Transcript Document

PowerPoint® Lecture Slides
prepared by
Betsy C. Brantley
Valencia College
CHAPTER
4
The
Integumentary
System
© 2013 Pearson Education, Inc.
Chapter 4 Learning Outcomes
• Section 1: Functional Anatomy of the Skin
• 4.1
• Describe the main structural features of the epidermis, and
explain the functional significance of each.
• 4.2
• Explain what accounts for individual differences in skin color
and compare various types of skin cancer.
• 4.3
• Describe the structure and functions of the dermis and
hypodermis.
• 4.4
• Describe the interaction between sunlight and endocrine
functioning as they relate to the skin.
© 2013 Pearson Education, Inc.
Chapter 4 Learning Outcomes
• Section 2: Accessory Organs of the Skin
• 4.5
• Explain the mechanisms of hair production, and explain the
structural basis for hair texture and color.
• 4.6
• Describe the various kinds of exocrine glands in the skin, and
discuss the secretions of each.
• 4.7
• Explain the anatomy of a typical nail.
• 4.8
• CLINICAL MODULE Summarize the effects of aging on the
skin.
• 4.9
• CLINICAL MODULE Explain how the skin responds to injury
and the steps by which it repairs itself.
© 2013 Pearson Education, Inc.
Functional Anatomy of the Skin (Section 1)
• Integumentary system (integument)
• Body's first line of defense
• Composed of:
• Cutaneous membrane (skin)
• Accessory structures (hair, nails, exocrine glands)
© 2013 Pearson Education, Inc.
Cutaneous Membrane (Section 1)
• Epidermis
• Stratified squamous epithelium
• Dermis
• Papillary layer of areolar tissue
• Reticular layer of dense irregular connective tissue
• Hypodermis or subcutaneous layer
• Connective tissue deep to integument
© 2013 Pearson Education, Inc.
Accessory Structures (Section 1)
• Include:
• Hair
• Nails
• Exocrine glands
• Cutaneous plexus
• Network of arteries and veins associated with integumentary
tissues
© 2013 Pearson Education, Inc.
Functional anatomy of the skin
Cutaneous
Membrane
Accessory
Structures
Hair shaft
Epidermis
Dermis
Pore of sweat
gland duct
Papillary
layer
Reticular
layer
Touch and
pressure receptors
Sebaceous gland
Arrector pili muscle
Sweat gland duct
Hair follicle
Hypodermis, or
subcutaneous layer
Nerve fibers
Sweat gland
Fat
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Artery
Vein
Figure 4 Section 1 1 1
Integumentary System Functions
(Section 1)
• Protection
• Protects underlying tissues and organs from impact,
abrasion, fluid loss, chemical attack
• Produces melanin, which protects underlying tissue from UV
radiation
• Produces keratin, which protects against abrasion and repels
water
• Coordinates immune response to pathogens and skin cancer
• Excretion
• Excretes salts, water, organic wastes
© 2013 Pearson Education, Inc.
Integumentary System Functions
(Section 1)
• Body temperature regulation
• Maintains normal body temperature through insulation
or evaporative cooling
• Vitamin D3 synthesis
• Converted to calcitriol, important in calcium metabolism
• Lipid storage
• Stored in adipocytes in dermis and hypodermis
• Sensory input
• Detects touch, pressure, pain, temperature
© 2013 Pearson Education, Inc.
Epidermis (4.1)
• Primary cell type in epidermis is keratinocyte
• Body's most abundant epithelial cell
• Multiple layers of cells (stratified squamous
epithelium)
• Stem cells in deepest layers
• Keratinocytes shed at exposed surface
• Epidermal ridges adjacent to dermal papillae
• Increase surface area for better attachment
© 2013 Pearson Education, Inc.
Dermal papillae
Epidermis
Epidermal
ridge
Dermal
papilla
Dermis
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Figure 4.1 11
Thin Skin (4.1)
• Covers most of body surface
• Four strata (layers)
• Epidermis as thick as a plastic sandwich bag
(~0.08 mm)
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Micrograph of thin skin
Epidermis
Dermis
Thin skin LM x 225
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Figure 4.1 22
Thick Skin (4.1)
• Found on palms of hands and soles of feet
• Five strata (layers)
• Epidermis as thick as a paper towel (~0.5 mm)
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Micrograph of thick skin
Epidermis
Dermal papilla
Epidermal ridge
Thick skin
© 2013 Pearson Education, Inc.
