includes specialized fibrous elements and
a polysaccharide gel that cement the
epidermis to the dermis
Dermis
1. second layer of the skin (corium or “true skin”)
2. Contains connective (areolar and vessels), muscle, and
nerve tissues, hair follicles, and glands
3. Blood vessels in the dermis expand and contract to help
control body temperature
4. Protects against injury (mechanical strength) and
provides a storage area for water and electrolytes and
houses the somatic receptors (nerves) for the skin
5. contains collagen, elastin, and reticular fibers
a. collagen prevents skin from overstretching and
tearing when a person moves
b. elastin allows skin to stretch as a person moves
6. Four times thicker than the epidermis
Dermis
2 Dermal Cell layers: Papillary layer
1. thin layer that contains blood vessels that provide
nutrients to the epidermis
2. Contains bumps called dermal papillae that project into
the epidermis
3. Made of loose connective (areolar) tissue and a fine
network of thin collagenous and elastic fibers
4. The thin epidermis conforms tightly to the ridges of the
epidermal papillae: gives you your fingerprints and
allows grip of surfaces with feet and grasp and use of
tools
Dermis
2 Dermal Cell Layers: Reticular layer
1. Very dense network of collagenous and
elastic fibers (dense reticulum)
2. Commercially processed from animal
skin as leather
3. Point of attachment for many smooth and
skeletal muscles
4. Contains oil glands, fat cells, sweat
glands and larger blood vessels
Hypodermis/Subcutaneous Layer
1. Adipose layer - fatty layer that aids in insulating and
cushioning the body (not part of skin itself) Also serves
as an energy reserve
a. Separates the dermis from the underlying structures
such as bone and deep fascia (thin membrane that
surrounds muscles)
b. Important because it permits movement of the skin
without tearing and binds skin to tissues below
c. carries the major blood vessels and nerves to the skin
above
d. contains fibroblasts that produce collagen for the
dermis
2. Pacinian corpuscles – larger nerve endings in the skin,
responsible for sensitivity to deep pressure touch and
high frequency vibration.
Skin Color
A. Pigments
1. Melanin
a. produced in epidermis by melanosomes which are housed in
melanocytes deposit melanin in cells of epidermis
b. same number of melanocytes in everyone, but differing
amounts of pigment produced
c. results vary from yellow to tan to black color
d. UV in sunlight increases melanin production
e. melanin production controlled by enzyme tyrosinase (without is
albinism)
2. Carotene
a. yellow-orange pigment (precursor of vitamin A)
b. found in stratum corneum & dermis
3. Hemoglobin
a. red, oxygen-carrying pigment in blood cells
b. if other pigments are not present, epidermis is translucent so
pinkness will be evident (albinism)
Functions of Skin
A. Protection
1. Surface film - This system is really the body’s armor from the external environment
as well as the mechanism from which your body receives information about that
environment.
B. Sensation (receptors)
C. Movement without injury
D. Excretion (sweat and oil)
E. Vitamin D (steroid hormone) production (endocrine function)
1. Skin uses the sun to initiate the vitamin D synthesis process that bones need in
order to develop new bone cells.
2. Skin contains a molecule that’s converted to vitamin D when exposed to the
ultraviolet rays of the sun (7-dehydrocholesterol)
3. Vitamin D moves from the skin into the bloodstream and into the kidney and liver,
where it is converted into a hormone called calcitriol
4. Calcitriol enters the bloodstream and regulates calcium and phosphorus levels in
blood
5. Calcium and phosphorus are key to the development and maintenance of healthy
bones
Functions of Skin cont.
F. Immunity
G. Healing Wounds
1. Skin has the power to regenerate
2. With superficial wounds, the epidermis replaces the damaged cells
(pushes up layer below) and the wound is repaired in just a few days
3. Wounds that damage blood vessel take more time to heal
a. First the skin bleeds. Blood washes away debris and
bacteria away from the wound
b. Blood vessels around the wound constrict to reduce the blood flow
to that area to ensure the body doesn’t loose too much blood
c. Platelets begin to clot in an effort to stop the bleeding
d. As the clot dries out a scab is formed
e. Large amounts of new skin cells are produced in the stratum basale
and make their way to the surface to heal the wound under the scab
Functions of Skin cont.
