Ashlynne, Riley, Abby, Sarah, Samantha Skin Ashlynne, Riley, Abby, Sarah, Samantha

Basic Functions -The skin is the largest organ in the human body -the skin is an organ of protection -the skin is a barrier. It provides protection from mechanical impacts, pressure, temperature variation, microorganisms, radiation, and chemicals. -this skin is an organ of regulation -this skin regulates body temperature, sweat, circulation, and fluid balance -the skin has an endocrine function. -the skin is the main source of vitamin D for the body. Through the production of cholecalciferol in the two upper layers of the epidermis .

Basic Functions Cont. -the skin is also for sensation -the skin has a network of nerve cells that detect changes in the environment. -there are receptors for hot, cold, pain, and touch. -if there is damage to the nerve cells, it results in a loss of sensation in that area. -the damage is called neuropathy. This is a dangerous condition because if it gets to severe, those with neuropathy can injure their skin badly and not known because they are unable to feel the pain.

Epidermis The outermost layer of the skin Number one job is protection Outside is made with waterproofing material which lets nothing through Has the ability to replicate cells Made out of epithelial cells 4 main layers: Stratum corneum Stratum basale Stratum spinosum Stratum granulosum

Epidermis and Dermis

Dermis -The dermis is the inner layer of the skin, just below the epidermis -The dermis is a layer of fibrous and elastic tissue that allows the skin to maintain its flexibility and strength. -The dermis has two main layers, a thick lower layer called the reticular dermis, and a thin upper layer called the papillary dermis -The dermis contains: connective tissue, blood vessels, oil, sweat glands, nerves, and hair follicles

Melanin- Skin Color Melanin is a dark brown to black pigment occurring in the hair, skin, and iris of the eye Found in people and animals Dark-skinned people have more melanin than light skinned people Produced by cells called melanocytes Melanocytes produce more melanin to protect your skin from the UV rays Freckles are small, concentrated areas of overproduction of melanin The first step of creating melanin is; catalysts of chemical L-3, 4- dihydroxyphenylalanine by tyrosinase Lack of tyrosinase can lead to albinism

Melanin-Hair Color Two types of melanin; Eumelanin, which is responsible for dark brown or black hair Pheomelanin which causes red and blonde hair Red hair has the highest amount of pheomelanin at around 67% and very little eumelanin. The more melanin one has means, the darker the hair. As you get older, you produce less melanin and melanocytes die off, causing the hair to turn gray or white. The mixture of eumelanin and pheomelanin is determined by your genes MC1R (melanocortin 1 receptor) gene is important in determining hair color. When active in melanocytes, it causes production of eumelanin. When not active, mostly pheomelanin is made, causing red hair. https://www.youtube.com/watch?v=mDiBa0vLmfI

Works Cited (MLA) BrainStuffShow. "What Determines Your Hair Color?" YouTube. YouTube, 10 Mar. 2015. Web. 28 Feb. 2017. <https://www.youtube.com/watch?v=mDiBa0vLmfI>. "Dermis." PubMedHealth, www.ncbi.nlm.nih.gov/pubmedhealth/PMHT0022668/. "Yo-Yo Dieting." MedicineNet - Health and Medical Information Produced by Doctors. N.p., n.d. Web. 23 Feb. 2017.