Download CHAPTER 5: The Integumentary System

Unit
2
Support and Movement
Fundamentals of
Anatomy & Physiology
Frederic H. Martini
PowerPoint® Lecture Slides prepared by
Professor Albia Dugger, Miami–Dade College, Miami, FL
Professor Robert R. Speed, Ph.D., Wallace Community College, Dothan, AL
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Chapter 5:
The Integumentary System
What are the structures
and functions of the
integumentary system?
Size of the Integument
• The integument is the largest system
of the body:
– 16% of body weight
– 1.5 to 2 m2 in area
Parts of the Integument
• The integument is made up of
2 parts:
1. cutaneous membrane (skin)
2. accessory structures
Parts of the
Integumentary System
Figure 5–1
Parts of the
Cutaneous Membrane
• Outer epidermis:
– superficial epithelium (epithelial tissues)
• Inner dermis:
– connective tissues
Accessory Structures
• Originate in the dermis
• Extend through the epidermis to skin
surface:
– hair
– nails
– multicellular exocrine glands
Connections
• Circulatory system:
– blood vessels in the dermis
• Nervous system:
– sensory receptors for pain, touch, and
temperature
What is the relationship
between the integument
and subcutaneous layer?
The Subcutaneous Layer
• Subcutaneous layer (superficial fascia
or hypodermis):
– loose connective tissue
– below the dermis
– location of hypodermic injections
Functions of Skin
• Protects underlying tissues and organs
• Excretes salts, water, and organic
wastes (glands)
• Maintains body temperature (insulation
and evaporation)
Functions of Skin
• Synthesizes vitamin D3
• Stores lipids
• Detects touch, pressure, pain, and
temperature
What are the main
structures and functions
of the epidermis?
Epidermis
• Avascular stratified squamous
epithelium
• Nutrients and oxygen diffuse from
capillaries in the dermis
Organization of the Epidermis
Figure 5–2
Cells of the Epidermis
• Keratinocytes:
– contain large amounts of keratin
– the most abundant cells in the epidermis
Thin Skin
• Covers most of the body
• Has 4 layers of keratinocytes
Thick Skin
• Covers the palms of the hands and
soles of the feet
• Has 5 layers of keratinocytes
Structures of the Epidermis
• The 5 strata of keratinocytes in thick
skin
Figure 5–3
Layers of the Epidermis
• From basal lamina to free surface:
–
–
–
–
–
stratum
stratum
stratum
stratum
stratum
germinativum
spinosum
granulosum
lucidum
corneum
Stratum Germinativum
• The “germinative layer”:
– has many germinative (stem) cells or basal
cells
– is attached to basal lamina by
hemidesmosomes
– forms a strong bond between epidermis
and dermis
Structures of
Stratum Germinativum
• Epidermal ridges (e.g., fingerprints)
• Dermal papillae (tiny mounds):
– increase the area of basal lamina
– strengthen attachment between epidermis
and dermis
Ridges and Ducts
Figure 5–4
Cells of Stratum Germinativum
• Merkel cells:
– found in hairless skin
– respond to touch (trigger nervous system)
• Melanocytes:
– contain the pigment melanin
– scattered throughout stratum
germinativum
Stratum Spinosum
• The “spiny layer”:
– produced by division of stratum
germinosum
– 8–10 layers of keratinocytes bound by
desmosomes
– cells shrink until cytoskeletons stick out
(spiny)
Cells of Stratum Spinosum
• Continue to divide, increasing
thickness of epithelium
• Contain Langerhans cells, active in
immune response
Stratum Granulosum
• The “grainy layer”
• Stops dividing, starts producing:
– keratin:
• a tough, fibrous protein
• makes up hair and nails
– keratohyalin
• dense granules
• cross-link keratin fibers
Cells of Stratum Granulosum
• Produce protein fibers
• Dehydrate and die
• Create tightly interlocked layer of
keratin surrounded by keratohyalin
Stratum Lucidum
• The “clear layer”:
– found only in thick skin
– covers stratum granulosum
Cells of Stratum Lucida
• Flat
• Dense
• Filled with keratin
Stratum Corneum
• The “horn layer”:
–
–
–
–
exposed surface of skin
15 to 30 layers of keratinized cells
water resistant
shed and replaced every 2 weeks
Keratinization
• The formation of a layer of dead,
protective cells filled with keratin
• Occurs on all exposed skin surfaces
except eyes
Skin Life Cycle
• It takes 15–30 days for a cell to move
from stratum germinosum to stratum
corneum
Perspiration
• Insensible perspiration:
– interstitial fluid lost by evaporation
through the stratum corneum
• Sensible perspiration:
– water excreted by sweat glands
Water Loss Through Skin
• Dehydration results:
– from damage to stratum corneum, e.g.,
burns and blisters (insensible perspiration)
– from immersion in hypertonic solution,
e.g., seawater (osmosis)
Water Gain Through Skin
• Hydration:
– results from immersion in hypotonic
solution, e.g., freshwater (osmosis)
– causes stretching and wrinkling skin
What causes different
skin colors?
