Download Skin and Body Membranes

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Prepared by Patty Bostwick-Taylor,
Florence-Darlington Technical College
CHAPTER
4
Skin and
Body
Membranes
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Body Membranes
Function:
• Cover body surfaces
• Line body cavities
• Form protective sheets around organs
Classification:
• Membranes with epithelial tissue
1. Cutaneous membranes
2. Mucous membranes
3. Serous membranes
• Connective tissue only membranes
1. Synovial membranes
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Cutaneous Membrane
Cutaneous membrane = skin
•Dry membrane
•Outermost protective boundary
•Superficial epidermis is composed of
keratinized stratified squamous epithelium
•Underlying dermis is mostly dense
connective tissue
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Cutaneous
membrane
(skin)
(a) Cutaneous membrane (the skin)
covers the body surface.
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Figure 4.1a
Mucous Membranes
• Moist membranes that line all body cavities that
open to the exterior body surface
• Often adapted for absorption or secretion of
mucous
• Mouth & esophagus = surface layer is stratified
squamous epithelium
• Rest of digestive tract = surface layer is simple
columnar epithelium
• Underlying the mucous membrane is loose
connective tissue called lamina propria
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Mucosa of
nasal cavity
Mucosa of
mouth
Esophagus
lining
Mucosa of
lung bronchi
(b) Mucous membranes line body cavities
open to the exterior.
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Figure 4.1b
Serous Membranes
• Line body cavities that are closed to the exterior of
the body
• Surface layer is simple squamous epithelium
• Underlying is a thin layer of areolar connective tissue
• Serous membranes occur in pairs separated by
serous fluid
• Visceral layer covers the outside of the organ
• Parietal layer lines a portion of the wall of ventral
body cavity
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Outer balloon wall
(comparable to parietal serosa)
Air (comparable to serous cavity)
Inner balloon wall
(comparable to visceral serosa)
(d) A fist thrust into a flaccid balloon demonstrates
the relationship between the parietal and visceral
serous membrane layers.
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Figure 4.1d
Serous Membranes
Specific serous membranes:
•Peritoneum
•Abdominal cavity
•Pleura
•Around the lungs
•Pericardium
•Around the heart
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Parietal
pleura
Visceral
pleura
Parietal
peritoneum
Visceral
peritoneum
Parietal
Visceral
pericardium pericardium
(c) Serous membranes line body cavities
closed to the exterior.
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Figure 4.1c
Connective Tissue Membrane
Synovial membrane
•Soft areolar connective tissue
•Lines fibrous capsules surrounding joints
•Secretes a lubricating (synovial) fluid
•Also line bursae and tendon sheaths
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Ligament
Joint cavity
(contains
synovial fluid)
Articular (hyaline)
cartilage
Fibrous
capsule
Synovial
membrane
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Articular
capsule
Figure 4.2
Integumentary System
Skin (cutaneous membrane) and its derivatives:
•Sweat glands
•Oil glands
•Hair
•Nails
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Skin Functions
1. Protects deeper tissues from:
• Mechanical damage (bumps)
• Chemical damage (acids and bases)
• Bacterial damage
• Ultraviolet radiation (sunlight)
• Thermal damage (heat or cold)
• Dessication (drying out)
2. Aids in body heat loss or heat retention as controlled by
the nervous system
3. Aids in excretion of urea and uric acid
4. Synthesizes vitamin D in the presence of UV radiation
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Skin Structure
Epidermis—outer layer
• Stratified squamous epithelium
• Cornified or keratinized (hardened by keratin) to
prevent water loss
• Avascular
• Most cells are keratinocytes
Dermis – inner layer
• Dense fibrous connective tissue
• Blood vessels, nerves, glands, hairs….
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Hair shaft
Dermal papillae
Epidermis
Papillary
layer
Dermis
Pore
Appendages of skin
• Eccrine sweat gland
• Arrector pili muscle
• Sebaceous (oil) gland
• Hair follicle
• Hair root
Reticular
layer
Hypodermis
(superficial fascia)
Nervous structures
• Sensory nerve fiber
• Lamellar corpuscle
• Hair follicle receptor
(root hair plexus)
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Cutaneous vascular plexus
Adipose tissue
Figure 4.3
Skin Structure
Subcutaneous tissue (hypodermis) is deep to
dermis
• Not technically part of the skin
• Anchors skin to underlying organs
• Composed mostly of adipose tissue
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Layers of the Epidermis
From deepest to most superficial:
•Stratum basale (germnativum; basal layer))
•Stratum spinosum (spiny layer)
•Stratum granulosum (granulated layer)
•Stratum lucidum (on soles of feet and palms
of hands - thick, hairless skin only)
•Stratum corneum (cornified layer)
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Keratinocytes
Desmosomes
Epidermal
dendritic cell
Stratum corneum. Cells are dead;
represented only by flat membranous
sacs filled with keratin. Glycolipids in
extracellular space.
