Download Skin and Body Membranes

Essentials of Human Anatomy & Physiology
Seventh Edition
Elaine N. Marieb
Chapter 4
Skin and Body Membranes
Slides 4.1 – 4.44
Lecture Slides in PowerPoint by Jerry L. Cook
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Skin and Body Membranes
 Body membranes cover surfaces, line
body cavities, and form protective
sheets around organs
 Function of body membranes
 Line or cover body surfaces
 Protect body surfaces
 Lubricate body surfaces
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Slide 4.2
Classification of Body Membranes
 Epithelial membranes
 Cutaneous membrane
 Mucous membrane
 Serous membrane
 Connective tissue membranes
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Slide 4.3
Cutaneous Membrane
 Cutaneous membrane = skin
 A dry membrane
 Outermost protective boundary
 Superficial epidermis
 Keratinized stratified
squamous epithelium
 Underlying dermis
 Mostly dense (fibrous)
connective tissue
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Figure 4.1a
Slide 4.4
Mucous Membranes
 Surface epithelium
 Type depends on site
 Underlying loose connective tissue
(lamina propria)
 Lines all body cavities that
open to the exterior body
surface
 Often adapted for absorption
or secretion
 Wet membranes bathed in
secretions
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Figure 4.1b
Slide 4.5
Serous Membranes
 Surface simple squamous
epithelium
 Underlying areolar connective
tissue
 Lines open body cavities that
are closed to the exterior of
the body
 Occur in pairs – parietal and
visceral
 Serous layers separated by
serous fluid
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Figure 4.1c
Slide 4.6
Serous Membranes
 Specific serous membranes
 Peritoneum
 Abdominal
cavity
 Pleura
 Around the
lungs
Figure 4.1d
 Pericardium
 Around the
heart
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Slide 4.7
Connective Tissue Membrane
 Synovial membrane
 Areolar connective
tissue only
 Lines fibrous capsules
surrounding joints
 Line small sac of
connective tissue
called bursae and the
tube-like tendon
sheaths
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Figure 4.2
Slide 4.8
Integumentary System
 Skin (cutaneous membrane)
 Skin derivatives
 Sweat glands
 Oil glands
 Hairs
 Nails
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Slide 4.9
Skin Functions
 Protects deeper tissues from:
 Mechanical damage
 Chemical damage
 Bacterial damage
 Thermal damage
 Ultraviolet radiation
 Desiccation
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Slide 4.10
Skin Functions
 Protective and cushioning
 Waterproof
 Aids in heat regulation
 Aids in excretion of salts, urea and uric
acid
 Synthesizes vitamin D
 Contains sensory receptors
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Slide 4.11
Skin Structure
 Epidermis – outer layer
 Stratified squamous epithelium
 Often keratinized (hardened by keratin)
 Dermis
 Dense connective tissue
 Both firmly connected but can separate such
as in a blister
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Slide 4.12
Skin Structure
 Deep to dermis is the hypodermis
 Not part of the skin
 Anchors skin to underlying organs
 Composed mostly of adipose tissue
 Serves as shock absorber and insulation
for deeper tissues
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Slide 4.13
Layer of Epidermis
 Stratum basale – deepest layer
 Cells undergoing mitosis
 Lies next to dermis and receives nutrients
from the dermis by diffusion
 Stratum spinosum – old stratum basale cells
 Stratum granulosum – old stratum spinosum
cells
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Slide 4.14
Layer of Epidermis
 Stratum lucidum
 Occurs only in thick, hairless skin
 Stratum corneum
 Shingle-like dead cells that are ¾ of the
epidermal thickness
 Completely filled with keratin cells called
cornified or horny cells
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Slide 4.15
Melanin
 Pigment (melanin) produced by melanocytes
 Color is yellow to brown to black
 Melanocytes are mostly in the stratum
basale
 Amount of melanin produced depends upon
genetics and exposure to sunlight
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Slide 4.16
Dermis – the “hide”
 Two layers
Papillary layer
 Projections called dermal papillae
 Pain receptors and touch receptors
 Capillary loops for nutrients
 Result in fingerprints
Reticular layer
 Blood vessels
 Sweat and oil glands
 Nerve receptors
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Slide 4.17
Dermis – the “hide”
 Both collagen and elastic fibers are found in
the dermis
 Collagen – responsible for the toughness
of the dermis and for binding water to keep
it hydrated
 Elastic fibers – give skin elasticity when we
are young but lessens as we age along
with collagen
 Lots of blood vessels play a role in
maintaining body temperature
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Slide 4.18
Skin Structure
Figure 4.4
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Slide 4.19
Normal Skin Color Determinants
 Melanin – amount and kind
 Yellow, brown or black pigments
 Carotene
 Orange-yellow pigment from some
vegetables
 Hemoglobin
 Red coloring from blood cells in dermis
capillaries
 Oxygen content determines the extent of red
coloring
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Slide 4.20
Normal Skin Color Determinants
 Redness or erythema – blushing
 Pallor or blanching – pale from fear or
anemia, low blood pressure, or impaired
blood flow
 Jaundice or yellow cast – liver disorder
where excess bile pigments are absorbed in
the blood
 Bruises or black-and-blue marks – where
blood has escaped from vessels and clotted
in the tissue spaces – called hematomas
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Slide 4.21
Appendages of the Skin
 Arise from the epidermis and play a role
in maintaining homeostasis of the body
 Cutaneous glands – exocrine glands
 Release their secretions to the skin
surface via ducts
 Sebaceous glands and sweat
glands
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Slide 4.22
Appendages of the Skin
 Sebaceous glands
 Produce oil - sebum