Skin Color
• Skin color depends on:
– the pigments carotene and melanin
– blood circulation (red cells)
Carotene
• Orange-yellow pigment
• Found in orange vegetables
• Accumulates in epidermal cells and
fatty tissues of the dermis
• Can be converted to vitamin A
Melanin
• Yellow-brown or black pigment
• Produced by melanocytes in stratum
germinativum
• Stored in transport vesicles
(melanosomes)
• Transferred to keratinocytes
Function of Melanocytes
• Melanin protects skin from sun damage
• Ultraviolet (UV) radiation:
– causes DNA mutations and burns which
lead to cancer and wrinkles
Melanocytes
Figure 5–5
Melanocytes
• Skin color depends on melanin
production, not number of
melanocytes
Capillaries and Skin Color
• Oxygenated red blood contributes to
skin color:
– blood vessels dilate from heat, skin
reddens
– blood flow decreases, skin pales
Cyanosis
• Bluish skin tint
• Caused by severe reduction in blood
flow or oxygenation
Illness and Skin Color
• Jaundice:
– buildup of bile produced by liver
– yellow color
• Addison’s disease:
– and other diseases of pituitary gland
– skin darkening
Illness and Skin Color
• Vitiglio:
– loss of melanocytes
– loss of color
Vitamin D
• Epidermal cells produce cholecalciferol
(vitamin D3):
– in the presence of UV radiation
• Liver and kidneys convert vitamin D
into calcitriol:
– to aid absorption of calcium and
phosphorus
Vitamin D
• Insufficient vitamin D:
– can cause rickets
Epidermal Growth Factor (EGF)
• Is a powerful peptide growth factor
• Is produced by glands (salivary and
duodenum)
• Is used in laboratories to grow skin
grafts
Functions of EGF
•
•
•
•
Promotes division of germinative cells
Accelerates keratin production
Stimulates epidermal repair
Stimulates glandular secretion
KEY CONCEPT
• The epidermis:
– is a multilayered, flexible, self-repairing
barrier
– prevents fluid loss
– protects from UV radiation
– produces vitamin D3
– resists abrasion, chemicals, and pathogens
What are the structures and
functions of the dermis?
The Dermis
• Is located between epidermis and
subcutaneous layer
• Anchors epidermal accessory structures
(hair follicles, sweat glands)
• Has 2 components:
– outer papillary layer
– deep reticular layer
The Papillary Layer
• Consists of areolar tissue
• Contains smaller capillaries,
lymphatics, and sensory neurons
• Has dermal papillae projecting
between epidermal ridges
The Reticular Layer
• Consists of dense irregular connective
tissue
• Contains larger blood vessels, lymph
vessels, and nerve fibers
• Contains collagen and elastic fibers
• Contains connective tissue proper
Dermatitis
• An inflammation of the papillary layer
• Caused by infection, radiation,
mechanical irritation, or chemicals
(e.g., poison ivy)
• Characterized by itch or pain
Characteristics of Dermis
• Strong, due to collagen fibers
• Elastic, due to elastic fibers
• Flexible (skin turgor)
Skin Damage
• Sagging and wrinkles (reduced skin
elasticity) are caused by:
–
–
–
–
dehydration
age
hormonal changes
UV exposure
Skin Cancer
Figure 5–6
Stretch Marks
• Thickened tissue resulting from:
– excessive stretching of skin due to:
• pregnancy
• weight gain
Lines of Cleavage
• Collagen and elastic fibers in the
dermis:
– are arranged in parallel bundles
– resist force in a specific direction
Clinical Importance
• Lines of cleavage establish important
patterns:
– a parallel cut remains shut, heals well
– a cut across (right angle) pulls open and
scars
Lines of Cleavage
Figure 5–7
Dermal Circulation
Figure 5–8
Arteries
• Cutaneous plexus:
– a network of arteries along the reticular
layer
• Papillary plexus:
– capillary network from small arteries in
papillary layer
Veins
• Venous plexus:
– capillary return deep to the papillary
plexus
• Contusion:
– damage to blood vessels resulting in
“black and blue” bruising
Nerves
• Nerve fibers in skin control:
– blood flow
– gland secretions
– sensory receptors
• Tactile disks monitor Merkel cells
KEY CONCEPT
• The dermis:
– provides mechanical strength, flexibility
and protection
– is highly vascularized
– contains many types of sensory receptors
What are the structures
and functions of the
subcutaneous layer?
