Transcript Document

Integumentary System
Skin (integument) is the principal organ.
 Appendages – hair, nails, and skin glands
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Body Membranes
Epithelial – epithelial tissue and an
underlying layer of specialized connective
tissue
 Connective – exclusively various types of
connective tissue
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Epithelial Membranes
1. Cutaneous – skin
2. Serous – only on surfaces of closed
cavities
A. Parietal – lines wall of a body cavity
B. Visceral – covers the surface of organs
in the body cavity
3. Mucous – line body surfaces opening directly to
exterior, produce mucus (soft, moist)
Serous Membranes
Thoracic Cavity – pleura
 Abdominal Cavity – peritoneum
 Pleurisy – inflammation of the serous
membranes that line the chest cavity and
lungs
 Peritonitis – inflammation of the serous
membranes in the abdominal cavity that line
the walls and cover the abdominal organs
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Connective Tissue Membranes
Do not contain epithelial components
 Synovial membranes – lines spaces between
bones and joints; secret a thick and colorless
lubricating fluid called synovial fluid
 Line small, cushion like sacs called bursae
found between moving body parts
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Activity
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Differentiate a cutaneous membrane from a serous
membrane.
There are two types of serous membranes, parietal
and visceral. What is the difference?
Name the serous membranes in the thoracic cavity.
Name the serous membranes in the abdominal
cavity.
Answers
Cutaneous-skin, Serous-on surfaces only in
enclosed cavities
 Parietal lines the walls of a body cavity,
visceral covers the surface of organs in the
body cavity
 Parietal and visceral pleura
 Parietal and visceral peritoneum
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Structure of the Skin
Epidermis – outermost layer, stratified
squamous epithelium
 Dermis – deeper layer, largely connective
tissue
 Hypodermis-subcutaneous tissue, loose
layer of connective tissue and fat,
insulation, stored energy and food source,
protection, shock-absorbing pad
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Epidermis
Stratum germinativum – innermost layer,
undergo mitosis and reproduce themselves
 As new cells approach the surface, the
cytoplasm is replaced with keratin
 Keratin – tough, waterproof material that
provides cells of the outer layer with an
abrasion-resistant, protective quality
 Stratum corneum – tough outer layer, where
dry, dead cells “flake off”

The deepest cell layer of the epidermis
produces a special pigment that gives color
to the skin.
 Melanin – brown pigment produced by
specialized cells called melanocytes
 Cyanosis – skin turns bluish-gray color
 Blisters – caused by breakdown of union
between cells or primary layers of the skin
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Activity
Differentiate the dermis and epidermis.
 What is keratin?
 What is the stratum corneum?
 What are melanocytes?
 What causes blisters?
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Dermis
Cells scattered apart with many fibers in
between
 Collagen or white fibers – tough and strong
 Elastic or yellow fibers – stretchable, elastic
 Dermal papillae – parallel rows of peg-like
projections, helps bind skin layers together
and forms ridges and grooves for
fingerprints (develop before birth)
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Deeper areas of dermis are filled with a
dense network of tough collagenous and
stretchable elastic fibers
 Number of elastic fibers decreases with age
(wrinkles)
 Dermis also contains nerve endings, muscle
fibers, hair follicles, sweat and sebaceous
glands, and many blood vessels
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Appendages of the Skin
Lanugo – soft hair of fetus and newborn
 Hair growth begins when cells of the
epidermal layer of the skin grow down into
the dermis, forming a hair follicle
 Hair growth begins from a small, cupshaped cluster of cells called the hair papilla
 The hair papilla (nourished by blood vessel)
is located in the hair bulb at the base of the
follicle
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Root – part of hair that lies hidden in the
follicle
 Shaft – visible part of hair, extends from
follicle
 New hair will grow as long as cells in the
papilla of the hair follicle remain alive
 Alopecia – hair loss of any kind
 Arrector pili – involuntary smooth muscle
that causes hair to stand up (goose pimples)
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Receptors
Free nerve endings – respond to pain and
changes in temperature
 Meissner’s (tactile) corpuscle – capable of
detecting light touch
 Pacinian corpuscle – capable of detecting
pressure
 Krause’s end bulbs – detect sensations of
touch and low frequency vibrations
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Nails
Produced by epithelial cells over terminal
ends of fingers and toes
 Nail body – visible part of nail
 Cuticle – fold of skin
 Root – hidden by cuticle
 Lunula – crescent-shaped area nearest root
 Nail bed – contains blood vessels, changes
color with change in blood flow
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Skin Glands
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Two types
1. Sweat or sudoriferous
A. Eccrine– most numerous,
perspiration through pores on skin
surface, body heat regulation
B. Apocrine – axilla and genitalia, thick
and milky secretion, breakdown of
secretion by bacteria causes odor
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2. Sebaceous – oil, grows where hair grows
Secretes oil or sebum for hair and
skin
More secretion during adolescence
Regulated by sex hormones
Sebum in ducts may darken to form
blackhead
Acne vulgaris – inflammation of
sebaceous gland ducts
Think!
Draw a square inch box to represent a
square inch of skin tissue.
 List some of the structures that fit into one
square inch of skin.
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Answers
500 Sweat glands
 Over 1,000 nerve endings
 Yards of tiny blood vessels
 100 oil or sebaceous glands
 150 sensors for heat (hot and cold)
 Millions of cells
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Dermatoses: Disorders of the Skin
1. Elevated skin lesions
a. Papule – small, firm
b. Plaque – large, raised
c. Vesicle – blister
d. Pustule – pus-filled
e. Crust – scab
f. Wheal - hive
2. Flat skin lesions
a. Macule – flat, discolored
3. Depressed lesions
a. Excoriation - scratch
b. Ulcer – crater like
c. Fissure – deep crack or break
Burns
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Rule of Nines – See page 167
First-degree: only surface layers of epidermis
involved, no blistering
Second-degree: involve deep epidermal layers
and always cause injury to upper layers of
dermis; blistering, swelling, severe pain, fluid
loss
Note: Deep second-degree burns damage sweat
glands, hair follicles, and sebaceous glands.
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Third-degree or full-thickness burns (fourth
degree): complete destruction of epidermis
and dermis, nerve endings destroyed
Third-degree burns often involve bone and
muscle (full-thickness). The lesions are
insensitive to pain immediately after injury
because of the destruction of nerve endings.
Intense pain is soon experienced; the fluid
loss is serious problem.
Skin Infections
Impetigo – highly contagious
staphylococcal infection
 Tinea – fungal infection
 Warts – benign neoplasms caused by
papillomavirus
 Boils – furuncles; staphylococcal infection
in hair follicles
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Vascular and Inflammatory Skin
Disorders
Decubitus ulcers – bedsores; pressure slows
down blood flow
 Urticaria – hives; fluid loss from blood
vessels
 Scleroderma – disorder of vessels and
connective tissue; hardening of the skin
 Psoriasis – chronic inflammatory condition;
scaly plaques
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Eczema – common inflammatory condition;
papules, vesicles, and crusts; a symptom of
an underlying condition
Skin Cancer
Squamous cell carcinoma – most
common; hard, raised tumors
2. Basal cell carcinoma – papules with a
central crater; rarely spreads
3. Melanoma – most serious; malignancy in
a nevus (mole)
Kaposi sarcoma – purple lesions; AIDS
and other immune deficiencies
Exposure to sunlight – causative factor
1.