A&P- BIO 1110
Integumentary System Notes
General Characteristics:

The integumentary system includes the ___________ and its
___________________________.

What are the 3 parts to the skin?

The skin is the ____________ organ of the body.
o
Approximately 22 ft2
o
Approximately 16% of total body weight
o
0.5mm-4 mm thick

Thickest regions=

Thinnest regions=
Skin Functions:
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Thermoregulation:
o
Most important function
o
Excess heat is carried to the skin by the blood vessels.
o
Skin absorbs heat and transfers it to the surrounding air.
Protection:
o
Works the best as a barrier when it is intact- no cuts, scrapes, etc..
o
Approximately ____ layers of cells.
A&P- BIO 1110
Integumentary System Notes
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
Sense organ:
o
Sensations of touch, vibration and pain
o
Collects information from the outside world and sends it to the brain
o
What parts of the body are the most sensitive?
Secretion and absorption:
o
o

Secretion:

Secretes ____________ and _____________ through glands.

What wastes can the skin remove?
Absorption:

Taking materials into the body through the skin.

Most absorbed- ____________________ vitamins (A, D, E, K)

Some toxins are absorbed- rubbing alcohol, acetone, chlorine
Vitamin D production:
o
When exposed to sunlight, the precursor becomes vitamin D because the
light energy transforms its shapes.
o
It takes hours of sun exposure to produce the amount of vitamin D in a glass
of milk. Is it worth it?
Epidermis: Outer Layer of Skin





What is the function of the epidermis?

Cells of the epidermis:
o
Keratinocytes
These cells make up _____ % of the epidermis

What is keratin?
A&P- BIO 1110
Integumentary System Notes

Most keratinocytes are _______

They don’t really become flattened until they reach the top layers
due to pressures from above and below as the cells move up the
epidermis.
o

What is keratinization?

Happens as cells move up through the epidermis

This is what eventually kills the keratinocytes
Melanocytes
What is the function of melanocytes?

Produce melanin-

It is produced by _______________ feedback. The more exposurethe more melanin produced- which means the more the skin can be
exposed to the sun.

We all have the same # of melanocytes per square inch of the skin.
Our melanocytes just produce a varying amount of melanin.
o
o
Langerhans cells
What is the function of Langerhans cells?

These are ________________________- engulf and destroy
Merkel cells
Function to gather information (touch, temperature, vibration, and
pain) and send it to the brain to be interpreted.
o
Melanocytes, Langerhans cells and Merkel cells account for the remaining
_____% of the epidermis.

Layers of the epidermis:
o
Stratum Basale
A&P- BIO 1110
Integumentary System Notes

Lies above the dermis and blood vessels in the dermis supply this
layer with blood (by diffusion)

Here is where _________________________takes place,
producing new skin cells and pushing older cells toward the surface.
o
Stratum Spinosum- superficial to the _______________________.


Cells have small projections “spiny” that help lock the cells together
like velcro.
o
Stratum Granulosum- superficial to the _________________________.


Cells are starting to look more squamous because of pressure from
the cells above and below.

Layer where _______________________ starts and cells produce
keratin in large quantities.

Can see granules of keratin in the cells.

The transition layer between __________________ and
__________ cells.
o
Stratum Lucidum- superficial to the ____________________________.

o

Only found on the ____________________________________.

Shock absorbers
Stratum Corneum- the most superficial layer of the epidermis


Spines start to break off which causes the cells to fall off

Waterproofs the skin

Takes ___________________ for cells to reach this layer from the
stratum basale.