2.  The integumentary system consists of the human skin.  The skin is the largest organ in the body like the other organs, has the task of keeping the human body healthy.  It itself acts as a shield to keep out dangerous substances or organisms.  These threats include damage from heat, light, and bacterial or viral infection.  Procedures are taken within the skin, depending on the specific area, to keep the organ healthy.  There are three layers: The Epidermis The Dermis The Hypodermis

3.  Or the “outermost skin”, is comprised of three to five strata, or layers, which contain four different types of cells: 1. Keratinocytes create the protein, Keratin, which strengthens the skin and allows it to be waterproof and flexible. 2. Melanocytes produced melanin, which gives the skin its dark pigments 3. Merkel’s Cells are sensory receptors that allow the skin to feel pressure. 4. Langerhan’s Cells aids the immune system by processing antigens.  The outermost layer of the epidermis is the Stratum Corneum, and it is made up of rows of dead cells, which contain soft keratin to keep the skin moist.  Stratum Lucidum, the fourth strata, only appears on frequently used areas of skin such as palms and soles of our feet. It’s purpose is to protect the skin from ultra-violet rays.  Next the Stratum Granulosum, is where the production of keratin is held, and desquamation takes place. Desquamation is when keratinocytes are pushed up, and keratin is produced until they reach the surface, where the dead cells fall away. A new epidermis is formed every 35 to 45 days.

4.  In the fourth layer, Stratum Spinosum, spiny prickle cells link to create the support for the epidermis.  The deepest strata is the Stratum Basale, and it is the thin layer separating the epidermis and the dermis. This layer of cells is constantly dividing, and as it replicates, the old cells are pushed toward the surface. The layers of the epidermis Real picture of desquamation

5.  The second layer of the skin is also known as “the true skin”.  There are three key components which include: 1. Collagen, which is a protein that gives strength to the layer. 2. Reticular Fibers are slim protein strands that support the stratum. 3. Elastic Fibers are proteins that allow the flexibility of the layer.  The dermis has two layers that are very similar and easy to confuse for each one for the other. Papillary Layer  Loose connective tissues  Located right under the epidermis, and it has papillae that connect to the layer above  Papillae sometimes contains capillaries that aids the epidermis. Other times there are Meissner’s corpuscles, sensory receptors.  Double ridges on finger pads are what forms fingerprints. Reticular Layer  Dense connective tissues  Collagen fibers are woven into durable elastic networks that form patterns called Langer’s Lines.  Within the layer there are Pacinian corpuscles as well, that are deep pressure sensory receptors.

6.  The Reticular Layer contains a number of other important factors: Sweat glands regulate the temperature by excreting liquid out and allowing it to evaporate Sebaceous glands are connected to hair follicles and they secrete oils to waterproof the skin to prevent microbe build up. Lymph vessels transport lymph, white liquid containing white blood cells, to fight threats Blood vessels transport oxygen and nutrients, as well as waste to and from the skin. Vitamin D is also moved through these vessels to the rest of the body. The Papillary and Reticular Layers

7.  The deepest layer that consists of fat and loose connective tissue.  This layer has three jobs: Insulation of the body Cushioning to prevent injury to arteries and internal organs Storage of excess energy  Specialized connective tissues called Adipose tissues store excess energy as fat.  The hypodermis also connects the skin to the deep tissues with collagen, elastin, and resticular fibers that extrude from the dermis. On the right: Adipose Tissue On the left: Real Picture of skin layers

8.  There are specific needs that need to be tended to in order to keep the skin at its optimum condition.  One essential condition is nutrition. Eating water rich foods keep a strong blood flow. Strong and steady blood flow nourish skin cells, and keeps the skin healthy.  Another is proper cleaning. Thorough cleaning can reduce any breakouts of acne.  For protection, sunscreen should be put on all days of the year, even in the winter.  A consistent good night’s sleep can keep the skin healthy and supple. Sleep gives lots of oxygen and blood supply, which makes the skin healthy.

9.  Many outside threats can harm the skin, and ultimately cause diseases in the skin.  Some threats include alcohol, cigarettes, stress, UV lights, chemicals, fire retardants, and industrial by-products.  These dangers harm the skin and cause various diseases.  For example, alcohol and cigarettes can increase wrinkles and can also make it seem like your skin is dying.  Some common skin diseases are: › Acne, warts, skin cancers, hives, dermatitis, etc.

10.  Melanoma is a type of skin cancer that is fatal and its incidence is rising faster than any other human cancer.  There are 4 different types of melanoma: › Lentigo Maligna Type › Superficial Spreading Type › Nodular Type › Acral-Lentiginous Type  Lentigo Maligna Type is usually found on the head and neck section. It starts as a patch with irregular borders and color variations. The patch expands over time and penetrates into deeper levels of skin.  Superficial Spreading Type is found on the trunk, upper arms, and thighs. This starts as a macule, or a discolored spot in the skin, much like the patch. This penetrates into deeper levels of skin faster than the Lentigo Maligna Type.  Nodular Type can be found anywhere on the body. This penetrates very quickly and forms a raised nodule, or a small mass of tissue.  Acral-Lentiginous Type is found on the hands, feet, and nail beds. It is similar to the first two types and takes a long time before it penetrates.

11.  Biology Textbook  Internet: http://medicalcenter.osu.edu/patientcare/healthcare_services/skin_c onditions/anatomy_skin/Pages/index.aspx http://medicalcenter.osu.edu/patientcare/healthcare_services/skin_c onditions/anatomy_skin/Pages/index.aspx  http://finity.adam.com/pages/guide/reftext/html/skin_sys_fin.html http://finity.adam.com/pages/guide/reftext/html/skin_sys_fin.html  http://biology.about.com/od/organsystems/ss/integumentary_system _3.htm http://biology.about.com/od/organsystems/ss/integumentary_system _3.htm  http://dermatology.about.com/od/melanoma/a/meltypes.htm http://dermatology.about.com/od/melanoma/a/meltypes.htm  http://dermatology.about.com/od/skindiseases/Skin_Diseases.htm http://dermatology.about.com/od/skindiseases/Skin_Diseases.htm  Video:  http://health.howstuffworks.com/skin-care/daily/tips/5-everyday- skin-needs.htm http://health.howstuffworks.com/skin-care/daily/tips/5-everyday- skin-needs.htm