The Hypodermis
• The subcutaneous layer or hypodermis:
– lies below the integument
– stabilizes the skin
– allows separate movement
Structure of the Hypodermis
• The subcutaneous layer is:
– made of elastic areolar and adipose
tissues
– connected to the reticular layer of
integument by connective tissue fibers
Clinical Importance
• Subcutaneous layer:
– has few capillaries and no vital organs
– is the site of subcutaneous injections using
hypodermic needles
Adipose Tissue
• Deposits of subcutaneous fat:
– have distribution pattern determined by
hormones
– are reduced by cosmetic liposuction
Integumentary
Accessory Structures
• Hair, hair follicles, sebaceous glands,
sweat glands, and nails:
– are derived from embryonic epidermis
– are located in dermis
– project through the skin surface
What determines hair growth,
texture, and color?
Location of Hair
• The human body is covered with hair,
except:
–
–
–
–
palms
soles
lips
portions of external genitalia
Functions of Hair
• Protects and insulates
• Guards openings against particles and
insects
• Is sensitive to very light touch
The Hair Follicle
• Is located deep in dermis
• Produces nonliving hairs
• Is wrapped in a dense connectivetissue sheath
• Base is surrounded by sensory nerves
(root hair plexus)
Structures of Hair and Follicles
Figure 5–9a
Accessory Structures of Hair
• Arrector pili:
– involuntary smooth muscle
– causes hairs to stand up
– produces “goose bumps”
• Sebaceous glands:
– lubricate the hair
– control bacteria
Regions of the Hair
• Hair root:
– lower part of the hair
– attached to the integument
• Hair shaft:
– upper part of the hair
– not attached to the integument
Inside the Follicle
Figure 5–9b
Keratin
• As hair is produced, it is keratinized:
– medulla contains flexible soft keratin
– cortex and cuticle contain stiff hard
keratin
Hair Growth Cycle
• Growing hair:
– is firmly attached to matrix
• Club hair:
– is not growing
– is attached to an inactive follicle
Hair Growth Cycle
• New hair growth cycle:
– follicle becomes active
– produces new hair
– club hair is shed
Types of Hairs
• Vellus hairs:
– soft, fine
– cover body surface
• Terminal hairs:
– heavy, pigmented
– head and eyebrows
– other parts of body after puberty
Hair Color
• Produced by melanocytes at the hair
papilla
• Determined by genes
What are the skin glands
and secretions?
Exocrine Glands
• Sebaceous glands (oil glands):
– holocrine glands
– secrete sebum
• Sweat glands:
– merocrine glands
– watery secretions
Types of Sebaceous Glands
• Simple branched alveolar glands:
– associated with hair follicles
• Sebaceous follicles:
– discharge directly onto skin surface
Sebaceous Glands
Figure 5–10
Sebum
• Contains lipids and other ingredients
• Lubricates and protects the epidermis
• Inhibits bacteria
What are the functions
of sweat glands?
