Describe the process known a keratinization? Do Now 12/7- 12/10 Define cytoplasm Describe the process known a keratinization? Which layer of your skin contains keratinized cells? What is the specific stratum in which we find these cells?

Comic Strip As promised, you have 10 minutes at the start of this class to finish your comic strip. That means it should be PERFECT. Remember to include: Creation by the basement membrane The movement upwards Keratinization Eventual shedding from body Must be in color, must have text boxes explaining the stages you are illustrating

Unit 4: Skin Color Daily Objective: SWBAT explain the physiology of melanocytes and relate it to differing skin colors and Vitamin D

Big Idea: Skin Color In the past, there have been huge debates on what causes the differences in skin color and how different people of different colors really are. Understanding the physiology of skin color and the controlling components of its expression is key to being able to discuss the real answers behind this issue and putting the myths to rest.

Vocabulary You should already have defined the following, or know about it from prior knowledge but let’s review the following in our notes. Melanin Melanocyte Pigment

Melanocyte Cells that sit right above the basement membrane. They produce melanin which is the pigment that gives our skin its color. They have large cellular extensions that extend upwards through the epidermal cells and distribute melanin into those cells (although it is the only cell that is able to produce it). All people have the same number of melanocytes, but they differ on the amount of melanin they produce.

Melanin The pigment that gives our skin its color. No melanin leads to white skin, lots of melanin leads to black skin, and varying amounts lead to the varying degrees of colors we see in between.

So why is melanin important? Protects us from the harmful UV rays of the sun. The more melanin, the more protection we have. Check for understanding: What are UV rays? Radiation Where does it come from? The Sun Black Lights LEDs Is it good? Or bad? Depends… Gives us a tan, provides vitamin D, Causes skin cancer, melanoma

So what determines how much melanin we make? The amount of melanin is related mostly to genetics but also have environmental factors. People whose ancestors lived in areas with lots of direct sunlight tend to have genes that lead to darker skin while people who lived in areas that had less sunlight have genes for lighter skin. The exposure to direct sunlight will also affect the amount of melanin produced. When your body notices you are getting more exposure to sunlight, it will produce more melanin to protect your body (and that is how you get a tan).

Melanin… so good I just can’t get enough! Why not just have really dark skin all the time? Two reasons: It takes energy to make melanin, and the body doesn’t want to use the energy unless it has to We have to let at least a little sunlight through to the dermis so that we can make Vitamin D

What the heck is Vitamin D???? Vitamin D is needed for our bones and teeth to grow and is important in making certain types of antibodies. If we blocked all of the sunlight, then we wouldn’t be able to make any Vitamin D. REMEMBER: Your skin can synthesize this from the UV rays! (Function of Integument) So instead, we make just enough to protect us but also allow enough sunlight in to make all the vitamin D we need.

Albinism Discussion Pre Reading Questions: 1. What do you think an albino is? 2. What races can be afflicted by albinism? 3. Do you know of any other medical issues associated with the skin disorder? http://www.npr.org/blogs/pictureshow/201 2/11/21/165652046/portraits-of-albinism- letting-an-inner-light-shine

Connect the facts… Write a letter to the person they think has the most different skin color from them explaining why they have different skin colors. They must include a mention of what causes our skin to have color, what controls how much color we have, and some reasons why they might have different colors as well as why we don’t all have genes for having dark skin.

Closing Revisiting the Big Idea Every structure in your body MUST have a specific function. Why? If you are going to invest energy and resources into maintaining these features they better be doing something to sustain your life. That’s why we have to know structure, function and location of every feature.