Transcript File - Anatomy & Physiology

ANATOMY & PHYSIOLOGY
UNIT 5:INTEGUMENTARY SYSTEM
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Integumentary System
Functions (pg. 61)
• Two or more kinds of tissues grouped together and
performing specialized functions constitutes an organ.
•The integumentary system consists of a major organ,
skin, and many epidermal derivatives (accessory
structures) which include hair follicles, sebaceous
glands, sweat glands, and nails.
•Functions of the skin include protection, excretion,
regulation of body temperature, sensory reception,
immunity, synthesis of Vitamin D, and blood reservoir.
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Skin and Its Functions
 Protection:
Physical barrier
a. From water loss
b. From injury
c. From chemicals and microorganisms
Chemical barrier
a. ph of 5 – 6
b. Prohibits microbial growth
Biological barrier
a. Langerhan’s cells (epidermis)
b. Macrophages and mast cells (dermis)
 Excretion:
Minimal, most through kidneys! (urea and uric acid)
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Skin and Its Functions
 Regulation of body temperature
recall negative feedback mechanism
 Cutaneous Sensation
Light touch detection = tactile (Meissner’s) corpuscles
a. egg-shaped
b. Located in dermal papillae
c. populate areas in the fingertips, palms, soles, eyelids, tip
of the tongue, nipples, clitoris, and tip of penis
Pressure detection = lamellated (Pacinian) corpuscles
a. Onion-shaped
b. located in deep dermis and subcutaneous regions
 Vitamin D synthesis:
UV rays in sunlight activate its synthesis
Vitamin D is required for bone homeostasis
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Skin and Its Functions
 Blood Reservoir:
The dermis houses about 10% of the body’s blood vessels
Skin only requires 1 – 2% of the body’s blood
 Immunity:
Langerhan’s cells (dendritic cells)
interact with T-helper cells in immune responses
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Structure of Skin (pg. 63)
• Epidermis - outermost layer
(epithelial tissue)
• Dermis - middle layer
(connective tissue)
• Subcutaneous layer/ Hypodermis
– innermost layer
(adipose tissue)
Stratified
squamous
epithelium
Dense irregular
connective
tissue
Adipose tissue
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Epidermis
There are five (5) layers of the epidermis:
• Stratum corneum – outermost layer;
dead epithelial cells filled with the protein
keratin; accounts for ¾ of epidermal
thickness
• Stratum lucidum –translucent layer
separating s. corneum & s. granulosum
(extra layer only in thick skin – palms,
soles)
• Stratum granulosum – 3-5 layers of
flattened granular cells filled with keratin
• Stratum spinosum - many layers of
“spikey” cells w/ large nuclei
• Stratum basale – innermost layer with
singe row of mitosing cuboidal cells &
melanocytes (directly above basement
membrane)
**Together the S.spinosum and S.basale
make up the stratum germinativum
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9
Skin Color of Epidermis
Pigment = melanin
a) determines skin color
b) produced by melanocytes in s. basale *same number of
melanocytes…different amount of melanin produced by
them that determines skin color
 Different factors determine skin color
 Genetic Factors
• DNA varying amounts of
melanin (Albinos cannot form
melanin)
• excess secretion of ACTH in
pituitary gland
 Environmental Factors
• Sunlight
• UV light from sunlamps
• X-rays
 Physiological Factors
• Carotene may accumulate in
s. corneum = orange
• Hemoglobin in dermal blood vessels
= pink
• Lack of oxygenated hemoglobin =
blue (cyanosis)
• Inability to breakdown Hemoglobin
(liver problem) = yellow
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Dermis
 inner layer of skin; binds epidermis to underlying tissues
Structure:
A. two distinct layers
1) papillary layer
2) reticular layer
B. houses epidermal derivatives
or accessory structures
Epidermis
Hair shaft
Sweat gland pore
Sweat
Stratum corneum
Stratum basale
Capillary
Dermal papilla
Basement membrane
Ex. nails, hair follicles and
skin glands
Dermis
Subcutaneous
layer
 Functions:
A. nourishment of epidermis
B. provides strength/flexibility
Tactile (Meissner’s) corpuscle
Sebaceous gland
Arrector pili muscle
Sweat gland duct
Lamellated (Pacinian) corpuscle
Hair follicle
Sweat gland
Nerve cell process
Adipose tissue
Blood vessels
Muscle layer
(a)
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Dermis
