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CHAPTER 5 –
THE INTEGUMENTARY SYSTEM
INTEGUMENTARY SYSTEM

2 Parts:
1) Skin
2) Skin derivatives
-
Sweat glands
Oil glands
Hair
Nails
FUN FACTS

One of the largest & heaviest organs
- between 9-11 lbs
Covers between 13 & 45 sq. ft.
 About 7% of body weight in the average adult
 Thickness varies (1.5 – 4.0 mm)

- Palms & soles of feet much thicker than eyelids
SKIN STRUCTURE

Skin is composed of 3 different layers:
1) Epidermis
- outermost protective shield of the body
Epidermis
2) Dermis
- middle layer; makes up bulk of skin
*Hypodermis
- not technically part of the skin
- mostly adipose tissue; anchors skin to muscles
Hypodermis
EPIDERMIS

Epidermis is composed of several different cells:
1) Keratinocytes
- produce keratin (hardens/waterproofs the skin)
- help give epidermis its protective properties
2) Merkel cells
- touch receptors
3) Melanocytes
- made in deepest layer of epidermis
- produce melanin (skin color, amt. produced depends
on genetics & UV exposure, protection against UV rays)
EPIDERMIS

Broken down into 5 smaller layers
- From most superficial to most deep:
1) Stratum corneum
2) Stratum lucidum
3) Stratum granulosum
4) Stratum spinosum
5) Stratum basale
EPIDERMIS

Broken down into 5 smaller layers
- From most superficial to most deep:
1) Stratum corneum
- 20-30 rows of dead keratinized cells
- 75% of the epidermal thickness
- protects from abrasion
- waterproofs
- barrier against biological, chemical,
& physical assaults
EPIDERMIS

Broken down into 5 smaller layers
- From most superficial to most deep:
2) Stratum lucidum
- only found in thickest skin
- thin, transparent band
EPIDERMIS

Broken down into 5 smaller layers
- From most superficial to most deep:
3) Stratum granulosum
- cells fill with keratin in this layer
- keratin appears as granules
- cells become flattened here
EPIDERMIS

Broken down into 5 smaller layers
- From most superficial to most deep:
4) Stratum spinosum
- cells appear spiked
- cells filled with melanin
EPIDERMIS

Broken down into 5 smaller layers
- From most superficial to most deep:
5) Stratum basale
- deepest layer of epidermis
- firmly attached to dermis
- single row of cells
- constantly undergo rapid division
- takes 24-45 days for cells to
make it from here to surface
EPIDERMIS
CHAPTER 5 –
THE INTEGUMENTARY SYSTEM
DERMIS
Considered “true skin”
 Found just below the epidermis.
 This layer contains:

- Pain receptors
- Touch receptors
- Blood vessels
- Oil & Sweat Glands
DERMIS
Made of strong, flexible connective tissue
 Same as animal hides used to make leather
 Divided into 2 layers:

1) Papillary layer
- aerolar connective tissue
- collagen & elastic fibers
- capillary loops from blood vessels in the reticular layer
- Meissner’s corpuscles (fine touch receptors)
- free nerve endings (pain receptors)
DERMIS
Made of strong, flexible connective tissue
 Same as animal hides used to make leather
 Divided into 2 layers:

2) Reticular layer
- about 80% of the thickness of dermis
- collagen fibers provide strength & resiliency
- elastic fibers provide strength/recoil properties
- include cleavage (tension) lines
DERMIS – SKIN MARKINGS
Friction Ridges:
- located at top of papillary layer
- primarily on the palms of hands &
soles of feet
- increase friction & enhance gripping
ability of fingers & feet
- patterns are genetically determined
& unique
- form fingerprints
Friction ridges
Sweat glands
DERMIS – SKIN MARKINGS
Cleavage Lines:
- collagen fibers are arranged in bundles
- give the skin strength & resiliency
- give the skin strength & resiliency
- prevent jabs & scrapes from penetrating dermis
-- externally
invisible
prevent jabs
& scrapes from penetrating dermis
- used by surgeons; incisions made parallel to the
- externally
lines healinvisible
more readily & gape less
- used by surgeons; incisions made parallel to the
lines heal more readily & gape less
CHAPTER 5 –
THE INTEGUMENTARY SYSTEM
SKIN COLOR DETERMINANTS

Melanin
- yellow to reddish-brown to black
- produced by melanocytes then migrates to epidermal cells
- “pigment shield” that protects nuclei of epidermal cells
- Freckles = localized accumulations of melanin

Carotene
- yellow to orange pigment…from some vegetables
- most obvious in the palms & soles
SKIN COLOR DETERMINANTS

Hemoglobin
- red coloring…blood cells in capillaries near skin’s surface
- oxygen content affects degree of “redness”
- responsible for pinkish hue of skin
SKIN COLOR – WHAT DOES IT MEAN??

