| CosmeticIndustry_com Information about cosmetics, makeup and beauty. Includes new products, promotions, the competition and what consumers are saying. |
| A_Makeup_Artist_Locator_Service A search service to locate a makeup artist for any occasion. |
| Mascara Features tips, product highlights, skin care/make-up guides, latest trends in make-up/hair and solutions to countless beauty woes. |
| AHRQ__Clinical_Information Clinical information on evidence-based practice, clinical guidelines, medical effectiveness, pharmaceutical therapy, new technology, screening and preventive services, outcomes research, and the Natio |
| AllExperts_Medical_Research_Q&A Experts volunteer to answer questions related to locating medical resources on the internet. |
| Australian_Association_of_Academic_General_Practice A non-profit association to further research and teaching by general practice physicians in Australia. |
| Bio-Forum_net Research discussion group. |
| Center_for_Evidence-Based_Medicine Includes introductory tutorials on practising and teaching evidence-based medicine. |
| CoGENT Collaboration of clinical research studies on depression, obsessive-compulsive disorder (OCD), schizophrenia, survivors of childhood ual abuse, and neurogenetic & neurodevelopmental disorders a |
| Controlled_Trials_from_History A historical examination of research methods designed to reduce biases in studies assessing the effects of health care, social care and education. Contains many images of historical items. |
| Entrez-PubMed National Library of Medicine's search service provides access to over 10 million citations in Medline, PreMedline, and other related databases, with links to participating online journals. |
| Evidence-based_Decision_Making The primary purpose of this site is to support health care decision making. Includes summarized key articles, through the use of a critical appraisal journal club, application of EBDM principles and l |
| The_INCLEN_Trust International Clinical Epidemiology Network for research and training to improve efficiency and quality of healthcare for disadvantaged populations, particularly in low- and middle-income countries. |
| Inside_Medicine Offers descriptions of current research on a wide variety of diseases and medical conditions. |
| Life_and_Molecular_Medicine Interesting, eclectic collection of information and links regarding the latest developments in this new field and how these advances relate to your life. |
| Medical_Hypotheses A forum for the presentation and criticism of ideas in medicine and the related biomedical sciences. |
| National_Institutes_of_Health_(NIH) US Government department in charge of medical research. |
| SoCRA Educational and charitable nonprofit membership organization, offering educational programming and certification to clinical (health care) research professionals and others interested in clinical(heal |
| Survey_Research_Group Offers medical research questionnaires, women's health research, industry analysis, and health statistics in the medical research field. |
| The_UK_Health_Technology_Assessment_Programme Site contains details of program's many projects and publications; an NHS national research and development initiative. |
| U_S__Preventive_Services_Task_Force_(USPSTF) Panel of health care experts that evaluates the latest scientific evidence on clinical preventive services. |
| WebExhibits_Directory-Medicine Interesting topics in biomedicine. |
| About_com__Healthy_Herbs Weekly features and extras, product and book reviews, free newsletter, chat and bulletin board from About.com. |
| Alternative_Nature_Herbals Includes articles, herb profiles with horticulture and remedy information, a gallery of photographs, and links to other herbal sites. |
| American_Botanical_Council Provides information about the responsible use of herbs and phytomedicines. Includes news, information on their events, and a guide to common herbs. |
| BC_Herb_Growers_Association Provides information about the organization and its members, news, educational opportunities, and an online herb database. |
| Botanical_Dermatology_Database An electronic, searchable version of "Botanical Dermatology," by John Mitchell and Arthur Rook, which includes a botanical index. |
| Bouquet_Garni_Herbs Provides information about growing herbs, and using them for health, beauty, and cooking. |
| Culpeper\'s_Herbal_Online Full text of Culpeper's Complete Herbal (1653 edition). Includes breakdown by individual herb, directions for making remedies and catalog of simples. |
| The_Daisy_Institute Information and testimonials about using herbal remedies for various life-threatening diseases. |
| Diet-and-Health_net__Naturopathy Includes list of herbs using in naturopathic remedies, with information about their uses and hazards. |
| Directory_of_Herbs A list of herbs and plants and their magical properties. |
| Elchai\'s_Herbal_Lore_and_Remedies Information preparations and formulas, therapeutic terms, and ceremonial use. Also includes herb profiles with uses, actions, precautions, and active constituents. |
| Essiac_Information_Site Information about the herbal tea known as essiac, including history, controversial issues, scams, marketer ethics, product prices, and recipes. |
| Evening-Primrose-Oil_com Provides articles and information about the possible health uses of evening primrose oil, including PMS, autoimmune conditions, inflammation, and weight loss. |
| goodHealthinfo_net Seven Boston-area herbalists discuss their approaches to correcting imbalances in the body's energy, using herbs and muscle testing. |
| GreyWing’s_Herbal An online text with chapters about history, harvesting, drying, horticulture, preparations, and therapeutic actions. |
| Healing_Herbs An interactive community offering herbal information, recipes, chat, discussion groups, events, gardening information, and herb photos. |
| The_Herb_Coach An e-zine containing herbal and natural health news. |
| The_Herb_Index An online guide for herbs and supplements, includes scientific names and contra-indications. |
Random Article 
Search HowStuffWorks and the web 