Stratum granulosum. Cells are
flattened, organelles are deteriorating;
cytoplasm full of granules.
Stratum spinosum. Cells contain thick
bundles of intermediate filaments
made of pre-keratin.
Merkel
cell
Sensory
Melanocytes Melanin nerve
granules ending
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Stratum basale. Cells are actively
dividing stem cells; some newly
formed cells become part of the more
superficial layers.
Dermis
Figure 4.4
Melanin
•Pigment (melanin) produced by melanocytes
•Melanocytes are mostly in the stratum basale
•Color is yellow to brown to black
•Amount of melanin produced depends upon
genetics and exposure to sunlight
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Dermis
Two layers
1. Papillary layer (upper dermal region)
• Fingerlike projections called dermal papillae
• Some contain capillary loops
• Others house pain receptors and touch
receptors
2. Reticular layer (deepest skin layer)
• Blood vessels
• Sweat and oil glands
• Deep pressure receptors
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Hair shaft
Dermal papillae
Epidermis
Papillary
layer
Dermis
Pore
Appendages of skin
• Eccrine sweat gland
• Arrector pili muscle
• Sebaceous (oil) gland
• Hair follicle
• Hair root
Reticular
layer
Hypodermis
(superficial fascia)
Nervous structures
• Sensory nerve fiber
• Lamellar corpuscle
• Hair follicle receptor
(root hair plexus)
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Cutaneous vascular plexus
Adipose tissue
Figure 4.3
Dermis
Overall dermis structure:
• Collagen and elastic fibers located throughout
the dermis
• Collagen fibers give skin its toughness
• Elastic fibers give skin elasticity
• Blood vessels play a role in body temperature
regulation
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Epidermis
Papillary layer
of dermis
Reticular layer
of dermis
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Figure 4.5
Normal Skin Color Determinants
1. Melanin
• Yellow, brown, or black pigments
2. Carotene
• Orange-yellow pigment from some vegetables
3. Hemoglobin
• Red coloring from blood cells in dermal capillaries
• Oxygen content determines the extent of red
coloring
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Alterations in Skin Color
• Redness (erythema) - due to embarrassment,
inflammation, hypertension, fever, or allergy
• Pallor (blanching) - due to emotional stress such
as fear, anemia, low blood pressure, impaired
blood flow to an area
• Jaundice (yellowing) - liver disorder
• Bruises (purpling) – hematomas
• Decubitus ulcer (bed sore) – skin cells are
deprived of oxygen
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Skin Appendages
1. Cutaneous glands
• Sebaceous glands
• Sweat glands
2. Hair
3. Nails
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Appendages of the Skin
Oil (sebaceous) glands
• Produce oil (sebum)
• Lubricant for skin
• Prevents brittle hair
• Kills bacteria
• Most have ducts that empty into hair follicles;
others open directly onto skin surface
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Sweat
pore
Sebaceous
gland
Eccrine
gland
Dermal connective
tissue
Sebaceous
gland duct
Hair in
hair follicle
Secretory cells
(a) Photomicrograph of a sectioned
sebaceous gland (14×)
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Figure 4.7a
Appendages of the Skin
Sudoriferous (sweat) glands
• Produce sweat
• Widely distributed in skin
• Two types of sudoriferous glands
1. Eccrine
• Open via duct to pore on skin surface
• Produce sweat (clear)
2. Apocrine
• Ducts empty into hair follicles
• Begin to function at puberty
• Release sweat that also contains fatty acids and
proteins (milky/yellowish color)
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Sweat
pore
Eccrine
gland
Sebaceous
gland
Dermal connective
tissue
Eccrine
gland duct
Secretory cells
(b) Photomicrograph of a
sectioned eccrine
gland (180×)
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Figure 4.7b
Sweat and Its Function
Composition
• Mostly water
• Salts and vitamin C
• Some metabolic waste
• Fatty acids and proteins (apocrine only)
Function
• Helps dissipate excess heat
• Excretes waste products
• Acidic nature inhibits bacteria growth
Odor is from associated bacteria
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Appendages of the Skin
Hair
• Produced by the hair follicle
• Consists of hard keratinized epithelial cells
• Melanocytes provide pigment for hair color
• Hair grows in the matrix of the hair bulb in the
stratum basale
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Figure 4.8c
Appendages of the Skin
Hair anatomy
• Central medulla
• Cortex surrounds medulla
• Cuticle on outside of cortex
• Most heavily keratinized
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Cuticle
Cortex
Medulla
(b) Hair
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Figure 4.8b
Hair
shaft
Arrector
pili
Sebaceous
gland
Hair root
Hair bulb
in follicle
(a)
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Figure 4.8a
Appendages of the Skin
•Notice how the scale-like cells of the cuticle
overlap one another in this hair shaft image
(660×)
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© 2012 Pearson Education, Inc.
