Above: Image © SimplyCreativePhotography, iStockphoto.com

This warning is very important if you’re camping or hiking because poison ivy is often found growing on the forest floor. Poison ivy is a low-growing shrub, but it can also grow like a vine. Vines can growlaterally from a single shoot or bud, making it appear that the plant is growing in a straight line.

Did you know? Poison ivy is a woody perennial, it’s scientific name is Toxicodendron radican.

We call this plant "poison ivy" because if it comes in contact with your skin you will develop a very itchy red rash. This rash can start small, but will spread and can even produce blisters — an allergic reaction to a toxic oil found on the plant, called urushoil.

Did you know? The medical name for a poison ivy rash is "urushiol-induced contact dermatitis".

Once urushoil gets on your skin, it binds to receptor proteins located on the surface of specialized skin cells called Langerhan’s cells. These Langerhan’s cells then interact with specialized cells of the immune system, called T-cells. The job of T-cells is to protect your body from suspicious or foreign substances like urushoil, as well as bacteria and viruses. These immune cells respond aggressively by releasing enzymes to destroy the foreign substance and any nearby cells. During this immune response,your skin turns red because extra blood is sent to that part of your skin (a process called vasodilation) and it becomes itchy because the immune cells also destroy nearby nerve endings.

Only humans are sensitive to urushoil. Animals are not harmed by urushoil and they will not develop a rash if they touch poison ivy because they don’t have the same immune response as humans. In fact, many animals, such as deer, goats, horses, and even birds, will eat the leaves of poison ivy. You, on the other hand, definitely don't want to eat poison ivy, since it will result in lots of unpleasant symptoms!

Did you know? The best way to remove urushoil from your skin is with alcohol.

The good news is that a poison ivy rash is easily treatable and only last a few weeks.

Learn More!

http://www.omafra.gov.on.ca/english/crops/facts/99-015.htm#distribution

http://www.poison-ivy.org/html/faq.htm

http://www.medicinenet.com/poison_ivy/article.htm

http://www.webmd.com/allergies/tc/poison-ivy-oak-or-sumac-topic-overview

Article first published March 14, 2011.

Narveen Jandu

Narveen is currently a Lecturer in Cell Biology and a Curriculum Fellow in Cancer Biology at Harvard Medical School. Prior to moving to Boston, she was a post-doctoral research fellow at Stanford University, where she was studying the interactive effects of gut microbes on immune cell homing and trafficking. Narveen received her PhD from the University of Toronto - her thesis was on the pathogenic effects of Escherichia coli O157:H7 on an innate immune signalling cascade of intestinal epithelial cells. Prior to her PhD training, she completed a Master's degree at McMaster University and she completed her undergraduate degree at Wilfrid Laurier University.


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