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Skin and Integumentary System
“A covering for everything and
everything under its cover”
I. Classification of Body Membranes
A. membrane - a thin, sheet-like structure that has an
important function
Ex. cover and protect body surfaces
line the body cavities
cover the inner surfaces of hollow organs
secrete lubricating fluids to reduce friction
B. There are two main types of body membranes:
1. epithelial membranes - made up of epithelial tissue and an
underlying layer of connective tissue
2. connective tissue membranes - composed entirely of
different types of connective tissue
C. There are three types of epithelial tissue membranes:
cutaneous membranes,serous membranes, mucous membranes
1. The cutaneous membrane is the skin. It is one of the
largest organs; composes 16% of the body weight.
2. Serous membranes line body cavities and cover the
surface of internal organs.
a. It is one continuous membrane that lines each of the body
cavities.
1. There is a pleural membrane that lines the
thoracic cavity and covers the organs in the t
thorax.
2. There is a peritoneal membrane that lines the
abdominal cavity and covers the organs in the
abdomen.
b. The part of a serous membrane that lines the body
cavity is known as the parietal portion.
c. The portion of the membrane that covers
the internal organs is known as the visceral portion.
d. The suffix “itis” means inflammation. What do
you think the terms “peritonitis” and “pleuritis”
mean?
3. Mucous membranes are epithelial membranes that line
body surfaces that open to the outside.
a. Ex. membranes lining the respiratory, the
digestive, the urinary, and the reproductive tracts.
b. The epithelial cells secrete a thick , slimy
material known as mucus that keeps the
membrane moist and soft.
D. Connective tissue membranes lack epithelial tissue.
1. One type lines the body’s joints.
a. They are called synovial membranes.
b. They are smooth and slick and secrete a thick
lubricating fluid called synovial fluid.
c. Synovial membranes line the small cushionlike sacs that are found between many of the
body’s moving parts; these sacs are
called bursae. (What would the term bursitis
mean?)
II. Skin
A. The skin is called a cutaneous membrane.
1. The skin consists of two layers: the epidermis
and the dermis.
2. The epidermis is the outermost layer and
consists of stratified squamous epithelium.
a. The epidermis is made of many layers of
cells
1) stratum basale or germinativum the innermost layer undergoes mitosis
produces new skin cells that allows the
skin to repair itself .
gives color to the skin contains
melanocytes that produce melanin
2) Stratum spinosum – daughter cells
3) Stratum granulosum – Cells becoming flatter as they
rise to the surface, filling with keratin begins
4)Stratum lucidium – only on hairless and thick parts of
the body palms and soles of feet
5) stratum corneum - the outer layer of skin with cells
filled with keratin – (a tough, water proof
material these cells are dead and are shed from
the skin)
3. The dermis is the deeper layer and is composed mainly of
connective tissue.
a. contains many collagen fibers that strengthen the skin
and allow it to be flexible and elastic
b. upper layers contain peg-like projections called
dermal papillae that form the ridges and grooves that form
our finger prints
c. contains nerves and nerve endings that provide
sensory information
d. contains muscle fibers, sweat and oil glands, blood
vessels and hair follicles
4. The skin is supported by a thick layer of fat and connective
tissue called the subcutaneous tissue.
B. Skin Appendages
1. hair covers the human body
a. grows from hair follicles in the dermis
b. hair shaft is the visible part of the hair; the hair
root is the hidden part of the hair
c. arrector pili muscle - cause the hair to “stand
on end” and cause “goose pimples”
d. lanugo - the fine and soft hair that covers
much of the body in newborn infants
2. receptors provide sensory information - touch, pain,
temperature, and pressure
a. pacinian corpuscle - detects pressure on the skin
b. Meissner’s corpuscle - detects light touch
c. free nerve endings detect pain
d. Krause’s end bulbs detect cold
e. other receptors detect heat, crude touch, and
vibrations
3. nails are composed of keratin and become hard and platelike
a. cover the ends of the toes and fingers
b. nail body is the visible part of the nail
c. nail root lies hidden in the nail cuticle
d. lunula - white crescent shaped area closest to the
cuticle
e. nail bed - layer of epithelium under the nail
4. skin glands
a. two types of glands –
sudoriferous -sweat glands
sebaceous glands
b. sweat glands - two types
i. eccrine glands most numerous produce prespiration
pores - openings through sweat is
released1 square inch of skin has 3000
sweat glands
ii. apocrine glandsin the armpit and genital area produce a
thick, milky secretion skin bacteria
breakdown the secretion and produce a
strong odor
c. sebaceous glands –
i. grow where hair grows
ii. their secretion is called sebum - lubricates the hair and
skin prevents drying and cracking of the skin
iii. increases during adolescence - causes pimples
sebum can darken and form blackheads
C. Functions of the skin
1. Protection - “Our first line of defense”
a. The tough keratin filled cells protect against the
entry of harmful bacteria and chemicals
b. The tough cells resist tears and cuts.
c. The skin is water tight and protects a
against water loss
d. The melanin protects against UV rays.