 Lubricant for skin
 Kills bacteria
 Prevents hair from becoming brittle
 Most with ducts that empty into hair follicles
 Glands are activated at puberty
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Slide 4.23
Appendages of the Skin
 Sweat glands – sudoriferous glands
 Widely distributed in skin
 Two types
 Eccrine
 Open via duct to pore on skin surface
 Apocrine
 Ducts empty into hair follicles
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 4.24
Sweat and Its Function
 Composition
 Mostly water with some salts and vitamin C
 Some metabolic waste and lactic acid
 Fatty acids and proteins (apocrine only), which
may have a milky or yellowish color
 Function
 Helps dissipate excess heat – eccrine only
 Excretes waste products
 Acidic nature inhibits bacteria growth
 Odor is from associated bacteria living off
proteins and fats
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Slide 4.25
Appendages of the Skin
 Hair
 Serves a few minor protective functions
 Used to serve as insulation and still does in
some animals
 Produced by a hair follicle – flexible epithelial
structure
 Part of the hair enclosed in the follicle is the
root
 Part projecting from the surface of the scalp
is the shaft
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Slide 4.26
Appendages of the Skin
 Hair
 Produced by
hair bulb matrix
 Consists of hard
keratinized
epithelial cells
 Melanocytes
provide pigment
for hair color
Figure 4.7c
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Slide 4.27
Hair Anatomy
 Central core called the medulla
 Cortex surrounds medulla
 Cuticle on outside of cortex
formed from a single layer of cells
that overlap like shingles on a
roof to keep hairs separated
 Most heavily keratinized to provide
strength
 Worn more at tips to cause split
ends
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 4.7b
Slide 4.28
Associated Hair Structures
 Hair follicle
 Dermal (provides blood
vessels) and epidermal sheath
surround hair root
 Arrector pilli
 Smooth muscle cause the hair
to stand up – goose bumps
 Sebaceous (oil) gland
 Sweat gland
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 4.7a
Slide 4.29
Nail Structures
 Each nail has three
parts
 Free edge
 Body
 Root of nail
 Eponychium – proximal
nail fold that projects onto
the nail body – often
called cuticle
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Figure 4.9
Slide 4.30
Appendages of the Skin
 Nails
 Scale-like modifications of the epidermis
 Heavily keratinized
 Stratum basale extends beneath the nail bed
 The thickened proximal area called the nail matrix
is responsible for nail growth
 Lack of pigment makes them colorless
 Appear pink due to blood vessels underneath
 White crescent – lunula – thickened nail matrix
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Slide 4.31
Skin Homeostatic Imbalances
 Infections
 Athletes foot – tinea pedis
 Caused by fungal infection on feet
 Boils and carbuncles
 Caused by bacterial infection –
Staphylococcus aureus – in hair follicles and
sebaceous glands
 Cold sores – fever blisters
 Caused by herpes simplex viral infection
usually on lips and in oral mucosa of the
mouth
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Slide 4.32
Skin Homeostatic Imbalances
 Infections and allergies
 Contact dermatitis
 Exposures to certain chemicals cause allergic
reaction
 Impetigo
 Pink, water-filled, raised lesions around the mouth
caused by staphylococcus bacterial infection
 Psoriasis
 Cause is unknown but chronic
 Triggered by trauma, infection, stress
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Slide 4.33
Skin Homeostatic Imbalances
 Burns
 Tissue damage and cell death caused by heat,
electricity, UV radiation, or chemicals
 Nearly every body system is affected when skin
is severely damaged
 Associated dangers
 Dehydration
 Electrolyte
imbalance
 Circulatory
shock
 Infection
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Slide 4.34
Rules of Nines
 Way to determine the
extent of burns
 Body is divided into 11
areas for quick estimation
 Each area represents
about 9%
 Rule of nines
 Classified according to their
severity (depth)
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Slide 4.35
Severity of Burns
 First-degree burns
 Only epidermis is damaged
 Skin is red and swollen
 Partial-thickness burn that heals quickly
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Slide 4.36
Severity of Burns
 Second degree burns
 Epidermis and upper dermis are damaged
 Skin is red with blisters
 Partial-thickness burn that heals w/o scar
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Slide 4.37
Severity of Burns
 Third-degree burns
 Destroys entire skin layer
 Burn is gray-white or black
 Nerve endings destroyed so not painful
 Full-thickness burn that does not heal and grafting is
necessary
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Slide 4.38
Severity of Burns
•Fourth-degree burns
•Extend through the skin to injure muscle,
ligaments, tendons, nerves, blood vessels, and
bones
•These burns always require medical treatment
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Slide 4.39
Critical Burns
 Burns are considered critical if:
 Over 25% of body has second degree
burns
 Over 10% of the body has third degree
burns
 There are third degree burns of the face,
hands, or feet
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Slide 4.40
Skin Cancer
 Cancer – abnormal cell mass
 Two types
 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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Slide 4.41
Skin Cancer Types
 Basal cell carcinoma
 Least malignant
 Most common type
 Arises from stratum basale that no longer makes
keratin and stays in place
 Squamous cell carcinoma
 Arises from stratum spinosum
 Metastasizes to lymph nodes
 Early removal allows a good chance of cure
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Slide 4.42
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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Slide 4.43
ABCD Rule
 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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Slide 4.44