February 13, 2012 Dermis Below your epidermis lies a thicker layer called your dermis. In contrast to your epidermis, which is constantly replacing itself, your dermis remains pretty much the same throughout your life. Your dermis houses a number of structures, the most prominent ones being: Blood vessels, which allow delivery of nutrients to your skin cells, removal of waste products, and transportation of specialized cells of your immune system whenever they are needed to combat an infection. Lymphatic vessels, which provide a transportation network for immune-related cells, and also balance the distribution of fluids throughout your body. Nerve endings, which allow you to sense pain, temperature changes, and different pressures and textures through your skin. Hair follicles, which are the roots of the hairs that exist throughout your scalp and skin, except on the palms of your hands and the soles of your feet. Sebaceous glands, which produce and secrete sebum, an oily substance that helps to protect you against infection and helps to make your skin water resistant. Sweat glands, which produce and secrete sweat. Collagen, which is a protein that gives your skin strength and flexibility. Elastin, which is a protein that gives your skin the ability to return to its original shape whenever it is manipulated. How Your Skin Keeps You Healthy Being the largest organ in your body, your skin plays a number of critical roles in keeping you healthy, the most important ones being: Physical barrier for protection – the most important function of your skin is to prevent harmful microorganisms from entering your blood. Your skin accomplishes this through three main features: The way in which its cells are tightly organized. Regular production of sebum. The presence of large colonies of friendly bacteria that produce a number of substances that destroy unfriendly organisms – this is why using anti-bacterial soap is a bad idea. Regulator of body fluids and temperature – your skin helps to regulate body fluid balance, pH balance, and your core temperature by manipulating its blood supply and sweat production. Channel for elimination of waste products – through your sweat glands, your skin eliminates waste materials like urea, toxic metals, and excess lactic acid that is created by overworked muscles. Physical protection and detection of dangerous stimuli – your skin provides a layer of cushion for the rest of your body, protecting it against injury. Your skin also allows you to sense danger (hot temperatures, sharp objects, too much pressure, etc.) through sensory receptors that are located throughout your body – mainly in your hands, feet, and lips. Dr. Lawrence Jaeger is a board certified dermatologist who has a practice in New York. Dr Lawrence Jaeger specializes in the treatment of all skin, hair and nail disorders including all skin growths.