Cyanosis :
- skin appears bluish
- means blood is poorly oxygenated
- can be a sign of heart failure or respiratory trouble

Erythema:
- skin has redness
- fever, embarrassment, hypertension, inflammation
SKIN COLOR – WHAT DOES IT MEAN??

Pallor:
- skin becomes pale; ashen
- fear, anger, emotional stress, anemia, low BP

Jaundice:
- skin has a yellowish tint
- signifies liver disorder
SKIN COLOR – WHAT DOES IT MEAN??

Bronzing:
- skin has bronze, slightly metallic tint
- signifies Addison’s disease (adrenal glands making too
little steroid hormone)

Black & blue marks:
- form when blood escapes circulation & clots under skin
- known as a “hematoma” or bruise
CHAPTER 5 –
THE INTEGUMENTARY SYSTEM
SKIN DERIVATIVES

Skin derivatives
1) Hair
2) Nails
3) Tooth enamel
4) Glands
SKIN DERIVATIVES

Sweat Glands
- Formally known as Sudoriferous glands
- Two main types of sudoriferous glands:
1) Eccrine sweat glands
- abundant on palms, soles, & forehead
- sweat = 99% H2O, NaCl, Vit C, antibodies, dermicidin,
wastes
- function in thermoregulation…cooling
SKIN DERIVATIVES

Sweat Glands
- Formally known as Sudoriferous glands
- Two main types of sudoriferous glands:
2) Apocrine sweat glands
- mostly only found in axillary (armpit) region
- secretions composed of sweat, fats, & proteins
- odorless secretions; when bacteria on skin break down its
organic molecules, they create unpleasant “body odor”
- functional from puberty onward
*Ceruminous glands = specialized apocrine glands that secrete a
bitter, waxy product in ear canals…believed to deter insects
SKIN DERIVATIVES

Oil Glands
- Formally known as Sebaceous glands
- Widely distributed; not found on palms or soles
- Become active at puberty (often associated with
acne); stimulated by hormones
- Secrete oily substance called sebum
- Function is to soften & lubricate skin
- Most develop from hair follicles
SKIN DERIVATIVES

Hair
- Functions:
1) Alerts body to presence of insects on skin
2) Guards scalp against physical trauma, heat loss, &
sunlight
- Structure:
1) Consists of dead keratinized cells
2) Melanin gives hair its color
*Gray/white hair = decreased melanin production;
increased air bubbles in hair
SKIN DERIVATIVES

Hair follicle
- Attached to arrector pili muscle
(responsible for goose bumps)
- Oil glands coat hair…keep it from
becoming brittle
SKIN DERIVATIVES

Hair thinning & baldness:
- Hair follicles have limited number of cycles
- Grows fastest from teen years to your 40s
Alopecia
- Hair thinning in both males/females after 40
True baldness
- Genetically determined & more common in men
SKIN DERIVATIVES

Nails
- Extension of the epidermis @ ends of fingers/toes
- Lots of extra keratin
- Colorless due to lack of melanin
CHAPTER 5 –
THE INTEGUMENTARY SYSTEM
FUNCTION OF INTEGUMENTARY SYSTEM
1) Protection of deeper tissues using:
a) Mechanical barriers
- continuity of skin & hardness of keratinized cells
- prevent excess water from moving in or out of body
- prevent chemicals, infectious agents from entering body
b) Chemical barriers
- low pH secretions create an “acid mantle”
- slows reproduction of bacteria on the skin
- melanin = chemical pigment preventing UV damage
FUNCTION OF INTEGUMENTARY SYSTEM
2) Regulation of body temperature:
- as long as external temp remains lower than body temp,
skin surface loses heat to the air & other cooler objects
At normal body temp, body loses 500ml of H2O per day
- called insensible perspiration…routine & unnoticeable
On hot days, body can lose up to 12L (3 gal) of H2O
- called sensible perspiration
- evaporation of sweat cools the body
On cold days, dermal blood vessels constrict
- causes blood to bypass upper dermis & reduces temp loss
FUNCTION OF INTEGUMENTARY SYSTEM
3) Cutaneous sensations:
- Meissner’s corpuscles = fine touch receptors
- Pacinian corpuscles = deep pressure receptors
- free nerve endings = pain receptors
4) Metabolic functions:
- synthesis of Vitamin D
- breaks down many cancer-causing chemicals that may
penetrate the epidermis
FUNCTION OF INTEGUMENTARY SYSTEM
5) Blood reservoir:
- very extensive network of blood vessels in the dermis
- holds up to 5% of the body’s blood volume
6) Excretion:
- sweat contains nitrogen-containing wastes
- important avenue for water & salt loss
CHAPTER 5 –
THE INTEGUMENTARY SYSTEM
SKIN CONDITIONS - CANCER

