The dermis is composed of three major types of cells:[3] fibroblasts, macrophages, and mast cells. 5. Few microfilariae were recovered from blood but large numbers were in the reticular layer of the dermis, especially in skin of the ears. The papillary region is composed of loose areolar connective tissue. For this reason, if you cut the epidermis there is no bleeding, but if the cut penetrates to the dermis there is bleeding. The dermis is one of the three constitutive layers of the skin, situated between the epidermis and the hypodermis , and is composed of two layers, the papillary dermis lying immediately below the epidemis and the reticular dermis.It is a 2 to 4 mm-thick layer of connective tissue mainly composed of extracellular matrix (ECM) produced by fibroblasts. Sweat and sebum reach the skin's surface through tiny openings in the skin that act as pores. epidermis sits on top of it. Flashcards. Where exposure to friction is greatest, such as in the fingertips, palms, and soles, the epidermis has five layers—stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, and a thick stratum corneum. Spell. Their long, slender projections extend between the keratinocytes and transfer melanin granules to them. Once inside keratinocytes, the melanin granules cluster to form a protective veil over the nucleus, on the side toward the skin surface. [5], The dermal papillae are part of the uppermost layer of the dermis, the papillary dermis, and the ridges they form greatly increase the surface area between the dermis and epidermis. Its thickness varies depending on the location of the skin. Both are made of connective tissue with fibers of collagen extending from one to the other, making the border between the two somewhat indistinct. The epidermis is a thinner portion of the skin, which is composed of epithelial tissue. With age, the papillae tend to flatten and sometimes increase in number. Furthermore, elastic fibers in the dermis provide the skin with stretch-recoil properties. It nourishes the hypodermis and the structures located within the deeper portions of the dermis. Its extracellular matrix contains thick bundles of interlacing collagen and elastic fibers that run in many different planes. Reticular fibers 4. Large stem cells, termed basal cells, dominate the stratum basale. It intertwines with the rete ridges of the epidermis and is composed of fine and loosely arranged collagen fibers. Several distinct layers of keratinocytes in various stages of development form the epidermis. Skin has two main layers, both of which serve a purpose. The dermis is the inner of the two major layers that make up the skin, the outer layer being the epidermis. Thus, many jabs and scrapes do not penetrate this tough layer. Write. This is called thick skin. It also contains most skin structures such as glands and blood vessels. These projections of the dermal papillae into the epidermis increase the surface area for exchange of gases, nutrients, and waste products between these layers. It is your “hide” and corresponds to animal hides used to make leather products. AND YET EVEN MORE SKIN STUFF. Add to favorites 0 favs. The outermost care of the skin is essential. Flexure lines are also visible on the wrists, soles, fingers, and toes. Most of the skin is 1 to 2 mm thick, but it ranges from less than 0.5 mm on the eyelids to 6 mm between the shoulder blades. Their role in the immune response is to help other cells of the immune system recognize an invading microbe and destroy it. Dermis: The lower or inner layer of the two main layers of cells that make up the skin.The dermis contains blood vessels, lymph vessels, hair follicles, and glands that produce sweat, which helps regulate body temperature, and sebum, an oily substance that helps keep the skin from drying out. Today 's Points. Thus, fingerprints are “sweat films.”. The dermis is also the site where all the accessory structures of the skin – your hair, nails, and a variety of multicellular exocrine glands originate. 0. On the palms of the hands and the soles of the feet, the dermal papillae lie atop larger mounds called dermal ridges. View as Printable Worksheet. On the eyelids, it's 0.6 millimeters thick. Observe, for example, the deep skin creases on your palm. Helps you adjust to outside temperatures dermis, which create fingerprints, palm-prints, and are easily by... Easily damaged by UV light across cleavage lines is important to surgeons animal hides used to leather. 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