Essentials of Human Anatomy & Physiology
Seventh Edition
Elaine N. Marieb
Chapter 4
Skin and Body Membranes
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slides 4.1 – 4.44
Skin and Body Membranes
Lecture Slides in PowerPoint by Jerry L. Cook
Skin and Body MembranesSkin and Body Membranes
Body membranes cover surfaces, linebody cavities, and form protectivesheets around organs
Function of body membranes
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Function of body membranes
Line or cover body surfaces
Protect body surfaces
Lubricate body surfaces
Classification of Body MembranesClassification of Body Membranes
Epithelial membranes
Cutaneous membrane
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Mucous membrane
Serous membrane
Connective tissue membranes
Cutaneous MembraneCutaneous Membrane
Cutaneous membrane = skin
A dry membrane
Outermost protective boundary
Superficial epidermis
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Superficial epidermis
Keratinized stratifiedsquamous epithelium
Underlying dermis
Mostly dense (fibrous)connective tissue
Figure 4.1a
Mucous MembranesMucous Membranes Surface epithelium
Type depends on site
Underlying loose connective tissue(lamina propria)
Lines all body cavities that
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Figure 4.1b
Lines all body cavities thatopen to the exterior bodysurface
Often adapted for absorptionor secretion
Wet membranes bathed insecretions
Serous MembranesSerous Membranes Surface simple squamous
epithelium
Underlying areolar connectivetissue
Lines open body cavities that
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Figure 4.1c
Lines open body cavities thatare closed to the exterior ofthe body
Occur in pairs – parietal andvisceral
Serous layers separated byserous fluid
Serous MembranesSerous Membranes
Specific serous membranes
Peritoneum
Abdominalcavity
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Pleura
Around thelungs
Pericardium
Around theheart
Figure 4.1d
Connective Tissue MembraneConnective Tissue Membrane
Synovial membrane
Areolar connectivetissue only
Lines fibrous capsules
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Lines fibrous capsulessurrounding joints
Line small sac ofconnective tissuecalled bursae and thetube-like tendonsheaths
Figure 4.2
Integumentary SystemIntegumentary System
Skin (cutaneous membrane)
Skin derivatives
Sweat glands
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Sweat glands
Oil glands
Hairs
Nails
Skin FunctionsSkin Functions
Protects deeper tissues from:
Mechanical damage
Chemical damage
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Chemical damage
Bacterial damage
Thermal damage
Ultraviolet radiation
Desiccation
Skin FunctionsSkin Functions
Protective and cushioning
Waterproof
Aids in heat regulation
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Aids in heat regulation
Aids in excretion of salts, urea and uricacid
Synthesizes vitamin D
Contains sensory receptors
Skin StructureSkin Structure
Epidermis – outer layer
Stratified squamous epithelium
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Often keratinized (hardened by keratin)
Dermis
Dense connective tissue
Both firmly connected but can separate suchas in a blister
Skin StructureSkin Structure
Deep to dermis is the hypodermis
Not part of the skin
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Not part of the skin
Anchors skin to underlying organs
Composed mostly of adipose tissue
Serves as shock absorber and insulationfor deeper tissues
Layer of EpidermisLayer of Epidermis
Stratum basale – deepest layer
Cells undergoing mitosis
Lies next to dermis and receives nutrientsfrom the dermis by diffusion
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from the dermis by diffusion
Stratum spinosum – old stratum basale cells
Stratum granulosum – old stratum spinosumcells
Layer of EpidermisLayer of Epidermis
Stratum lucidum
Occurs only in thick, hairless skin
Stratum corneum
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Shingle-like dead cells that are ¾ of theepidermal thickness
Completely filled with keratin cells calledcornified or horny cells
MelaninMelanin
Pigment (melanin) produced by melanocytes
Color is yellow to brown to black
Melanocytes are mostly in the stratum
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Melanocytes are mostly in the stratumbasale
Amount of melanin produced depends upongenetics and exposure to sunlight
DermisDermis –– the “hide”the “hide” Two layers
Papillary layer
Projections called dermal papillae
Pain receptors and touch receptors
Capillary loops for nutrients
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Capillary loops for nutrients
Result in fingerprints
Reticular layer
Blood vessels
Sweat and oil glands
Nerve receptors
DermisDermis –– the “hide”the “hide”
Both collagen and elastic fibers are found inthe dermis
Collagen – responsible for the toughnessof the dermis and for binding water to keepit hydrated
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Elastic fibers – give skin elasticity when weare young but lessens as we age alongwith collagen
Lots of blood vessels play a role inmaintaining body temperature
Skin StructureSkin Structure
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Figure 4.4
Normal Skin Color DeterminantsNormal Skin Color Determinants
Melanin – amount and kind
Yellow, brown or black pigments
Carotene
Orange-yellow pigment from somevegetables
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Orange-yellow pigment from somevegetables
Hemoglobin
Red coloring from blood cells in dermiscapillaries
Oxygen content determines the extent of redcoloring
Normal Skin Color DeterminantsNormal Skin Color Determinants
Redness or erythema – blushing
Pallor or blanching – pale from fear oranemia, low blood pressure, or impairedblood flow
Jaundice or yellow cast – liver disorder
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Jaundice or yellow cast – liver disorderwhere excess bile pigments are absorbed inthe blood
Bruises or black-and-blue marks – whereblood has escaped from vessels and clottedin the tissue spaces – called hematomas
Appendages of the SkinAppendages of the Skin
Arise from the epidermis and play a rolein maintaining homeostasis of the body
Cutaneous glands – exocrine glands
Release their secretions to the skin
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Release their secretions to the skinsurface via ducts
Sebaceous glands and sweatglands
Appendages of the SkinAppendages of the Skin
Sebaceous glands
Produce oil - sebum
Lubricant for skin
Kills bacteria
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Kills bacteria
Prevents hair from becoming brittle