Skin Cancer
- one in five Americans will develop skin cancer
**Cancer = abnormal mass of cells; uncontrolled growth
1) Benign
- Does not spread
2) Malignant
- Can metastasize (move) to other body parts
SKIN CONDITIONS - CANCER

Causes of Skin Cancer
- UV rays damage DNA bases; appears to disable the p53
gene (tumor suppressor gene)

Natural defenses
- Sunburned skin accelerates production of Fas (protein
causing genetically damaged cells to commit suicide)
- Fas causes cells to die before they mutate
**Newly developed lotion claims to fix damaged DNA before
cells develop into cancer**
SKIN CONDITIONS - CANCER

Skin Cancer Types
1) Basal cell carcinoma
-
Least malignant
Most common type
Affects stratum basale cells
Cured by surgical excision in
99% of cases
SKIN CONDITIONS - CANCER

Skin Cancer Types
2) Squamous cell carcinoma
- Involves keratinocytes of
stratum spinosum
- Most common on scalp, ears,
lower lip, & hands
- Can metastasize to lymph nodes
- Early removal & radiation
therapy = good chance of survival
SKIN CONDITIONS - CANCER

Skin Cancer Types
3) Malignant melanoma
- Most deadly
- Cancer of melanocytes
- Metastasizes very rapidly
to lymph nodes
- Resistant to chemotherapy
- Treated by wide surgical excision
& immunotherapy
SKIN CONDITIONS - CANCER

“ABCD” Rule
- Use to detect possible cancerous moles
“A” = Asymmetry
- the two sides of pigmented area do not match
“B” = Border
- Jagged/indented borders
“C” = Color
- Multiple colors in pigmented area
“D” = Diameter
- Larger than 6mm in diameter
SKIN CONDITIONS - BURNS

Burns
- Tissue damage caused by heat, chemicals, UV rays,
or electricity
- Associated dangers:
1) Dehydration & electrolyte imbalances (initial concern)
2) Infection can cause death
SKIN CONDITIONS - BURNS

Severity of Burns
1) First degree
- Only affects epidermis
- Localized redness, swelling, & pain
2) Second degree
Partial Thickness
- Affects epidermis & upper dermis
- Skin is red w/ blisters
3) Third degree
- Destruction of all skin layers
- Skin is gray-white or black
- No pain; nerve endings destroyed
Full Thickness
SKIN CONDITIONS - BURNS
2nd Degree
1st Degree
3rd Degree
SKIN CONDITIONS - BURNS

Rule of Nines
- Used by doctors to estimate extent of burns & the
volume of fluid loss from burns
- Body is divided into 11 equal segments
- Each is approximately 9% of body
SKIN GUN…
OTHER SKIN CONDITIONS

Contact dermatitis
- Exposure to chemicals…causes allergic reaction
OTHER SKIN CONDITIONS

Decubitus ulcer (bed sore)
- Caused by lack of blood supply
OTHER SKIN CONDITIONS

Psoriasis
- Cause is unknown…possible autoimmune disorder
- Often triggered by trauma, infection, or stress
OTHER SKIN CONDITIONS

Infections
1) Cold sores
- Caused by herpes simplex virus
OTHER SKIN CONDITIONS

Infections
2) Athlete’s Foot
- Caused by fungal infection
OTHER SKIN CONDITIONS

Infections
3) Impetigo
- Caused by bacterial infection
OTHER SKIN CONDITIONS

Infections
See “World’s Largest Zit” on YouTube!! 
4) Boils & Carbuncles
- Caused by bacterial infection
CHAPTER 5 –
THE INTEGUMENTARY SYSTEM
DEVELOPMENTAL ASPECTS

Adolescent to Adulthood:
- sebaceous (oil) gland activity increases
- effects of cumulative skin abuse (sun damage, etc) begin
to show after age 30
- scaling & dermatitis become more common
DEVELOPMENTAL ASPECTS

Old Age:
- epidermal replacement slows
- skin becomes thin, dry, & itchy
- hypodermis & skin elasticity decreases leading to cold
intolerance & wrinkles
- increased risk of cancer due to decreased melanin
production