H. Homeostasis of body temperature
Heat production (When skin is cold)
1.
Sweat glands NOT activated
2.
Blood vessels constrict
(Vasoconstriction)
-
Normal Body Temp 98.6°F (can fluctuate 97-100°F)
Heat Loss (When skin is hot)
1. Sweat glands ARE activated
2. Blood vessels dialate
(Vasodilation)
Homeostatic regulation of heat loss
Appendages of the Skin
Hair
•
•
Protects your body and retains heat, decreases sunburn, eyelashes
protect eyes
Hair fiber (also called pili)
–
–
•
consists of:
»
Shaft: extends above the skin’s surface and a root
»
Hair follicle: Mass of epidermis that extends down in to the dermis and forms a small
tube.
»
Root of the hair (hidden in follicle): lies within the follicle and has an inner epithelial
and outer dermal sheath surrounding it
»
Hair bulb: contains connective tissues, blood vessel, nerves, and germinal matrix
cells that make hair grow through mitosis. Cells become keratinized on surface
»
Sebaceous gland: lubricates hair
»
Erector pili muscle: contracts to move hair
Hair grows from the root outward
Hair color
- Result of melanin produced in melanocytes in hair bulb
- Dark hair contains true melanin
- Blond and red hair contain melanin with iron and sulfur added
- Graying hair is result of decline in melanin production
- White hair has air bubbles in the medullary shaft (no melanin)
Appendages of the Skin
Nails
•
Plates located at the end of the fingers and toes
• Protect the tips of these extremities
• Made of keratin
• Form from the growth of the epidermis
• Sit on top of a nail bed that is supplied with blood vessels
• Start growing near the nail root, and move out over the nail bed as
they grow
• Lunula: Area of cell growth (white semicircle at base of nail)
• Cuticle: Area of the skin that covers the nail at the bottom
Onycholysis – nail separated from nail bed
Appendages of the Skin
Glands
Sweat glands (originate in hypodermis)
a. produce sweat
b. sweat is a watery substance that allows the body to remove excess salt and some waste
products excreted by the kidneys
c. sweat glands also help regulate
body temperature
d. two types
1. Eccrine sweat glands - clear secretion
produced is termed sweat
2. Apocrine sweat glands – produce
a viscous, cloudy, and potentially
odorous secretion that contains
pheromones
3. Ceruminous Glands: ear
Sebaceous glands (originate in dermis)
a. secrete sebum into hair follicles
b. help keep the hair and skin soft
c. waterproofs hair and skin
Blisters
• Form when the skin has
been damaged by friction
or rubbing, heat, cold or
chemical exposure.
• Fluid collects between the
epidermis and the layers
below to cushion the tissue
underneath, protecting it from
further damage and allowing it to heal.
Burns
Degree of Burn
First degree
a. most shallow / superficial
b. effect only top layer of skin (epidermis)
Second degree
a. extend into middle skin layer (dermis)
Third degree
a. involves all three layers of skin
(epidermis, dermis, adipose layer)
b. destroys sweat glands, hair follicles,
and nerve endings
Estimating the Extent of a Burn
Adults
Rule of Nines: divides
almost all of the body into
sections of 9% or of 2 times
9% (18%).
Children
Doctors use charts that
adjust these percentages
according to the child's age
(Lund-Browder charts).
Adjustment is needed
because different areas of
the body grow at different
rates.
Skin Disorders
• Dermatosis
– Skin infections
• Impetigo – common skin infection caused by Staph
or Strep
• Tinea – ringworm, jock itch, athlete’s foot
• Warts
• Boils
•
Skin
Disorders
Vascular and inflammatory skin disorders
– Decubitus ulcers (bedsores)
– Urticaria (hives)
– Scleroderma - chronic autoimmune disease characterized by
fibrosis (or hardening), vascular alterations, and autoantibodies
– Psoriasis
Skin Disorders
– Eczema (Dermatitis)
– Inflammation of the skin that causes it to become swollen, red
and itchy.