LM x 225
Figure 4.1 33
Characteristics of the Epidermis (4.1)
• Entire epidermis lacks blood vessels
• Cells get oxygen and nutrients from dermis
• Cells with highest metabolic demand closest to
dermis
• Takes 7–10 days for cells to move from deepest
layer (stratum basale) to most superficial layer
(stratum corneum)
© 2013 Pearson Education, Inc.
Layers of the Epidermis (4.1)
• Stratum basale
• Deepest layer of epidermis
• Attached to basement membrane by hemidesmosomes
• Most cells here are basal cells, stem cells that divide to
replace more superficial keratinocytes
• Merkel cells that respond to touch are also found here
• Stratum spinosum
• "Spiny layer" composed of 8–10 layers of keratinocytes
• Only looks spiny when on a prepared slide
• Contains dendritic cells, part of immune response
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Layers of the Epidermis (4.1)
• Stratum granulosum
• "Grainy layer" composed of 3–5 layers of keratinocytes
• Most cells have stopped dividing and started making keratin
• Cells grow thinner, flatter with thick and less permeable membranes
• Stratum lucidum
• "Clear layer" found only in thick skin
• Layer of flattened, densely packed dead cells filled with keratin
• Stratum corneum
• 15–30 layers of keratinized cells (filled with keratin)
• Cells are dead but still tightly connected by desmosomes
© 2013 Pearson Education, Inc.
Layers of the epidermis
Layers of the
Epidermis
Stratum corneum
Stratum lucidum
Stratum
granulosum
Stratum spinosum
Stratum basale
Papillary layer of dermis
LM x 470
© 2013 Pearson Education, Inc.
4
Figure 4.1 34
Fingerprints (4.1)
• Ridge patterns in thick skin on surface of fingertips
• Pattern produces fingerprints
• Fingerprints used to identify individuals
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Ridges patterns on fingertips
SEM x 25
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4
Figure 4.1 35
Module 4.1 Review
a. Identify the layers of the epidermis of thick skin
(from deep to superficial).
b. Dandruff is caused by excessive shedding of
cells from the outer layers of the skin of scalp.
Thus, dandruff is composed of cells from which
epidermal layer?
c. A splinter penetrates to the third layer of the
epidermis of the palm. In which layer does it
lodge?
© 2013 Pearson Education, Inc.
Skin Color (4.2)
• Skin color is determined by:
• Pigments in the skin
• Carotene
• Melanin
• Degree of dermal circulation
• Difference in skin pigmentation results from
different levels of pigment production, not different
numbers of melanocytes
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Epidermal pigmentation
Melanocytes
in stratum basale
Melanin pigment
Basement membrane
Thin skin
© 2013 Pearson Education, Inc.
LM x 400
4
Figure 4.2 31
Skin Pigments (4.2)
• Carotene
• Orange-yellow pigment
• Most apparent in stratum corneum of light-skinned people
• Found in orange vegetables
• Melanin
• Brown, yellow-brown, or black pigment
• Produced by melanocytes, located in stratum basale
• Packaged into melanosomes; transferred to keratinocytes where it
offers protection for nucleus against UV radiation
• Larger melanosomes result in darker skinned individuals
© 2013 Pearson Education, Inc.
A melanocyte in the stratum basale
3
Keratinocyte
1
Melanosomes transferred
to keratinocytes
Melanin produced by
melanocytes
2
4
Carotene is an
orange-yellow
pigment
Melanin packaged
in melanosomes
Basement membrane
© 2013 Pearson Education, Inc.