Most with ducts that empty into hair follicles
Glands are activated at puberty
Appendages of the SkinAppendages of the Skin
Sweat glands – sudoriferous glands
Widely distributed in skin
Two types
Eccrine
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Eccrine
Open via duct to pore on skin surface
Apocrine
Ducts empty into hair follicles
Sweat and Its FunctionSweat and Its Function Composition
Mostly water with some salts and vitamin C
Some metabolic waste and lactic acid
Fatty acids and proteins (apocrine only), whichmay have a milky or yellowish color
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Function
Helps dissipate excess heat – eccrine only
Excretes waste products
Acidic nature inhibits bacteria growth
Odor is from associated bacteria living offproteins and fats
Appendages of the SkinAppendages of the Skin Hair
Serves a few minor protective functions
Used to serve as insulation and still does insome animals
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Produced by a hair follicle – flexible epithelialstructure
Part of the hair enclosed in the follicle is theroot
Part projecting from the surface of the scalpis the shaft
Appendages of the SkinAppendages of the Skin
Hair
Produced byhair bulb matrix
Consists of hard
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Consists of hardkeratinizedepithelial cells
Melanocytesprovide pigmentfor hair color Figure 4.7c
Hair AnatomyHair Anatomy Central core called the medulla
Cortex surrounds medulla
Cuticle on outside of cortexformed from a single layer of cellsthat overlap like shingles on a
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Figure 4.7b
that overlap like shingles on aroof to keep hairs separated
Most heavily keratinized to providestrength
Worn more at tips to cause splitends
Associated Hair StructuresAssociated Hair Structures
Hair follicle
Dermal (provides bloodvessels) and epidermal sheathsurround hair root
Arrector pilli
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Figure 4.7a
Arrector pilli
Smooth muscle cause the hairto stand up – goose bumps
Sebaceous (oil) gland
Sweat gland
Nail StructuresNail Structures
Each nail has threeparts
Free edge
Body
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Body
Root of nail
Eponychium – proximalnail fold that projects ontothe nail body – oftencalled cuticle
Figure 4.9
Appendages of the SkinAppendages of the Skin
Nails
Scale-like modifications of the epidermis
Heavily keratinized
Stratum basale extends beneath the nail bed
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Stratum basale extends beneath the nail bed
The thickened proximal area called the nail matrixis responsible for nail growth
Lack of pigment makes them colorless
Appear pink due to blood vessels underneath
White crescent – lunula – thickened nail matrix
Skin Homeostatic ImbalancesSkin Homeostatic Imbalances Infections
Athletes foot – tinea pedis
Caused by fungal infection on feet
Boils and carbuncles
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Caused by bacterial infection –Staphylococcus aureus – in hair follicles andsebaceous glands
Cold sores – fever blisters
Caused by herpes simplex viral infectionusually on lips and in oral mucosa of themouth
Skin Homeostatic ImbalancesSkin Homeostatic Imbalances Infections and allergies
Contact dermatitis
Exposures to certain chemicals cause allergicreaction
Impetigo
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Impetigo
Pink, water-filled, raised lesions around the mouthcaused by staphylococcus bacterial infection
Psoriasis
Cause is unknown but chronic
Triggered by trauma, infection, stress
Skin Homeostatic ImbalancesSkin Homeostatic Imbalances
Burns
Tissue damage and cell death caused by heat,electricity, UV radiation, or chemicals
Nearly every body system is affected when skinis severely damaged
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is severely damaged
Associated dangers
Dehydration
Electrolyteimbalance
Circulatoryshock
Infection
Rules of NinesRules of Nines
Way to determine theextent of burns
Body is divided into 11areas for quick estimation
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areas for quick estimation
Each area representsabout 9%
Rule of nines
Classified according to theirseverity (depth)
Severity of BurnsSeverity of Burns
First-degree burns
Only epidermis is damaged
Skin is red and swollen
Partial-thickness burn that heals quickly
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Partial-thickness burn that heals quickly
Severity of BurnsSeverity 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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Partial-thickness burn that heals w/o scar
Severity of BurnsSeverity 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
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Full-thickness burn that does not heal and grafting isnecessary
Severity of BurnsSeverity of Burns
•Fourth-degree burns•Extend through the skin to injure muscle,ligaments, tendons, nerves, blood vessels, andbones•These burns always require medical treatment
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•These burns always require medical treatment
Critical BurnsCritical Burns
Burns are considered critical if:
Over 25% of body has second degreeburns
Over 10% of the body has third degree
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Over 10% of the body has third degreeburns
There are third degree burns of the face,hands, or feet
Skin CancerSkin Cancer
Cancer – abnormal cell mass
Two types
Benign
Does not spread (encapsulated)
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Does not spread (encapsulated)
Malignant
Metastasized (moves) to other parts ofthe body
Skin cancer is the most common type ofcancer
Skin Cancer TypesSkin Cancer Types
Basal cell carcinoma
Least malignant
Most common type
Arises from stratum basale that no longer makeskeratin and stays in place
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keratin and stays in place
Squamous cell carcinoma
Arises from stratum spinosum
Metastasizes to lymph nodes
Early removal allows a good chance of cure
Skin Cancer TypesSkin Cancer Types
Malignant melanoma
Most deadly of skin cancers
Cancer of melanocytes
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Cancer of melanocytes
Metastasizes rapidly to lymph and bloodvessels
Detection uses ABCD rule
ABCD RuleABCD Rule
A = Asymmetry
Two sides of pigmented mole do not match
B = Border irregularity
Borders of mole are not smooth
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Borders of mole are not smooth
C = Color
Different colors in pigmented area
D = Diameter
Spot is larger then 6 mm in diameter