What Is Skin?
Which layer of skin protects the body from the elements, such as wind and ultraviolet (UV) radiation. It also serves as a barrier to keep bacteria and viruses out and water in. One other important function of this layer is to produce vitamin D
Epidermis
Where are the youngest keratinocytes in the skin found?
New keratinocytes form at the bottom of the epidermis from dividing stem cells.
Melanin is a ___________.
Pigment
What main structure does melanin protect?
DNA
True or False? Most UV radiation that reaches our skin is UVA.
True
Which layer of skin contains blood vessels, lymph vessels, hair follicles, sweat glands, oil glands, and nerve endings. Its function is to supply the epidermis with oxygen and nutrients from blood and to regulate body temperature.
Dermis
Where does the name “keratinocyte” come from?
Their name comes from the fact that they contain the structural protein keratin, which is also found in hair and nails.
The specialized cells that produce melanin are called ___________.
Melanocytes.
Can skin cancers due to UV rays be inherited?
In most cases no
Where in the world is the UV index the highest?
The equator
What layer of the skin contains fat cells, functions mainly to insulate the body, provide a protective padding around internal organs, and store energy.
Hypodermis
What is the function of melanocytes?
They produce the pigment melanin, which gives skin its color.
What are the two types of melanin?
Pheomelanin and Eumelanin
What are some of the biological effects of UVB radiation?
Vitamin D synthesis, DNA mutations in the skin, decreased folate levels
UV radiation has __________________________ wavelengths and _______________________ energy than visible light and infrared radiation.
Increased; Decreased
Why is Vitamin D important for our health?
Vitamin D allows our bodies to absorb Calcium.
How does a melanocyte’s shape relate to its function?
The long projections in melanocytes serve to deliver melanosomes—which are pigment-containing organelles—to keratinocytes.
Dark skin contains more of which type of melanin than fair skin?
Eumelanin
True or False? Once they are delivered to keratinocytes, all the melanosomes end up in the supranuclear cap.
False
True or False? Tanning is a response to DNA damage.
True. If DNA in keratinocytes is damaged by UV radiation, the DNA damage itself and/or the repair mechanism stimulates more melanin production.
What is the connection between the skin, sunlight and Vitamin D?
Ultraviolet B radiation from the sun starts the process that converts the inactive form of vitamin D in skin to the active form circulating in blood.
The top layer of the epidermis is made of dead keratinocytes. What is the function of this layer?
The skin owes most of its tough, waterproof barrier function to this top layer. These dead cells slough off easily and are replaced every 4 to 6 weeks by new keratinocytes that have migrated from the bottom of the epidermis to the top.
Does the amount of melanocytes affect the shade of someone's skin?
Although almost everyone has approximately the same number of melanocytes, the amount and size of the melanosomes and the amount of melanin within them can differ greatly. In general, more eumelanin-producing melanosomes will result in darker shades.
How do UV rays create cancer?
Form genetic mutations in the DNA
Who's your favorite teacher??
Is that even a question?!?