4
Figure 4.2 31
Dermal Circulation (4.2)
• Hemoglobin is red pigment found in red blood cells
• Blood flows to dermis through papillary plexus
• More blood flow to region results in redder color
• Flushed skin with fever from dilated superficial blood vessels
• Less blood flow to region results in cyanosis
• Lower oxygen levels makes hemoglobin darker red
• From surface view, skin has bluish color
• Most apparent in very thin skin (lips, beneath nails)
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Dermal circulation affects skin color
Hair
Capillary
loop of
papillary
plexus
Papillary plexus
Papillary
layer
Cutaneous
plexus
© 2013 Pearson Education, Inc.
4
Figure 4.2 32
Skin Cancers (4.2)
• Skin cancers most common types of cancers
• Basal cell carcinoma
• Most common form of skin cancer
• Originates in stratum basale and rarely metastasizes
• Result of mutation caused by overexposure to UV radiation
• Squamous cell carcinoma
• Second most common form of skin cancer
• Found in areas of sun-exposed skin
• More likely to metastasize than basal cell carcinoma
• Treatment for both types is surgical removal of
tumor
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Basal cell carcinoma
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4
Figure 4.2 33
Malignant Melanoma (4.2)
• Most serious form of skin cancer
• Cancerous melanocytes grow rapidly and metastasize
through lymphatic system
• If detected early and removed surgically, the 5-year
survival rate is 99 percent
• If not detected until after metastasis, the 5-year survival
rate is 14 percent
• Key characteristics
• Irregular in shape, border, color
• More than 5 mm in diameter
• Raised beyond skin surface
© 2013 Pearson Education, Inc.
Malignant melanoma
© 2013 Pearson Education, Inc.
4
Figure 4.2 34
Module 4.2 Review
a. Name the two pigments contained in the
epidermis.
b. Why does exposure to sunlight or sunlamps
darken skin?
c. Rank the three skin cancers according to their
health risk.
© 2013 Pearson Education, Inc.
Dermis (4.3)
• Between epidermis and hypodermis
• Two fiber types
1. Elastic fibers stretch and recoil to original length
• Allow flexibility in dermis
2. Collagen fibers are strong, resist stretching, and
bend easily
• Limit flexibility in dermis and prevent damage
© 2013 Pearson Education, Inc.
Epidermis, dermis, and hypodermis
Epidermal
ridges
Dermal
papillae
Papillary
layer
Reticular
layer
Capillary
network
Hypodermis
© 2013 Pearson Education, Inc.
4
Figure 4.3 31
Dermal Layers (4.3)
• Papillary layer (named after dermal papillae)
• Composed of areolar tissue
• Contains capillaries, lymphatic vessels, sensory neurons, and touch
receptors
• Reticular layer
• Interwoven meshwork of dense irregular connective tissue
• Collagen fibers from this layer blend into both papillary layer above
and hypodermis below
• Contains blood vessels, nerve fibers, and accessory organs
© 2013 Pearson Education, Inc.
Micrograph of reticular layer of dermis
Reticular layer of dermis SEM x 1500
© 2013 Pearson Education, Inc.
4
Figure 4.3 32
Hypodermis (4.3)
• Separates skin from deeper structures
• Stabilizes position of skin relative to underlying
tissues
• Often dominated by adipose tissue
• Site for storing energy
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Micrograph of hypodermis
Adipocytes
Hypodermis
© 2013 Pearson Education, Inc.
SEM x 250
4
Figure 4.3 33
Module 4.3 Review
a. Describe the location of the dermis.
b. Where are the capillaries and sensory neurons
that supply the epidermis located?
c. What accounts for the ability of the dermis to
undergo repeated stretching?
© 2013 Pearson Education, Inc.
Vitamin D and Sunlight (4.4)
• Two sources of vitamin D3
• Sunlight
• Epidermal cells in stratum spinosum and stratum basale
convert steroid compound into vitamin D3
• Vitamin diffuses across basement membrane and into
capillaries
• Diet
• Fish, fish oils, shellfish
• Foods "fortified with vitamin D" like milk and orange juice
© 2013 Pearson Education, Inc.
Vitamin D and Calcium (4.4)
• Liver converts vitamin D3 to intermediary product
• Kidney uses that product to synthesize calcitriol
• Calcitriol stimulates calcium and phosphorus
absorption by small intestines
• Bones use calcium and phosphorus for growth
and maintenance
© 2013 Pearson Education, Inc.
