Warmup 1/11/16
What do you already know about skin? Summarize as best as you can
To learn the structure and function of skin
pp 513: 1, 2, 3, 4

Notes on the Integumentary System
What is this system? This is skin.
A few facts about skin:
- Your skin covers about 2,800 in 2
- On average, your skin is 1/8 of an inch thick
- Your skin is your largest organ

Notes on the Integumentary System
Purpose
What’s the purpose of skin? It has a few:
- Protection
Skin protects your body from outside contaminants like germs, dirt, and disease.
- Sensation
Skin alerts our bodies to outside threats or obstacles we need to be aware of.
- Heat Control
Our sweat glands help regulate temperature.
In cold weather, it helps keep heat in.

Notes on the Integumentary System
- Excretion
Sweat carries contaminants out along with heat. You can literally “sweat out” toxins.
- Hormone Manufacture
The skin manufactures a few hormones that help regulate a few bodily function.
- Absorption
Skin can absorb substances directly, whether for good or bad. Water and oxygen primarily.

Notes on the Integumentary System
Layers
Epidermis
The epidermis is the uppermost layers of the skin. The upper levels here are made of dead cells that continually fall off.
Stratum corneum
The deepest layer, the stratum germinativum, carries on cell division and creates new skin.

Notes on the Integumentary System
Dermis
The dermis is made of connecting tissues, blood vessels, nerve endings, sweat glands, hair follicles, and oil glands.
If you cut yourself and bleed, you’ve cut down to the dermis.
Stratum corneum

Notes on the Integumentary System
Subcutaneous Tissue
This isn’t actually part of the skin. Technically, this is the tissue between the skin and the underlying muscle.
Fat is usually found in this layer to provide cushioning between skin and muscle.
Stratum corneum

Notes on the Integumentary System
Skin Diseases and Disorders
A number of things can go wrong with skin.
Acne
The oil glands – or sebaceous glands – produce oil to keep your skin from cracking. This oil secretes into the hair follicles where it’s pushed to the surface.
As skin sheds, some of it can “glue together” and block the pore. This causes oil to keep building up behind the pore.

Notes on the Integumentary System
As this oil buildup continues, bacteria begin to feed and the site becomes infected. As your body fights the infection, it creates pus as a waste product. This pus builds up until the skin blocking the pore gives way and the pimple bursts.

Notes on the Integumentary System
Blisters
When injured, plasma – a clear fluid often found in blood – can leak between layers of tissue, filling it with fluid. This happens mainly from friction, but can also be caused by burns or chemicals. Often this fluid drains when the blister “pops”. Blisters that fill with blood are called “blood blisters”.

Notes on the Integumentary System
Burns
Burns come in four levels of damage.
1 st degree:
If the skin gets too hot, proteins within the cells start to lose their 3-D shape. This causes damage to the cells.
Cells lose their ability to retain moisture and the nerve endings become extra sensitive. First degree burns damage the epidermis only.

Notes on the Integumentary System
2 nd Degree
In a second degree burn, the skin blisters as blood vessels are damaged. The damage here reaches as low as the papillary dermis at the root of hair follicles. Strangely enough, this is often the most painful kind of burn because nerves have been exposed and dried but not damaged.
3 rd Degree
These burns extend all the way through the dermis. They’re often painless as they’ve damaged or destroyed nerves. These burns never heal fully and may require a skin graft.

Notes on the Integumentary System
4 th Degree
These burns reach through the skin into the subcutaneous tissue and may even damage muscle or bone. At best, these burns require amputation. At worst, they can cause death.
First degree burn second degree burn
(warning! Next two images are disturbing!)

Notes on the Integumentary System
Third degree fourth degree

Notes on the Integumentary System
Warts
Warts are caused by the human papillomavirus
(HPV). Since they’re viral, they are contagious and can be caught through open or broken skin.
This virus causes a thickening of the epidermal layers and infection and enlargement of the blood vessels beneath.

Exit Question
What is the difference between the epidermis and the dermis?
a) The dermis contains fat, the epidermis doesn’t.
b) The epidermis contains fat, the dermis doesn’t.
c) The epidermis has nerves and hair follicles.
d) The dermis has nerves and hair follicles.
e) Both have nerves and hair follicles.
f) None of the above