Home AdventureAnimalsAutoCommunicationComputerElectronicsEntertainmentFoodGeographyHealthHistoryHome & GardenMoneyPeopleScience AnatomyBiotechnologyHealth & IllnessHuman NatureLife StagesDeath & DyingMedical Encyclopedia & Reproduction Home > Health > Health & Illness > Wellness > Beauty & Hygiene Next Page 
Please copy/paste the following text to properly cite this HowStuffWorks article:Brain, Marshall. "How Sunburn and Sun Tans Work." 01 April 2000. HowStuffWorks.com. <http://health.howstuffworks.com/sunscreen.htm> 02 December 2008. Inside this Article Introduction to How Sunburn and Sun Tans Work The Dermis Tanning Sunburn Sunscreens Lots More Information See more » See all Beauty & Hygiene articles How Sunburns Work 
More Health Videos » 
There is something mysterious about the sun and skin. Why is it that if you go out on a bright summer day and spend an hour in the sun, you get a sunburn? You get a sunburn, that is, unless you happen to have taken the time to get a gradual tan. With a tan you can go out in the sun and nothing happens. Of course, that doesn't apply if you have "fair skin." The fair skinned among us never get a tan, so they always get sunburned. Unless of course they are wearing a sunscreen...Does this make sense? What exactly is a sunscreen? And what is a tan? What is the difference between a tan and a burn? Why can you spread a little blob of lotion on yourself and be protected, but if you forget you are miserable?If you take the time to look at skin and sunlight in some detail, all of this actually does begin to make sense. You can learn a huge amount about your body in the process. So, that's what we'll do in this article. First, let's take a look at how skin works. How Skin WorksSkin is one of the most amazing organs in the human body. It is hard for us tothink about it as an organ, however. We tend to think of organs as boxy things. Yourheart, liver, kidneys - those are obviously organs. But skin is an organtoo, especially if you look at the dictionary definition of "organ", like thisdefinition from the Merriam Webster Collegiate Dictionary:Organ - a) differentiated structure (as a heart, kidney, leaf, or stem) consisting of cells and tissuesand performing some specific function in an organism b) bodily parts performing a function or cooperating in an activity By that definition, skin is definitely an organ. Skin is made up of very specific cells and tissues, andtheir collective purpose is to act as the boundary between "you" and "the world". One of the neatthings about skin that makes it different from a lot of other organs is the fact that it does haveto deal with the real world. Therefore it is loaded with sensors, and it also has a very toughlayered design so that it can handle realities of the environment like abrasion and sunlight.If you take a look at a cross section of typical skin (like the skin on your arm or leg) you find thatit is made up of two main layers: the epidermis on the outside and the dermis on the inside. Theepidermis is the barrier, while the dermis is the layer containing all the "equipment" -- things like nerveendings, sweat glands, hair follicles and so on. Here's a picture to help you see what is going on:
In the subcutaneous layer (you may have heard of subcutaneous fat --this is where it lives) you can see the blood vessels (shown as two thin red and blue lines).These vessels branch infinitely (not shown) into thedermis to supply the sweat glands, hair follicles, sebaceous glands and erector muscles with blood. Theyalso fan out into the dermis's capillary bed.It turns out that the dermis is loaded with capillaries. Capillaries satisfythe nutritionalneeds of the cells in the dermis, and they also help the skin perform an important cooling function in humans.The epidermis has no direct blood supply, but instead is supported and fedby the dermis. Next Page Inside this Article Introduction to How Sunburn and Sun Tans Work The Dermis Tanning Sunburn Sunscreens Lots More Information See all Beauty & Hygiene articles digg_url = 'http://health.howstuffworks.com/sunscreen.htm'; digg more 
buzz more stumble_url = "http://health.howstuffworks.com/sunscreen.htm" Related Ad Categories /* '); document.write(''); for (i = 0; i < 3; ++i) { document.write('' + radlinks[i].term + ''); } document.write(''); document.write(''); for (i = 3; i < radlinks.length; ++i) { document.write('' + radlinks[i].term + ''); } document.write(''); document.write('');}var ads = new Array;google_ad_output = 'js';google_ad_client = 'ca-howstuffworks_radlinks_js';google_ad_channel = 'health-Article';google_safe = 'high';google_num_radlinks = 5; // Number of radlink terms to returngoogle_max_radlink_len = 23;google_max_num_ads = '0';google_prev_ad_formats = '';/* ]]> */ 
Related ContentExplanationsHow do sunless-tanning products work?How to Prevent WrinklesWhat is "sunburn"? Prices: Sunscreen 
Kiss My Face Sun Screen with Oat Protein Complex 18 SPF - 4 oz. Kiss My Face combines Oat Protein and Oat Beta Glucan a dynamic duo of patented ingredients reduce irritation and inflammation and also fight against ...$7.13 
Soltan & Piz Buin Spf 30 & 15 Tanning Sun Screen eBay offers you smart deals and the widest selection, ranging from the everyday basics to things that are as unique as yourself. With millions of item...$13.99 
Mechanic´s Sun Screen Protect your skin from burns and premature aging while you work outdoors! Mechanic's Sunscreen blocks over 90% of harmful UV rays with a refreshing, a...$3.99 
© 1998-2008 HowStuffWorks, Inc. Discovery Communications, LLC | Discovery Channel | TLC | Animal Planet | Discovery Health | Science Channel | Planet Green | Discovery Kids Petfinder | TreeHugger | Military Channel | Investigation Discovery | HD Theater | FitTV | Turbo ATTENTION! We recently updated our privacy policy. The changes are effective as of Thursday, October 30, 2008. To see the new policy, click [here]. Questions? See the policy for the contact information. if (adBackgroundColor == '') { $("body").css("background-image","url(http://static.howstuffworks.com/en-us/default/layout/bg_page.gif)"); } else { realMediaPM.setColor(adBackgroundColor); }var s_account="disccglobal";