Download Integumentary System

INTEGUMENTARY SYSTEM
Skin, Hair, Nails, Skin Glands
Skin Fact
• In 1 square inch of skin there are 4 yards of
nerve fibers, 1300 nerve cells, 100 sweat
glands, 3 million cells, and 3 yards of blood
vessels.
Brainstorm
Write and discuss with someone near you something you
know about the integumentary system.
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Integumentary System
SKIN
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Functions of the SKIN
1. The body’s 1st line of defense against germs
and pathogens
2. Insulates body
3. Stored source of energy
4. Shock-absorbing pad
5. Waterproof layer
SKIN
• Cutaneous membrane (sheet-like organ)
• Made of two layers
1. Epidermis: outer layer, thin sheet of stratified squamous
epithelium
2. Dermis: thicker, made largely of connective tissue
• Both layers are supported by a thick layer of loose
connective tissue and fat: subcutaneous tissue
EPIDERMIS:
layered epithelial cells
• Made of layers called
STRATA
• 1. Stratum germinativum:
-innermost layer,
undergoes mitosis
enabling skin to repair
itself
-new cells move upward,
near surface is replaced
with keratin (tough,
waterproof)
EPIDERMIS:
layered epithelial cells
• 2. Stratum corneum:
- outer layer of
epidermis
- keratin filled cells
are pushed to surface,
are dislodged and
flake off
Epidermis
• The epidermis contains four (thin skin) to five
major layers (thick skin):
– Stratum basale (deepest layer)
– Stratum spinosum, 8-10 layers of keratinocytes
– Stratum granulosum – thin layer where
keratinocytes become filled with keratin, flatten, and
lose their nuclei.
– Stratum lucidum is present only in thick skin
(fingertips, palms, and soles), reduces friction, clear
under microscope. Dead cells.
– Stratum corneum (most superficial)
Layers of the Epidermis
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Cells of the Epidermis
• Keratinocytes (90% of the cells) produce
keratin which is a tough fibrous protein
that provides protection
• Melanocytes: which produce the pigment
melanin that protects against damage by
ultraviolet radiation
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Cells of the Epidermis
• Langerhans cells: involved in immune
responses, arise from red bone marrow
• Merkel cells: which function in the sensation of
touch along with the adjacent tactile discs
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Types of
Cells in the
Epidermis
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Dermal-epidermal Junctions
• Area of contact
between the dermis
and epidermis
• Blisters will form here
if the junction is
damaged
DERMIS
• Deeper of the two
primary layers
• Contains nerves and
nerve endings, muscle
fibers, hair follicles,
sweat and sebaceous
glands, and blood
vessels
DERMIS
• Dermal papillae
- peg-like projections of
upper region of dermis,
part of dermal-epidermal
junction
- form grooves that make
fingerprints
Callus & Corn Examples
Calluses are generally on the soles of the feet
Corns
Corns are between the toes or on the outside of the toes.
Skin Color
• Melanocytes
– Produced by a skin pigment called MELANIN
– Melanin also produces freckles and moles
Albino – no melanin
INTEGUMENTARY SYSTEM
Part II: Appendages and
Functions of the Skin
SKIN FACTS
Fingernails grow nearly 4
times faster than toenails.
Which layer of the dermis is responsible for fingerprints?
The papillary layer is the layer of the dermis responsible for
fingerprints.
Which layer of the epidermis is the stratum where dandruff,
calluses, and corns occur?
The layer of the epidermis where dandruff, calluses and corns
occur is the stratum corneum.
What is the pigment called that gives our skin its color?
What is the cell that produces this pigment?
The pigment that gives our skin its color is melanin and the cell
that produces this pigment is a melanocyte.