– Contact with an allergen or irritant, such as poison ivy
» Dry skin
» Varicose veins
» Health conditions
» Genetic factors
» Physical and mental stress
– Not life-threatening or contagious
– Usually treated with over-the-counter medications
– Prescription medication may be required to ease the symptoms
– Dermatitis can be prevented, depending on the type, by simply
avoiding substances that may cause it.
Skin Disorders
Acne
– Result of clogged sebaceous follicles – a condition that worsens with the
hormonal changes of puberty
– Non life threatening
– Commonly occurs on the face, neck, chest, back, shoulders, scalp, and upper
arms and legs
– Caused by:
• Hormones that stimulate sebaceous (oil-producing) glands
• Clogged pores from the abnormal shedding of skin cells
• Bacterial build-up in the sebaceous glands
– Most acne outbreaks can be treated with over-the-counter medications
– Severe cases may require prescription medication
– Prevention:
•
•
•
•
Avoid using oils, greasy moisturizers and cleansing creams, and other cosmetics
Wash hands before applying makeup
Use an ordinary mild soap and keep skin clean
Keep hands away from your face
Skin Disorders
•
Liver Spots
– A flat patch or area of skin color change
– Light brown to black
– On the hands, arms, or forehead
– Painless
– occur in older skin
– The increased color may be brought on .
by aging, exposure to the sun or other
forms of ultraviolet light, or other unknown
causes
Skin Cancer
• Overgrowth of cells
• Most common cause of skin cancer is the
chronic exposure to the sun or other
ultraviolet light
• Three types of skin cancer
– Basal Cell Carcinoma
– Squamos Cell Carcinoma
– Malignant Melanoma
Basal Cell Carcinoma
• most common form of skin
cancer
• signs for this type of cancer
include
- pale marks
- reddish patches that
recur
- round smooth
growths
with raised
edges
- shiny bumps
- sores that don’t heal
Multiple Basal cell cancer due to x-ray therapy for acne
Squamous cell carcinoma
•
Second most common form of
skin cancer
•
More likely to spread to
surrounding organs than basal cell,
however, this type of cancer is still
fairly treatable
•
Causes and signs of this type of
cancer are the same for basal cell
•
People who have fair skin, light
hair, and blue, green, or grey eyes
are at highest risk for acquiring this
type of cancer
Malignant Melanoma
•Most serious and dangerous type
of skin cancer
•if diagnosed and removed while it
is still thin and limited to the
outermost skin layer, it is almost
100% curable
•Once the cancer advances and
spreads to other parts of the body,
it is hard to treat and can be
deadly
•majority of melanomas are black
or brown and its borders are
irregular and often look like moles
•melanoma spots, unlike moles
often itch or hurt and the skin
around the spot can turn red,
white or grey.
Melanoma of the liver - MRI scan
Skin cancer, raised multi-color melanoma
Skin cancer, melanoma - flat, brown lesion
Skin cancer, melanoma - raised, dark lesion
Skin cancer, melanoma on the fingernail
Skin cancer, close-up of level III melanoma
Skin cancer, close-up of level IV melanoma
Skin cancer, melanoma superficial spreading
Cancer Treatment
• Skin Grafts
– New skin can not regenerate if stratum basale and its
stem cells are destroyed
– Skin graft is covering of wound with piece of healthy
skin
• autograft from self
• isograft from twin
• autologous skin - transplantation of patients skin grown in
culture
• Surgery
• Chemotherapy
• Radiation therapy
Skin Cancer Prevention
• Reduce your risk by protecting your skin
from the damaging rays of the sun
• limit exposure to the sun
• stay away from allergens and other
irritants
• take good care of your skin! It is your
body’s first line of defense against the
outside elements.