The Integumentary System
CHAPTER 5
The Integumentary System
 The parts of the integument:
 Skin
 Sweat and Oil glands
 hairs
 Nails
The Integumentary System: The Skin
 The skin is pliable yet tough, allowing it to take






constant punishment from external organs.
Facts:
Covers 2.2 meters, weighs 4 to 5 kg, and accounts for
about 7% of total body weight in the average.
Thickness varies from 1.5 to 4.0 mm or more in some
areas.
Millions of dead cells rub off daily
A totally new epidermis every 25 to 45 days
The average person sheds 18kg (40lbs) of skin flakes
in a lifetime
The Skin
The Skin: Epidermis
 The epidermis is a keratinized stratified





squamous epithelium consisting of four
distinct cell types or five distinct layers.
Cells of the epidermis:
1. Keratinocyte produce keratin
2. melanocyte produce melanin
3. Langerhans’ cell are macrophages
4. Merkel cells (epidermal dendritic
cells) function as a sensory receptors
for touch
Layers of the Epidermis
 Thick skin: covers the






palms, fingertips, and
soles of the feet
Five Layers (strata) from
deep to superficial
1. stratum basale
2. stratum spinosum
3. stratum granulosum
4. stratum lucidum
5. stratum corneum
 Thin skin: covers the rest
of the body
 **stratum lucidum is
absent and the other
strata are thinner
The Skin:Dermis
 The dermis, composed
mainly of dense,
irregular connective
tissue, is well supplied
with blood vessels,
lymphatic vessels, and
nerves.
 Cutaneous receptors,
glands, and hair follicles
reside within the dermis
Layers of the dermis
 From superficial to deep:
 1. papillary layer exhibits dermal
papillae that protrude into the
epidermis above and the
epidermal ridges that produce
fingerprints.
 2. reticular layer is thicker and
the connective tissue fibers are
much more densely interwoven.
Skin Color
 Skin color reflects the amount of
pigments (melanin and carotene) in
the skin and the oxygenation level of
hemoglobin in blood
 1. Melanin is the only pigment made
in the skin.
 ranges in color from yellow, redish
brown, to black
 Stimulated by exposure to ultraviolet
radiation in sunlight and protects
the nuceli from damaging effects of
UV radiation
Homeostatic Imbalance
 1. stiae = stretch marks
 Tears in the dermis
 2. blisters = separation of dermis and epidermis
Homeostatic imbalance
 Excessive sun exposure can
 cause clumping of elastin fibers, leading to leathery
skin,
 temporarily depresses the immune system
 Alter the DNA of skin cells which may cause cancer
Homeostatic Imbalance
 1. Cyanosis = poorly oxygenated blood
Homeostatic imbalance
 Redness, or erythema = redding of skin
 Pallor or blanching
Homeostatic balance
 Jaundice or yellow cast =
Homeostatic imbalance
 Bronzing =
http://www.aldfoundation.org/materials.html
Homeostatic imbalance
 Black-and-blue marks; bruises; hematomas
Appendages of the Skin
 Skin appendages, which




derive from the epidermis,
include:
Hairs
Hair follicles
Nails
Glands
Sweat (Sudoriferous) Glands
 Found all over the body
except the nipples and the
external genitalia
 More than 2.2 million per
person
Sweat glands: Eccrine glands
 Merocirne glands
 Found over most of
the body
 Thermoregulation
 Sweat is 99% water
 Salts, Vit C.,
antibodies, metabolic
wastes and lactic acid
Sweat Gland: apocrine
 Largely confinded to the





axillary and anogenital
areas
Larger than eccrine glands
and their ducts empty
along hair follicles
Start production around
puberty
Function is unknown
Cerunminous glands
Mammary glands
Sebaceous (oil) glands
 Located all over body




except palms of hands
Sebum
Functions to softens and
lubricates the hair and skin
Prevents hair from
becoming brittle, and slows
water loss from the skin
Bacterialcidal action
Homeostatic imbalance
 Whiteheads
 Blackheads
 Acne
 Seborrhea “cradle cap”
Hairs and Hair Follicles
 Hair:
 main function is sensory protection