Two layers of the dermis:
1) Papillary layer (20%)
a. superficial = below epidermis
b. loose areolar CT
c. dermal papillae here
form fingerprints in thick skin
d. Meissner’s corpuscles
- light touch receptor Papillary layer
2) Reticular layer (80%)
Reticular layer
a. collagen/elastic/reticular
fibers = strength & resiliency
b. point of attachment for many
muscles
c. Lamellated (Pacinian) corpuscles
– deep pressure receptors
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Hypodermis
• AKA subcutaneous layer or superficial fascia
• Area rich in fat and areolar tissues
• Fat content of hypodermis varies among individuals
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Accessory Structures of the Skin
(pg. 65)
 Hair
 Nails
 Glands
1. Sweat/Sudoriferous Glands
-Eccrine
-Apocrine
2. Sebaceous Glands
3. Ceruminous Glands
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Hair
 Growth of hair begins when cells of the epidermis spread
down into the dermis, forming a small tube, the follicle
 Part of the hair, namely the root, lies hidden in the follicle (cells are





mitotically active)
Visible part of the hair is the shaft (dead cells)
Inner core of the hair is known as the medulla…superficial part of
the hair is known as the cortex…covering layer is called the cuticle
Layers of keratinized cells make up cortex containing melanin
(brown or black hair) *unique type of melanin containing iron
responsible for red* *gray or white hair results from a decrease in
melanin content*
Straight hair= round, cylindrical shaft…curly hair=flat shaft that’s
not as strong
Two or more sebaceous glands secrete sebum into each hair follicle
lubricating hair to keep it from becoming dry, brittle, and damaged
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Hair
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Nails
 Heavily keratinized epidermal cells compose
fingernails and toenails
 Nails grow by mitosis of cells in stratum
germinativum beneath the lunula
 Parts of the nail
 Visible part= nail body
 Rest of the nail (lies in a groove hidden by a fold of
skin called the cuticle) = nail root
 Part of nail body nearest root (crescent-shaped
white area *lacks melanin*)= lunula
 Epidermis under nails (abundant blood vessels so
appears pink) = nail bed
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Nails
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Glands
 Skin glands:
1. Sebaceous glands
 Secrete oil for the hair and skin to keep it soft
 Prevents excess water loss from epidermis
 Simple, branched holocrine glands located within
the dermis
 NOT found in palms and soles
 Almost always associated with a hair follicle
 Hypersecretion of sebum causes acne
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Glands
 Skin glands: cont
2. Sweat/Sudoriferous glands
a. Merocrine (eccrine) glands
 Most numerous and widespread sweat gland in the body
 Small, and distributed all over the body (except lips, ear
canal, penis, and nail beds)
 Simple, coiled, tubular glands *coil in deep dermis; duct in
dermis; pore at surface*
 Produce a transparent watery liquid rich in salts,
ammonia, uric acid, urea, and other wastes
 Help body maintain a constant core temperature
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Glands
 Skin glands: cont
2. Sweat/Sudoriferous glands
b. Apocrine glands
 Located deep in the subcutaneous layer of the skin in the
armpit, the areola of the breasts, and the skin areas around the
anus
 Connected with hair follicles
 Enlarge and begin to function at puberty and continue
throughout your lifetime
 Secrete a thicker and colored secretion that may contain an
odor
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Glands
 Skin glands:
3. Ceruminous glands


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

Modified apocrine sweat gland
Located in the external ear canal
Mixed secretion of sebaceous and ceruminous glands
form a brown waxy substance called cerumen, or wax
Used to protect the ear from dehydration
When cerumen accumulates, it can harden and cause a
blockage in the ear, resulting in the loss of hearing
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Types of Glands
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Healing of Wounds and Burns
(pg. 67)
 A. Cuts
1. Epidermal cuts are closed by increased cell division in the
stratum basale
2. Deep cuts involve blood vessel damage resulting in:
