Transcript Integumentary System

Integumentary
System
A&P
Charles C. Cook, MD
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Integumentary System
• Integument: An outer protective covering
such as the skin.
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Integumentary System
• The skin together with certain accessory
organs
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MEMBRANE
• Thin sheet-like
structure
• Covers & protects
body surfaces
• Lines cavities
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Membranes
• Lines the internal surfaces of hollow
organs i.e. mouth, lungs, bladder
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4 MAJOR TYPES
OF
MEMBRANES
(see page 109)
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 SEROUS
 MUCOUS
 CUTANEOUS
 SYNOVIAL
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 Serous
Membranes
 Line
cavities that lack
openings to outside
 Secrete serous fluid
 Two classifications
–parietal
–visceral
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• When you hear parietal think wall or the
surroundings.
• When you hear visceral think guts or
organs.
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 Parietal
Membrane
 Lines the walls of
cavities (examples:
parietal pleura,
parietal peritoneum)
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 Visceral
Membrane
 Covers surface of organs
(ex. visceral pleura,
visceral peritoneum)
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Visceral & Parietal Membranes
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Mucous
Membranes
–Line cavities and tubes
that open to the outside
of the body.
–Respiratory, GI,
Urinary and Reprod.
–Goblet cells secrete
mucus
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 Cutaneous
Membrane
–External body covering
(skin)
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 Synovial
Membrane
– Lines joint cavities of
movable joints
– Synovial fluid
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Skin and It’s
Tissues
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Skin
 Composed
of
epithelium, connective
tissue; together
w/certain accessory
organs (glands, hair,
nails & special
receptors)
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INTEGUMENTARY SYSTEM
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Function of the Skin
 Protection
 Body
temp. regulation
 Water loss reduction
 Houses sensory receptors
 Vitamin D synthesis
 Excretion
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Protection
• Protects underlying tissue
– Keratinization i.e. callus
• Bacterial/Antigen invasion
– Acidic pH
– Naturally occurring antibiotic
– Langerhan’s cells—activate immune sys.
– Macrophages
• Ultraviolet radiation
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Body temperature regulation
• Radiation – thermal energy moving from
warmer to cooler environment.
• Conduction – objects in contact with one
another transferring heat from warmer to
cooler environment.
• Convection – warm air rises and cool air
falls.
• Evaporation – sweat absorbs heat from
body then heat lost in evaporation.
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Body temperature regulation
• Vasodilation—blood vessels increase in
diameter
• Vasoconstriction—blood vessels
decrease in diameter
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Body temperature regulation
• Body temperature too high
– Vasodilation
– Increase sweating
• Body temperature too low
– Vasoconstriction
– Decreased sweating
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Water Loss Reduction
• Average water loss due to sweat is 300500 ml/day (depends on environment and
activity level)
• Stratum corneum provides barrier against
excessive water loss
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Houses Sensory
Receptors
• Sensory nerve endings that detect stimuli related
to temperature, touch, pressure and pain
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Vitamin D Synthesis
• Vitamin D needed to absorb calcium in the
gut.
• Modified cholesterol molecules in the skin
are activated by UV light and form Vitamin
D.
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Excretion
• Sweat
– Primarily water
– Small amounts of urea, uric acid, ammonia
– pH is acidic—Why?
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 The
skin is composed of 3
distinct layers:*
– Epidermis
– Dermis
– Subcutaneous (hypodermis
or SubQ)
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 Epidermis-
Outer layer
–protective function:
water
loss
mechanical injury
harmful chemicals
harmful microorganisms
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Epidermis
 The
epidermis is
composed of stratified
squamous epithelial
tissue
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Epidermis
 Outermost
layer dead cells,
innermost living
 Lacks blood vessels
 Remember this for nails
and hair
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Stratum Basale
 The
deepest layer contains
cells undergoing mitosis
–nourished by dermal blood
vessels
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Stratum Corneum
• Outermost layer of the epidermis
• Epidermal cells that have undergone
keratinization
• Skin cells migrate toward the surface
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 During
keratinization the
cytoplasm develops tough,
fibrous, waterproof protein
called keratin and the cells
die (2-4 wks)
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Melanocytes
 Produce
melanin (all
humans have about the
same number of
melanocytes, regardless of
racial origin)
 Protection from U.V. light
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Melanocytes
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 Skin
color
– largely due to melanin and
size of the pigment granules
– environ., physiological, and
genetic factors
– Oxygen depleted blood,
darker color and gives off a
bluish hue (cyanosis)
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Dermis- Thick Inner layer
 Fibrous
connective tissue
 Living throughout
 Blood vessels nourish and
regulate temp.