Sources of Vitamin D
Sources of Vitamin D3
Food
Sunlight
Steroid compound
Epidermis
Vitamin D3
Dietary
vitamin D3
Digestive tract
Liver
Intermediary
product
Stimulates
calcium and
phosphorus
absorption
Calcitriol
Kidney
© 2013 Pearson Education, Inc.
4
Figure 4.4 31
Inadequate Vitamin D (4.4)
• Lack of sunlight exposure and low vitamin D3 in
diet
• Inadequate vitamin D3 means inadequate calcium
and phosphorus
• Results in flexible, poorly mineralized bone
• In a growing child, causes rickets
• In adults, causes decreased bone density and
increased risk of fractures
• Elderly at higher risk with 75 percent decline in
skin production of vitamin D3
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Patient with rickets
© 2013 Pearson Education, Inc.
4
Figure 4.4 32
Module 4.4 Review
a. Describe two sources of vitamin D3.
b. Explain the relationship between sunlight
exposure and vitamin D3.
c. In some cultures, females must be covered from
head to toe when they go outdoors. Explain why
these women are at increased risk of developing
bone problems later in life.
© 2013 Pearson Education, Inc.
Accessory Organs of the Skin (Section 2)
• Hair follicles
• Exocrine glands
• Nails
© 2013 Pearson Education, Inc.
Integumentary system components
Epidermis
• Protects dermis from trauma and chemicals
• Controls skin permeability and prevents water loss
• Prevents entry of pathogens
• Synthesizes vitamin D3
• Sensory receptors detect touch, pressure, pain, and temperature
• Coordinates immune response to pathogens and skin cancers
Cutaneous
membrane
Integumentary
System
• Protects from
environmental hazards
• Excretes salts, water,
and wastes
• Maintains body
temperature
(thermoregulation)
• Produces melanin
• Produces keratin
• Synthesizes vitamin D3
• Stores lipids
• Detects sensory
information
• Coordinates immune
response
Dermis
Papillary Layer
Reticular Layer
• Nourishes and
supports
epidermis
• Restricts spread of pathogens that penetrate
epidermis
• Stores lipid reserves
• Attaches skin to deeper tissues
• Sensory receptors detect touch, pressure,
pain, vibration, and temperature
• Blood vessels assist in thermoregulation
Hair Follicles
• Produce hairs that protect skull
• Produce hairs that provide delicate touch
sensations on general body surface
Exocrine Glands
• Assist in thermoregulation
• Excrete wastes
• Lubricate epidermis
Accessory
structures
Nails
• Protect and support tips of fingers and toes
© 2013 Pearson Education, Inc.
Figure 4 Section 2 1 1
Hair (4.5)
• Found almost everywhere on body
• Produced by hair follicle
• Follicle composed of epithelial and connective tissues
• Parts of a hair
• Hair shaft is partly visible on the surface
• Hair root anchors hair into skin
• Root hair plexus is group of sensory nerves surrounding
base of follicle
• Arrector pili is smooth muscle attached to follicle;
contraction causes "goosebumps"
© 2013 Pearson Education, Inc.
Single hair follicle
Sebaceous gland
Hair shaft
Hair root
Connective
tissue
sheath
Root hair
plexus
Arrector pili muscle
© 2013 Pearson Education, Inc.
4
Figure 4.5 31
Hair Structure (4.5)
• Hair papilla
• Peg of connective tissue filled with blood vessels and nerves at
base of follicle
• Matrix
• Growth zone of hair
• Medulla
• Core of hair at center of hair matrix
• Cortex
• Intermediate layer deep to cuticle
• Cuticle
• Forms surface of the hair
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Sectional view of hair follicle
Cuticle
Cortex
Medulla
Matrix
Hair papilla
© 2013 Pearson Education, Inc.
4
Figure 4.5 32
Keratin in Hair (4.5)
• Medulla
• Contains flexible, soft keratin
• Cortex
• Contains thick layers of hard keratin
• Gives hair stiffness
• Cuticle
• Contains very hard keratin
• Very tough
© 2013 Pearson Education, Inc.
