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Skin, Hair, and Nails-
Take notes on the bold faced paragraph’s- (you can paraphrase!)
Skin:
Your skin is the largest organ of your body!
Skin is made up of two layers of tissue, the epidermis and the dermis.
Epidermis- the cells on the top of the epidermis are dead. Thousands of these cells
rub off when you shower, shake hand, blow your nose etc.
Cells are constantly reproducing at the bottom of the epidermis. These new cells
are moved up eventually to replace the ones that rub off.
The epidermis produces a chemical called Melanin.
Melanin- a pigment that gives your skin color. Melanin increases when your skin is
exposed to ultraviolet rays of the sun.
The dermis is the layer of tissue under the epidermis.
This layer is thicker than the epidermis and contains many blood vessels, nerves, oil,
and sweat glands. Fat cells are located under the dermis. This fatty tissue
insulates the body.
When a person gains too much weight, this is where much of the extra fat is
deposited.
Function of Skin-
No need to take notes- information is in your handout!
The skin is not only the largest organ in your body, it also carries out several major
functions.
These functions include protection, sensory response, formation of vitamin D,
regulation of body temperature, and the excretion of waste.
The most important of the functions is the skins’s ability to protect against physical
and chemical injury, as well as disease.
Glands in the skin secrete fluids that damage or destroy some bacteria.
Skin also protects against water loss and it is a sensory organ. Special nerves in the
skin detect and relay information about temperature, pressure, and pain.
The final important function of the skin is its ability to form vitamin D. Without
vitamin D, your body would have a hard time absorbing calcium from the food
you eat.
Heat and Waste-
Humans unlike furry animals, have little hair to help regulate body temperature.
Hair is an adaption that usually helps control body temperature.
Blood vessels in the skin can help control body temperature. If the blood vessels expand
or dilate, blood flow increases and heat is released.
Less heat is released when the blood vessels constrict.
The dermis has about 3 million sweat glands!
These glands also help to regulate body temperature.
Waste-
The fifth function of the skin is to excrete waste. Sweat glands release water, salt, and a
protein product called urea.
If too much water or salt is released during periods of extreme heat or physical activity, you
might faint.
Injury to the Skin-
Despite the daily dose of burning, scratching, ripping, and exposure to harsh
conditions, the skin still continues to produce new cells in its outer layer, the
epidermis, and repair tears in its inner layer, the dermis.
However, if there is injury to large areas of the skin, such as burning or rubbing away
of the epidermis, there are no longer cells left that can divide to replace the lost
layer.
In severe cases of skin loss or damage, nerve endings and blood vessels in the dermis
are exposed. Water is rapidly lost from the dermis and muscle tissues. Body
tissues are exposed to bacteria and to potential infection, shock, or death.
Disease to the skin:
No need to take notes- information is in your handout!
• Although there are many skin diseases, the most common would be skin cancer.
• Cancer is the uncontrolled growth of abnormal cells in the body. Cancerous cells are also called malignant cells.
• Cells are the building blocks of living things. Cancer grows out of normal cells in the body. Normal cells multiply
when the body needs them, and die when the body doesn't need them. Cancer appears to occur when the
growth of cells in the body is out of control and cells divide too quickly. It can also occur when cells “forget”
how to die.
• If the cancer is confined to one location and has not spread, the most common goals for treatment are surgery
and cure. This is often the case with skin cancers.
• Skin cancer is divided into two major groups: nonmelanoma and melanoma.
• Basal cell carcinoma is a type of nonmelanoma skin cancer, and is the most common form of cancer in the
United States.
Treatment varies depending on the size, depth, and location of the basal cell cancer.
It will be removed using one of the following procedures:
Excision cuts the tumor out and uses stitches to place the skin back together.
Curettage and electrodesiccation scrapes away the cancer and uses electricity to kill any remaining cancer cells.
Surgery, including Mohs surgery, in which skin is cut out and immediately looked at under a microscope to check for
cancer. The process is repeated until the skin sample is free of cancer.
Cryosurgery freezes and kills the cancer cells.
Radiation may be used if the cancer has spread to organs or lymph nodes or for tumors that can't be treated with
surgery.
Skin creams with the medications imiquimod or 5-fluorouracil may be used to treat superficial basal cell carcinoma.
Prevention?
The best way to prevent skin cancer is to reduce your exposure to sunlight.
Hair and Nails!
Hair is actually a modified type of skin. Hair grows everywhere on the human body
except the palms of the hands, soles of the feet, eyelids, and lips. Hair grows more
quickly in summer than winter, and more slowly at night than during the day.
Like hair, nails are a type of modified skin — and they're not just for beauty. Nails
protect the sensitive tips of our fingers and toes. Human nails are not necessary
for living, but they do provide support for the tips of the fingers and toes, protect
them from injury, and aid in picking up small objects. Without them, we'd have a
hard time scratching an itch or untying a knot. Nails can be an indicator of a
person's general health, and illness often affects their growth.
Mini Oral Quiz-
1.) Compare and contrast epidermis and dermis.
2.) List 5 functions of the skin.
3.) How does skin prevent disease in the body?
4.) Why is a person ho has been severely burned in danger
of dying from loss of water?
5.) How are hair and nails different? How are they the
same?
By :
Emma Cooper