 Nerve fibers scattered
throughout the dermis
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Dermis
Contained in the dermis
1. Nerves
2. Hair follicles
3. Sweat glands
4. Sebaceous glands
5. Blood vessels
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Subcutaneous
Layer
(hypodermis)*
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 Loose
connective tissue,
adipose tissue
 Conserves heat, stores
energy
 Blood vessels supply
adipose tissue
 Resist heat exchange
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ACCESSORY ORGANS
•
•
•
•
Hair
Nails
Oil glands
Sweat glands
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Hair
• All body surfaces except
palms, soles,lips, nipples,
and some of the external
repro. organs
• Dead epidermal cells
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 Develops
from epidermal
cells at base of hair follicle
 Older cells pushed to the
surface, keratinize and die
 Visible portion is called
the shaft
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 Arrector
pili muscle
contracts to straighten
and raise hair
 Hair color is
determined by genetics
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When Hair Goes Bad
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Nails
-
rigid plates covering
tips of digits
– produced by epidermal
cells that undergo
keratinization
– harder than the keratin
produced in the rest of
the skin
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Sebaceous Glands
 Generally
associated with
hair follicles
 Secrete sebum, keeping
skin and hair soft and
pliable
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 Sebum
composed of fatty
material and cellular
debris
 No sebaceous glands in
palms or soles
– responsible for acne
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Sweat (sudoriferous) glands
– consist of a coiled tube
– primarily water, but contains
salt and waste
– two types: apocrine and
eccrine
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 Apocrine
glands
–respond to emotional
stress
–begin to function at
puberty
–located in the groin
and armpits
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 Eccrine
sweat glands
– respond to elevated body
temperature
– environmental heat or
exercise
 NOTE:
Hair follicles and
Sweat glands are lined
w/epidermal cells
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Free Nerve Endings
• Common in epithelial tissues
• Distal part of the neuron
• Sensitive to tissue damage and pressure
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Meissner’s Corpuscles
• Masses of connective tissue cells
• Abundant in the hairless portions of the
skin
– Lips, palms, soles, external genitalia and
nipples
• Responds to light touch
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Pacinian Corpuscles
• Relatively large structures
• Composed of connective tissue fibers and
cells
• In the deeper dermis and subcutaneous
tissues, tendons and ligaments
• Respond to heavy pressure and
associated with the sensation of deep
pressure
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 Body
Temperature
Regulation
– Temp. above normal,
blood vessels dilate,
sudoriferous glands
secrete
– Temp. below normal,
blood vessels constrict,
inactivity
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– Excessive heat loss causes
skeletal muscles to
contract involuntarily
(shivering)**
– Circulatory and
respiratory systems also
help to control body
temperature.
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Langer’s Lines
• Tension lines in the skin
• Incisions made along these lines are
under less tension when closed and
therefore heal with better scar results
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Wound Healing
• Shallow wound – epithelial cells
at the margin of the wound
reproduce more rapidly to fill the
gap.
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Wound Healing
• Wound extends into dermis or sub-q
– Escaping blood forms clot
– Fibroblasts migrate into area
– Phagocytic cells engulf dead cells and debris
– Damaged tissue is replaced and scab falls off
• Large open wounds –granulations form
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Wound Closure
• If edges can be approximated better end
results occur (less infiltration of fibroblasts)
• Only clean wounds should be closed
(primary intention)
• Dirty wounds should be debrided and
irrigated with copious amounts of saline
and possibly left open for 2-3 days
(delayed closure)
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Wound Closure
• Bite wounds (especially human and cat
bites) should not be closed primarily
• Severely contaminated wounds (blast
wounds, perforated viscous, etc.) are often
left open to granulate in (secondary
intention)
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NOW WHAT WAS
HE TALKING
ABOUT AGAIN?!?!?
QUESTIONS??
80
Question
• List the protective properties of the skin.
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Answer
•
•
•
•
•
•
Protection
Body temp reg.
Water loss reduction
Houses sensory receptors
Vitamin D synthesis
Excretion
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Question
• Sudoriferous gland is another name for
what?
84
Answer
• A sweat gland.
85
Question
• If all races have approximately the same
number of melanocytes, what accounts for
the difference in skin color?
86
Answer
• Although all races have approximately the
same number of melanocytes the amount
of the pigment melanin in each
melanocyte varies.
87
Question
• True or false
• The mammary gland is a type of sweat
gland.
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Answer
• True The mammary gland is a modified
sweat gland that belongs to the
integumentary system although it is
frequently grouped with the reproductive
system.
89
Question
• The epidermis contains both _________
and ___________ cells.
90
Answer
• Living and non-living
91
Question
• In what layer of the skin will you find hair
follicles, sweat glands and sebaceous
glands?
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Answer
• Dermis
93
Question
• Describe how the skin regulates body
temperature.
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Answer
• Excess heat- vasodilatation and sweat
production.
• Body temperature low – vasoconstriction
to keep core warmer, sweat glands
become inactive
• Excessive heat loss or hypothalamus
dysfunction – shivering occurs
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Question
• Apocrine sweat glands respond to ______
________ while eccrine sweat glands
respond to _________ ______ ________.
96
Answer
• Emotional stress; elevated body
temperature
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Question
• What do epidermal skin development, nail
growth and hair growth have in common?
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Answer
• Epidermal cells develop deeper where
they are closer to nutrients; they slowly
migrate to the surface slowly dying and
becoming more compacted; they undergo
keratinization and become skin, nails or
hair.
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