Figure 4.9
Appendages of the Skin
Nails
• Scale-like modifications of the epidermis
• Heavily keratinized
• Stratum basale extends beneath the nail bed
• Responsible for growth
• Lack of pigment makes them colorless
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Appendages of the Skin
Nail structures
• Free edge
• Body is the visible attached portion
• Root of nail embedded in skin
• Cuticle is the proximal nail fold that projects
onto the nail body
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Lunule
Lateral
nail fold
(a)
Free edge Body Cuticle
Root of nail
of nail
of nail
Proximal Nail
nail fold
matrix
(b)
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Nail bed
Bone of fingertip
Figure 4.10a-b
Skin Homeostatic Imbalances
Burns
• Tissue damage and cell death caused by heat,
electricity, UV radiation, or chemicals
• Immediate danger
• Fluid loss – leading to circulatory shock and
possible kidney shut-down.
• Fluids must be replaced asap
• Later danger
• Infection
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Rule of Nines
How to determine the extent of fluid loss
• Body is divided into 11 areas for quick
estimation
• Each area represents about 9 percent of total
body surface area
“Rule of Nines”
• This allows a rapid estimation of how much
fluid to replace with an I.V.
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Totals
41/2%
Anterior and posterior
head and neck, 9%
Anterior and posterior
upper limbs, 18%
41/2%
41/2%
Anterior and posterior
trunk, 36%
Anterior
trunk, 18%
Perineum, 1%
9%
9%
Anterior and posterior
lower limbs, 36%
100%
(a)
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Figure 4.11a
Severity of Burns
1. First-degree burns
• Only epidermis is damaged
• Skin is red and swollen
2. Second-degree burns
• Epidermis and upper dermis are damaged
• Skin is red with blisters
3. Third-degree burns
• Destroys entire skin layer; burned area is painless
• Burn is gray-white or black
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Figure 4.11b
Critical Burns
Burns are considered critical if
• Over 25 percent of body has second-degree
burns
• Over 10 percent of the body has third-degree
burns
• There are third-degree burns of the face,
hands, or feet
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Skin Homeostatic Imbalances
Infections and allergies
• Athlete’s foot (tinea pedis)
• Caused by fungal infection
• Boils and carbuncles
• Caused by bacterial infection
• Cold sores
• Caused by virus
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Skin Homeostatic Imbalances
• Contact dermatitis
• Exposures cause allergic reaction
• Impetigo
• Caused by bacterial infection
• Psoriasis
• Cause is unknown
• Triggered by trauma, infection, stress
• Decubitis ulcers
• Bed sores
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© 2012 Pearson Education, Inc.
Figure 4.12a-c
Skin Cancer
Cancer - abnormal cell growth resulting in the
formation of masses called tumors.
• Classified two ways
• Benign
• Does not spread (encapsulated)
• Malignant
• Metastasized (moves) to other parts of the
body
• Skin cancer is the most common type of cancer
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Skin Cancer Types
Basal cell carcinoma
• Least malignant
• Most common type
• Arises from stratum
basale
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Skin Cancer Types
Squamous cell carcinoma
• Metastasizes to lymph
nodes if not removed
• Early removal allows a
good chance of cure
• Believed to be suninduced
• Arises from stratum
spinosum
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Skin Cancer Types
Malignant melanoma
• Most deadly of skin
cancers
• Cancer of melanocytes
• Metastasizes rapidly to
lymph and blood
vessels
• Detection uses ABCD
rule
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ABCD Rule – to identify melanoma
• A = Asymmetry
• Two sides of pigmented mole do not match
• B = Border irregularity
• Borders of mole are not smooth
• C = Color
• Different colors in pigmented area
• D = Diameter
• Spot is larger then 6 mm in diameter
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