How do I keep my
body healthy?

Components:
› Skin (aka cutaneous membrane or integument)
› Hair
› Nails

Components:
› Skin (aka cutaneous membrane or integument)
› Hair
› Nails
Fun fact:
The skin is the largest
organ in the body.
The skin of an average
adult weighs more than 9
lbs!
Functions
1. Protection
2. Thermoregulation
3. Excretion of wastes
4. Synthesis of vitamin D
1.
Protection
From mechanical and chemical damage
›


Barrier of tough, keratinized cells
Pain receptors warn body of possible damage
From pathogens
›



Unbroken surface
Acidic secretions inhibit bacterial growth
Phagocytes ingest foreign material
From UV radiation
›

Melanin absorbs UV light and prevents it from
reaching deeper layers
1.
Protection
From thermal damage
›

Pain receptors warn body of possible damage
From desiccation (drying out)
›

Keratin and other substances keep skin fairly
waterproof
2.
Thermoregulation
How does the skin help us cool down?
How does the skin help us warm up?
Thermoregulation
2.
How does the skin help us cool down?
›
›
Evaporative cooling (sweating)
Increased blood flow through skin (increases heat
loss)
How does the skin help us warm up?
› Goose bumps: arrector pili muscles contract to pull
hair upright, and add insulation to body
› Decreased blood flow through skin (reduces heat
loss)
3.
Excretion of wastes –
›
4.
The sweat glands excrete metabolic wastes (urea,
uric acid), salt, and lactic acid (in addition to
water)
Synthesis of vitamin D
› When UV light hits the skin,
modified cholesterol
molecules are converted
into vitamin D.
Turn & Talk (5 min), then share with class.
Scholar on left …
 Name the four major functions of the integumentary
system.
 Explain how the skin fights pathogens.
Scholar on the right …
 Name the three components of the integumentary
system.
 Explain how the skin allows us to thermoregulate.
The skin is
composed of two
layers:
1)
Epidermis –
made of
_______________
tissue
2) Dermismade of
_______________
tissue
The skin is
composed of two
layers:
1)
Epidermis –
made of
epithelial
tissue
2) Dermismade of dense
connective
tissue
Fun fact:
Blisters occur when
friction causes the
epidermis to pull
away from the
dermis.
Epidermis is made of epithelial tissue.
Quick Review:
What are the characteristics of epithelial tissue?
Epidermis is made of epithelial tissue.
Quick Review:
What are the characteristics of epithelial tissue?
 Form continuous sheets, have cell junctions
 Avascular
 Apical side free
 Other side attached to basement membrane
 Regeneration
Remembering these characteristics will help you
understand the structure and function of the
epidermis!
The epidermis has multiple
strata or layers.
Only the deepest layer
contains actively dividing cells
and melanocytes.
Why?
Because the deepest
layer is closest to the
blood supply.
As new cells form, older cells
are pushed towards the
surface
As the cells are pushed away
from the blood supply, they
atrophy and flatten.
The most superficial layer is
made of the dry, keratinized
membranes of skin cells.
Two main cell types in epidermis:
1) Keratinocytes
›
›
›
2)
Keratin-producing cells
Keratin is the protein that makes skin
tough and waterproof.
Most abundant cell in epidermis
Melanocytes
› Melanin-producing cells
› Melanin is the brown-black pigment that is largely
responsible for skin, hair, and eye color
› Melanin absorbs UV light to product DNA from damage
› Found only in deepest layer of epidermis

Major determinants of skin color
› Amount / type melanin
› Amount carotene (from fruits and veggies)
› Amount oxygen in blood

Adaptive significance
› Trade off between UV protection and vitamin D production
The dermis is made of what tissue?
The dermis is made of what tissue? Connective
(specifically, dense irregular)
Connective tissue cushions and binds things together.
In the skin, the connective tissue holds together lots of
different elements:
• Exocrine glands
• Hair follicles
• Nerves and sense receptors
• Blood vessels
The collagen and elastic fibers of the dermis give skin
its strength and elasticity
First degree burn:
only epidermis is
damaged.
Second degree
burn:
Damage extends
partway into
dermis.
Third degree burn:
Damage extends
all the way
through dermis.
First degree burn:
only epidermis is
damaged.
Second degree
burn:
Damage extends
partway into
dermis.
Third degree burn:
Damage extends
all the way
through dermis.
Signs: red, swollen skin
Example: most sun burns
Will heal on own
First degree burn:
only epidermis is
damaged.
Second degree
burn:
Damage extends
partway into
dermis.
Third degree burn:
Damage extends
all the way
through dermis.
Signs: red, swollen skin
Example: most sun burns
Will heal on own
Signs: blistering
Skin will heal with care
First degree burn:
only epidermis is
damaged.
Second degree
burn:
Damage extends
partway into
dermis.
Signs: red, swollen skin
Example: most sun burns
Will heal on own
Signs: blistering
Skin will heal with care
Signs: blackened or
blanched (gray-white)
Third degree burn:
skin, lack of pain due to
Damage extends
damaged nerves
all the way
Skin will not heal; grafts
through dermis.
must be done
Burned skin can no longer carry out its
functions
Turn & Talk
Quick
review:
are
the functions
of/ the
1) Protection
fromWhat
abrasion
/ chemical
damage
UV
damage / pathogens / against dessication
skin?
2) Excretion of wastes
Analyze:
Which functions are most
3) Thermoregulation
critical?
4) Synthesis of Vitamin D
Burned skin can no longer carry out its
functions
Most critically, skin can no longer
› Prevent loss of fluids and electrolytes
 Fluid loss and electrolyte imbalance can cause kidneys
to shut down and patients to go into shock due to low
blood volume.
 Happens almost immediately, unless fluids are replaced.
› Protect the body from pathogens
 Infection becomes a major concern within 2-3 days
following severe burns.

Burned skin cannot thermoregulate.
Hypothermia becomes a problem.

3rd degree burns cannot regenerate.
Scar tissue forms. Scar tissue does a poor job of
perfoming the functions of skin, and if the scar
tissue is extensive, mobility may be affected.
In a short paragraph explain how burn
classification and severity is related to the
structure and function of the skin.