Hair follicle structures with cross section
Sebaceous gland
Hair Structure
Medulla Cortex Cuticle
Hair shaft
Hair
follicle
Hair root
Connective
tissue
sheath
Root hair
plexus
Arrector pili muscle
© 2013 Pearson Education, Inc.
Figure 4.5 11- 3– 3
Hair Growth Cycle (4.5)
• Hairs grow and are shed in the hair growth cycle
• Active phase
• Lasts 2–5 years
• Hair grows at rate of 0.33 mm/day
• Resting phase
• Hair loses attachment to follicle
• Becomes club hair
• When follicle reactivated, club hair shed and replacement
hair formation begins
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Hair growth cycle
2
Regression
and transition
3
1
Active phase
2
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Resting
phase
Follicle
reactivation
and growth of
replacement hair
4
Figure 4.5 34
Hair Color (4.5)
• Variations in hair color are due to melanin
variations
• Different forms of melanin give:
• Dark brown
• Yellow-brown
• Red
• Pigment production declines with age, lightening
color
• White hair from lack of pigment and air bubbles in
medulla of hair shaft
© 2013 Pearson Education, Inc.
Module 4.5 Review
a. Describe a typical strand of hair.
b. What happens when an arrector pili muscle
contracts?
c. Pulling a hair is painful, but cutting a hair is not.
Why?
© 2013 Pearson Education, Inc.
Sebaceous Glands (4.6)
• Discharge sebum through holocrine secretion
• Mixture of triglycerides, cholesterol, proteins, and electrolytes
• Coats hair shaft and surrounding epidermal surfaces
• Provides lubrication
• Keeps hair shaft from becoming dry and brittle
• Has antibacterial properties
• Contraction of arrector pili muscles squeezes sebaceous
glands, forcing sebum into hair follicle
• Also secrete sebum onto skin surface on face, back, chest,
nipples, and external genitalia
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Sebaceous glands
Sebaceous Glands
Typical Sebaceous Glands
Sebaceous gland
Sebaceous Follicles
Hair removed
Wall of hair follicle
Basement membrane
Discharge of sebum
Lumen
Breakdown of
cell membranes
Mitosis and growth
Basal cells
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4
Figure 4.6 31
Sweat Glands (4.6)
• Apocrine sweat glands
• Found in armpits, nipples, pubic region
• Secrete onto hair follicles
• Produce sticky, cloudy, odorous secretion
• Merocrine sweat glands
• Found all over body; highest concentration in palms and
soles
• Secrete directly onto skin surface
• Produce watery secretions with electrolytes to help regulate
body temperature
© 2013 Pearson Education, Inc.
Sweat glands
Sweat Glands
Apocrine Sweat Glands
Connective
tissue of
dermis
Apocrine
gland cells
Merocrine Sweat Glands
Merocrine
gland cells
Lumen
Lumen
Section
LM x 375
of
apocrine
sweat gland
© 2013 Pearson Education, Inc.
Sweat
pore
Section LM x 210
of
merocrine
sweat gland
4
Figure 4.6 32
Module 4.6 Review
a. Identify two types of exocrine glands found in the
skin.
b. What are the functions of sebaceous secretions?
c. Deodorants are used to mask the effects of
secretions from which type of skin gland?
© 2013 Pearson Education, Inc.
Nails (4.7)
• Protect tips of fingers and toes
• Nail body is thick sheets of dead, keratinized
epidermal cells
• Nail bed is area of epidermis under nail body
• Nail production occurs at nail root
• Cuticle is portion of stratum corneum of nail
extending over nail root
• Pale arched area near nail root is lunula
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Common landmarks of nail structure
1
Nail bed
Nail body
Direction
of growth
Free edge
of nail body
3
2
Underlying blood
vessels give the
nail its pink
appearance.
Lunula
Proximal nail
fold
Cuticle
4
5
Proximal nail fold
Phalanx
(bone of
fingertip)
Cuticle
Lunula Nail body
Nail root
Epidermis Dermis Phalanx
© 2013 Pearson Education, Inc.