a. inflammation
b. blood clotting
c. scab formation
d. fibroblast infiltration
e. scab falls off
f. scar may or may not form
 B. Burns
1. superficial partial- thickness burns (1st degree)
a. epidermis only
b. reddening due to increased blood flow
c. mild pain
d. common in sunburn
e. heals in a few days to 2 weeks
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Healing of Wounds and Burns
 B. Burns (cont)
2. Deep partial-thickness burns (2nd degree)
a. epidermis & some dermal damage
b. reddening and blistering (blood vessel damage)
c. moderate pain
d. common to physical contact w/ hot objects
e. heals in 2-6 weeks w/0 scars unless infected
3. Full-thickness burns (3rd degree)
a. epid., derm., and subcutaneal damage
b. dry, leathery tissue w/ red or black color
c. severe pain
d. caused by prolonged heat or chemical contact
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Healing of Wounds and Burns
 B. Burns…cont
3. Full-thickness burns (3rd degree)
e. healing rarely occurs due to lack of surviving skin
cells; grafts needed; usually extensive scarring
f. autograft – transplant from undamaged area of self
g. homograft – temporary transplant from cadaver
4. Body surface affected
a. estimated by “rule of nines”
*9% of total skin area covers head and each upper
extremity (including front and back surfaces); 18%
covers: front of trunk, back of trunk, each lower
extremity including front and back surfaces*
b. important for determining treatment/prognosis
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Scab
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Rule of Nines
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Regulation of Body Temperature
(pg. 69)
 Regulation of body temperature is vitally important because even slight
shifts can disrupt metabolic reactions
* Heat production is mostly a by-product of cellular respiration
* Normal body temp. is 37°C or 98.6°F
* Controlled by the brain…skin regulates body temperature
 Dermal Blood Flow
controlled by regulating heat loss/retention within body
a. vasodilation – increases dermal blood flow = increases heat loss
b. vasoconstriction – decreases dbf = decreases heat loss
 Four methods of heat loss
a. radiation – most heat loss; infrared heat rays move from
area of high heat (blood) to low heat (environ)
b. conduction – less heat loss; heat moves by physical contact
c. convection – heat loss to surrounding air; incr. as air moves
d. evaporation – heat loss varies; lose heat by sweat
evaporating on skin
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Regulation of Body Temperature
 Low Body Temperature
 Heat must be produced
 Flow of blood to skin is reduced—vasoconstriction (decreasing radiation)
 Reduce secretion of perspiration by sweat glands (decrease evaporation
and convection)
 Shivering occurs in skeletal muscles and those contractions produce heat
 High Body Temperature
 Heat must be released
 Flow of blood to skin is increased—vasodilation (increasing radiation)
 Sweat glands produce perspiration (increasing convection and
evaporation)
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Regulation of Body Temperature
 Problems in Temperature Regulation
1. Hyperthermia = elevated body temperature
 Dangerous if core body temperature rises above 104°F
 Can be caused by a heat stroke, drugs, infection, or damage to
hypothalamus
2. Hypothermia = low body temperature
 Dangerous if core body temperature drops below 95°F (mild),
below 90°F (moderate) and below 82°F (severe)
 Can be caused by alcohol consumption, water immersion,
dehydration, homelessness
 Limbs can withstand 65°F because they contain no vital
organs
 Can be intentional during some surgical procedures
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Regulation of Body
Temperature
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Control center
Hypothalamus
detects the deviation
from the set point and
signals effector organs.
Receptors
Thermoreceptors
send signals to the
control center.
Effectors
Dermal blood vessels
dilate and sweat glands
secrete.
Stimulus
Body temperature rises
above normal.
Response
Body heat is
lost to surroundings,
temperature drops toward
normal.
too high
Normal body
temperature
37°C (98.6°F)
too low
Stimulus
Body temperature
drops below normal.
Receptors
Thermoreceptors
send signals to the
control center.
Response
Body heat is conserved,
temperature rises toward normal.