HAIR
Follicles are present at
birth
Lanugo: fine, soft hair of
newborn; falls out shortly
after birth
Hair follicles: cells of
epidermal layer grow
down into dermis forming
a small tube
HAIR
Hair papilla: small capshaped cluster of cells
where hair growth begins
(nourished by dermal
blood vessels)
Hair root: hidden in
follicle
Hair shaft: visible part,
dead, keratinized
epithelial cells
HAIR
• Hair color – mostly due to melanin
• New hair will replace any lost as long as
the hair follicle remain alive
HAIR
Arrector pili muscle:
bundles of smooth
muscle that cause hairs
to “stand up”, usually
only contract when
frightened or cold
(goose bumps)
HAIR
RECEPTORS
Make it possible for skin
to act as a sense organ
1. Meissner’s corpuscle:
located close to surface,
detecting sensations of
light touch
RECEPTORS
2. Pacinian corpuscle:
located deep in dermis,
detects pressure of
skin’s surface
NAILS
Nail body: visible part
Root: hidden by a
fold of skin, cell
division occurs here
Cuticle: fold of skin
over nail root
NAILS
Lanula: crest-shaped
white area near root,
extent of growing
region
Nail bed: layer of
epithelial tissue
under the nail body,
rich in blood vessels,
appears pink
SKIN GLANDS
Sweat (sudoriferous)
glands:
1. Eccrine sweat glandsmost numerous, small and
distributed over most of
body’s surface, produces
perspiration which
eliminates
wastes(ammonia, uric
acid), helps maintain body
temperature
Functions to cool the body,
also released during stress
SKIN GLANDS
2. Apocrine sweat glands—
primarily in skin of armpit and
genitalia, secrete a milky
secretion, odor caused by
contamination and
decomposition of secretion by
skin bacteria, enlarge and
begin to function at puberty
SKIN GLANDS
Sebaceous glands:
secrete oil, ducts open
into hair follicles,
sebum is the secretion
that lubricates hair and
skin (increases during
adolescence)
A build up of oil and dirt
causes acne
The Effects of Aging on Skin
• blood flow to the
skin is reduced
• skin becomes thinner & more
transparent
• less elastin & fat causes wrinkles
• less collagen – more easily
damaged
• age spots, discoloration, gray
hairs
Skin Cancer
BASAL CELL CARCINOMA
• most frequent type of skin cancer
• begins in stratum basale and
goes into dermis
• treatment: surgery or radiation
• does not metastasize
SQUAMOUS CELL
CARCINOMA
• cells above statum basale
• can metastasize & cause death
MALIGNANT
MELANOMA
• from melanocytes in a mole
• can metastasize & cause death
Acne
• infection involving hair follicle & sebaceous gland
• also can have a significant hormonal cause
Skin Diseases
Acne Vulgaris
Psoriasis
Herpes Simplex I
(cold sores)
Eczema
Herpes Zoster
(Shingles)
Malignant Melanoma
Ringworm
Genital Herpes
Athlete’s Foot
Boils and Carbuncles
Impetigo
Basal Cell Carcinoma
Squamous Cell
Carcinoma
Alopecia
Albinism
Warts (verrucae)
Keloids
Scabies
Burns
The Integumentary
System
Burns may be caused by …
• Fire
• Hot surfaces
• UV rays
• Electric currents
• Chemicals
Treatment & Recovery
• Depends on the total amount of the body
burned & the severity of the burn
“Rule of Nines”
– used for adults
to estimate the
percentage of
the body burned
“Rule of Nines”
• must be adjusted
slightly for
children because
their proportions
are different from
adults
Classifying Burns
• Degree of burn is
decided according to
the number of skin
layers involved
• First Degree Burn – involves only the
upper epidermis
• causes reddening of the skin, minor
discomfort
• Ex.) mild sunburn
• Second Degree Burn – involves deep
epidermal layers and damages upper
dermal layers
• damages sweat glands, hair follicles,
sebaceous glands
• causes blistering, severs pain, swelling,
fluid loss, scarring
• Third Degree Burns –
complete destruction of the
epidermis and dermis,
damages the subcutaneous
tissue & sometimes muscle
and bone
• lesions are insensitive to pain
at first
• causes serious scarring,
extremely susceptible to
infection