2. Temperature regulation
a. The skin regulates temperature by regulating
the flow of sweat and the flow of blood near the
surface.
b. Evaporation of sweat cools the body.
Vasodilation - Increased blood flow causes
heat loss by radiation.
Vasoconstriction – conserves heat by
restricting the flow of blood
3. Sense Organ Activity (nerves) – interacting with the
environment to help us respond appropriately
D. Burns
1. Burns can be caused by fire, contact with a hot
surface, over exposure to UV radiation, electricity, or a
chemical
2. Recovery from burns depends on the severity of the
burn and the total area of skin involved.
3. Rule of nines - rule to estimate the extent of a burn
a. The body is divided into 11 areas that are about
9% of the surface area.
b. See the chart on page 125
4. Classification of burns
a. first degree burns - involves the superficial layers
minor discomfort and reddening
no blistering
superficial layers may peal
b. second degree burns - involves the deep epidermal layers
damages the sweat glands and hair
follicles
blisters occur
causes severe pain, swelling and
fluid loss
scarring is common
c. third degree burns -
complete destruction of epidermis
and dermis
tissue death often extends into the
subcutaneous area
damage often involves the
underlying muscle and bone
usually little or no pain immediately
after the injury due to nerve injury
fluid loss is severe
III. Skin Cancer
A. Most skin tumors are benign, but there are some that are
cancerous.
B. The most important risk factor for the development of skin
cancer is exposure to sunlight (UV rays). Frequent exposure
to chemicals, irritation, and infection also seem to be risk
factors.
C. There are three types of skin cancer: basal cell carinoma,
squamous cell carcinoma, and malignant melanoma.
D. Basal Cell Carcinoma - the least cancerous of the skin
cancers. The cancer is slow growing and slow to
metastasize. They occur most often on sun exposed areas of
the face or head. The lesions appear as nodules that become
ulcerated. This cancer is usually curable.
E. Squamous Cell Carcinoma - grows rapidly and spreads if
not treated. Seems to be related to sun exposure. Found most
often on the scalp, ears, nose, dorsum of the hands and lower
lip. The growth starts as a scaley, reddened bump that forms a
shallow ulcer.
F. Malignant Melanoma - a cancer of the melanocytes. It is
the most aggressive of the skin cancers. It grows rapidly and
metastasizes early. It can occur anywhere there is pigment;
sometimes develops from moles. It usually appears as a
spreading brown to black patch on the skin. American Cancer
Society suggests using the ABCD rule for recognizing
malignant melanoma:
A = asymmetry - the two sides of the spot or mole do
not match.
B = border irregularity - the borders of the spot or mole
are not smooth, but have indentations.
C = color - the spot or mole contains areas of different
colors (blacks, browns, tans, and maybe reds and blues)
D = diameter - the spot is larger than 6 mm in diameter
(the size of a pencil eraser)
Whenever you notice an odd
mole or spot on your body it is
always important to check for it.
Here are some easy ways you
can remember what to look for!
By: Becky Walls
A= Asymmetry
If you draw a line through this
mole, the two halves will not
match.
B= Border Irregularity
When the Borders of the lesion
are not smooth but exhibit
indentations. The edges may be
scalloped or notched.
C= Color
When the pigmented spot contains areas
of different colors. (Blacks, browns, reds,
tans, blues)
D= Diameter
If the spot is any larger
than 6mm in diameter.
E= Evolving
Any change — in size, shape, color,
elevation, or another trait, or any
new symptom such as bleeding,
itching or crusting — points to
danger.
Birthmarks
Birthmarks range from hardly noticeable to disfiguring.
The two main types of birthmarks
1. red, vascular birthmarks - happen when blood vessels don't form
correctly — either there are too many of them or they're wider than
usual. .
2. pigmented birthmarks - caused by an overgrowth of the cells that
create pigment in skin.
Nearly all are harmless, but it is important to talk to the doctor for the
few occasions when it is not harmless.
Vascular Birthmarks
Macular Stains – appear
darker as a child cries
Hemangioma
“Strawberries”, “Angel
Kisses”, “Stork bites”
Disappear at about 9yrs
Port Wine Stains need
treatment as they continue
to grow throughout life
Pigmented Birthmarks
Café Au Lait marks look
like coffee with milk, one is
OK but more than one
needs to be checked for and
nerve disorder
Mongolian spots – grey
blue patches usually on the
lower body. Disappear by
school age
Moles – also called Nevus,
Can have various skin
colors, be flat or raised.
Can be present at birth or
come later. Only very large
or changing moles need to
be checked for melanoma
throughout life.