Effectors
Dermal blood
vessels constrict
and sweat glands
remain inactive.
Control center
Hypothalamus
detects the deviation
from the set point and
signals effector organs.
Effectors
Dermal blood
vessels constrict
and sweat glands
remain inactive.
If body temperature
continues to drop,
control center signals
muscles to contract
involuntarily.
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Skin Cancer
(p.70)
• 2 out of 5 cancers are skin cancers
• Caused by damage to DNA usually through
chemicals or radiation
• Types of tumors:
• Benign: do not spread
• Malignant: cancerous; metastasize (move) to
other parts of body
• UV radiation is the main cause of skin cancer
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Skin Cancer Types
• Basal Cell Carcinoma
• Most common, least malignant skin
cancer
• Usually occur on face
• Arise from stratum basale
• Seldom metastasize—treated surgically
by removal or radiation
• 99% cure rate if caught early
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Skin Cancer Types
• Squamous Cell Carcinoma
• 2nd most common—most
common in people with darker
skin
• Arise from stratum spinosum
• Metastasizes to lymph nodes if
left untreated
• 1500-2000 deaths per year in
US
• Early removal allows for a good
prognosis
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Skin Cancer Types
• Malignant Melanoma
• Least common but most deadly
• Originates in melanocytes
• Metastasizes rapidly to lymph and blood
vessels
• Appear as brown or black irregular
patch occurring suddenly
• A change in an existing wart or mole
may indicate melanoma
• Surgical removal of melanoma and
surrounding areas and chemotherapy
required
• Due to brief intense exposures
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Skin Cancer
ABCDE’s of Melanoma:
Asymmetry: Half of the mole does not match the
other half.
Border Irregularity: The mole’s border is irregular
or jagged.
Colors: The mole has a variety of colors. It has shades
of brown, tan, black, red, or blue.
Diameter: The mole is 6 millimeters wide (about the
width of a pencil eraser) or larger.
Evolution: The mole has either changed color or
grown in width or height. Or it is bleeding, crusting,
or itchy.
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Skin Disorders (pg.71)
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•
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•
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•
•
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•
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Bedsores: deficiency of circulation to a portion of the skin
Hives: red, itchy bumps resulting from an allergic reaction
Warts: skin-colored tumors caused by a virus
Moles: slow-growing, pigmented tumors
Alopecia: loss of hair
Callus: thickened area of skin
Eczema: inflammation causing red, itchy, scaling skin; may involve
sebaceous glands
Impetigo: contagious infection in which pustules rupture and form a
yellow crust
Psoriasis: reddish, raised scaly patches on scalp, knees, or elbows
Dandruff: excessive shedding of epidermal cells of the scalp
Fever blister: blisters on lips caused by Herpes simplex
Athlete’s foot: itching, flaking skin between toes due to a fungus
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Skin Disorders Cont.
• Boil: bacterial infection of a hair follicle, sebaceous gland, and
surrounding tissues
• Dermatitis: non-specific inflammation of skin; can be caused by
reaction to product or stress
• Acne Vulgaris: disorder of plugged sebaceous glands which then fill
with leukocytes producing blackheads, cysts, pimples, and scarring
• Ringworm: highly contagious fungal infection with raised, itchy
circular patches with crust
• Shingles: viral infection of nerve endings; aka herpes zoster
• Chickenpox: viral infection causing itchy blisters all over body; aka
varicella zoster…a type of herpes
• Genital herpes: blisters in genital area spread through sexual contact;
can be passed to newborn during vaginal delivery
• Scabies: severe itching caused by mites burrowing in skin, laying eggs
and those eggs hatching
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Lifespan Changes
• Skin becomes scaly
• Age spots appear
• Epidermis thins
• Dermis becomes reduced
• Loss of fat
• Wrinkling
• Sagging
• Sebaceous glands secrete
less oil
• Melanin production slows
• Hair thins
• Number of hair follicles
decreases
• Nail growth becomes impaired
• Sensory receptors decline
• Body temperature unable to be
controlled
• Diminished ability to activate
Vitamin D
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