Types of Sweat Glands
• Apocrine:
– found in armpits, around nipples, and
groin
• Merocrine:
– widely distributed on body surface
– especially on palms and soles
Apocrine Sweat Gland
Figure 5–11a
Apocrine Sweat Glands
•
•
•
•
Merocrine secretions, not apocrine
Associated with hair follicles
Produce sticky, cloudy secretions
Break down and cause odors
Merocrine Sweat Glands
• Also called eccrine glands:
–
–
–
–
coiled, tubular glands
discharge directly onto skin surface
sensible perspiration
water, salts, and organic compounds
Merocrine Sweat Gland
Figure 5–11b
Functions of Merocrine Sweat
• Cools skin
• Excretes water and electrolytes
• Flushes microorganisms and harmful
chemicals from skin
Other Integumentary Glands
• Mammary glands:
– produce milk
• Ceruminous glands:
– protect the eardrum
– produce cerumen (earwax)
Homeostasis
• Thermoregulation:
– is the main function of sensible
perspiration
– works with cardiovascular system
– regulates body temperature
KEY CONCEPT
• Skin plays a major role in controlling
body temperature:
– acts as a radiator
– removes heat from dermal circulation
– works by evaporation of sensible
perspiration
What is the structure of nails,
and how do they grow?
Nail Functions
• Nails protect fingers and toes:
– made of dead cells packed with keratin
– metabolic disorders can change nail
structure
Structure of a Nail
Figure 5–12
How does injured skin
respond and repair itself?
Repair of Localized Injuries
to the Skin: Step 1
• Bleeding occurs
• Mast cells trigger
inflammatory
response
Figure 5–13 (Step 1)
Repair of Localized Injuries
to the Skin: Step 2
• A scab stabilizes
and protects the
area
Figure 5–13 (Step 2)
The Inflammatory Response
• Germinative cells migrate around the
wound
• Macrophages clean the area
• Fibroblasts and endothelial cells move
in, producing granulation tissue
Repair of Localized Injuries
to the Skin: Step 3
• Fibroblasts
produce scar
tissue
• Inflammation
decreases, clot
disintegrates
Figure 5–13 (Step 3)
Repair of Localized Injuries
to the Skin: Step 4
• Fibroblasts
strengthen scar tissue
• A raised keloid forms
PLAY
Integumentary Repair
Figure 5–13 (Step 4)
Rule of Nines
• To estimate burn
damage, surface
area is divided
into multiples of 9
Figure 5–14
What are the effects
of aging on the skin?
Effects of Aging
•
•
•
•
•
Epidermal thinning
Decreased numbers of Langerhans cells
Decreased vitamin D3 production
Decreased melanocyte activity
Decreased glandular activity (sweat
and oil glands)
Effects of Aging
•
•
•
•
•
Reduced blood supply
Decreased function of hair follicles
Reduction of elastic fibers
Decreased hormone levels
Slower repair rate
How does the
integumentary system work
with other systems?
Importance of the
Integumentary System
• Protects and interacts with all organ
systems
• Changes in skin appearance are used to
diagnose disorders in other systems
Interactions with the
Integumentary System
Figure 5–15
SUMMARY (1 of 12)
• Division of:
– integument into epidermis and dermis
– epidermis into thin skin and thick skin
SUMMARY (2 of 12)
• Layers of the epidermis:
–
–
–
–
stratum
stratum
stratum
stratum
germinosum
spinosum
lucidum
corneum
SUMMARY (3 of 12)
• Roles of epidermal ridges and dermal
papillae
SUMMARY (4 of 12)
• Functions of specialized cells:
– Langerhans cells
– Merkel cells
SUMMARY (5 of 12)
• Skin pigments:
– carotene
– melanin
SUMMARY (6 of 12)
• Metabolic functions of epidermis:
– vitamin D3
– epidermal growth factor
SUMMARY (7 of 12)
• Divisions of the dermis:
– papillary layer
– reticular layer
SUMMARY (8 of 12)
• Mobility of the dermis:
– stretch marks
– lines of cleavage
SUMMARY (9 of 12)
• Blood supply of the dermis:
– cutaneous plexus
– papillary plexus
SUMMARY (10 of 12)
• Role of the subcutaneous layer
• Structure of hair and hair follicles
SUMMARY (11 of 12)
• Glands of the skin:
– sebaceous
– sweat
– ceruminous
SUMMARY (12 of 12)
• Structure of nails
• Processes of inflammation and
regeneration
• Effects of aging on the integument