4
Figure 4.7 31
Changes in Nail Appearance (4.7)
• Any health condition altering body metabolism
may alter nail appearance
• Changes in nail shape, structure, or appearance
give diagnostic information
• Psoriasis causes rapid stem cell division at
stratum basale, resulting in distorted and pitted
nails
• Concave nails may be from blood disorder
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Altered nail appearance with psoriasis
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4
Figure 4.7 32
Module 4.7 Review
a. Define nail bed.
b. Describe a typical fingernail.
c. Where does nail production occur?
© 2013 Pearson Education, Inc.
Age-Related Changes in the Integument (4.8)
• Melanocyte activity declines so skin is more sensitive to sun exposure
and at risk for sunburn
• Sebaceous glands secrete less sebum so skin is dry and scaly
• Increased risk of skin injury, tears, and infection
• Basal cell activity declines so there are fewer epidermal
cells
• Weakened connections between epidermis and dermis
• Declining metabolic activity (less vitamin D3 production)
© 2013 Pearson Education, Inc.
Age-Related Changes in the Integument (4.8)
• Decreasing numbers of dendritic cells decrease
immune response
• Dermis thins and has fewer elastic fibers resulting
in sagging and wrinkling
• Merocrine sweat glands are less active so there is
a greater risk of overheating
• Reduced blood supply to dermis affects
temperature regulation
© 2013 Pearson Education, Inc.
Age-Related Changes in the Integument (4.8)
• Skin repair slows
• Hair follicles stop functioning or produce thinner
hair
• Decreased melanocyte activity, so gray or white hairs
• Changing levels of sex hormones alter hair and fat
distribution
© 2013 Pearson Education, Inc.
Age-related changes in the integument
Fewer
Melanocytes
Drier
Epidermis
Thinning
Epidermis
Diminished Immune
Response
Thinning
Dermis
Decreased
Perspiration
Altered Hair and
Fat Distribution
© 2013 Pearson Education, Inc.
Fewer Active
Follicles
Slower Skin
Repair
Reduced Blood
Supply
Figure 4.8 3
Module 4.8 Review
a. Identify some common effects of the aging
process on skin.
b. Why does hair turn white or gray with age?
c. Why do we tolerate summer heat less well and
become more susceptible to heat-related illness
when we become older?
© 2013 Pearson Education, Inc.
Integument Repair (4.9)
• Initial injury to skin causes bleeding and release of
mast cells
• After several hours:
• Blood clot or scab forms at surface
• Cells of stratum basale migrate along wound edges
• Macrophages remove debris
• If damage into dermis, combination of fibroblasts, blood
clot, and capillary network form granulation tissue as
part of repair process
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Integument Repair (4.9)
• After one week:
• Scab undermined by migrating epidermal cells
• Phagocytic activity almost complete
• Blood clot disintegrating
• Fibroblasts have formed collagen fibers and ground
substance
• After several weeks:
• Scab is shed; epidermis is complete
• Shallow depression marks injury site
• Fibroblasts continue to create scar tissue – inflexible,
fibrous, noncellular material
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Repair of injury to the integument
After One Week
Initial Injury
After Several Hours
Mast cells trigger
inflammatory
Bleeding
response
occurs at the
site of injury.
Scab forms at the surface
Epidermis
Patrolling
macrophages
Dermis
Rapid cell
division and
migration
along wound
edges
After Several Weeks
Deeper portions of the clot
dissolve. Fibroblasts deposit
collagen fibers and ground
substance.
Fibroblasts
Scar tissue formation
Scar
tissue
Formation of
granulation tissue
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Figure 4.9 11- 4– 4
Scar Tissue (4.9)
• Formation of scar tissue part of tissue repair
• Hair follicles, sebaceous or sweat glands, muscle
cells, nerves often replaced by scar tissue
• Scar tissue forming beyond repair area is keloid
• Harmless raised, thickened mass of scar tissue
• Covered by shiny, smooth epidermal surface
• Most common on upper back, shoulders, anterior chest,
earlobes
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Adult with keloid scar tissue
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4
Figure 4.9 35
Module 4.9 Review
a. Identify the first step in the repair of an injury to
the skin.
b. Describe granulation tissue.
c. Why can skin regenerate effectively even after
considerable damage?
© 2013 Pearson Education, Inc.