Absorption through the skin: Oxygen, nitrogen and carbon dioxide can diffuse into the epidermis in small amounts; some animals use their skin as their sole respiration organ (in humans, the cells comprising the outermost 0.25–0.40mm of the skin are "almost exclusively supplied by external oxygen", although the "contribution to total respiration is negligible") [28] Some medications are absorbed through the skin. As skin ages, it becomes thinner and more easily damaged. Intensifying this effect is the decreasing ability of skin to heal itself as a person ages.

The human skin is a rich environment for microbes. [37] [38] Around 1000 species of bacteria from 19 bacterial phyla have been found. [38] [37] Most come from only four phyla: Actinomycetota (51.8%), Bacillota (24.4%), Pseudomonadota (16.5%), and Bacteroidota (6.3%). Propionibacteria and Staphylococci species were the main species in sebaceous areas. There are three main ecological areas: moist, dry and sebaceous. In moist places on the body Corynebacteria together with Staphylococci dominate. In dry areas, there is a mixture of species but dominated by Betaproteobacteria and Flavobacteriales. Ecologically, sebaceous areas had greater species richness than moist and dry ones. The areas with least similarity between people in species were the spaces between fingers, the spaces between toes, axillae, and umbilical cord stump. Most similarly were beside the nostril, nares (inside The body can also encourage heat loss by flushing – allowing hot blood from deep inside the body to flow close to the skin, where its heat will radiate out into the environment. Hatton IA, Galbraith ED, Merleau NS, Miettinen TP, Smith BM, Shander JA (September 2023). "The human cell count and size distribution". Proceedings of the National Academy of Sciences of the United States of America. 120 (39): e2303077120. Bibcode: 2023PNAS..12003077H. doi: 10.1073/pnas.2303077120. PMC 10523466. PMID 37722043. The papillary region is composed of loose areolar connective tissue. It is named for its finger-like projections called papillae, which extend toward the epidermis. The papillae provide the dermis with a "bumpy" surface that interdigitates with the epidermis, strengthening the connection between the two layers of skin. Mammals have hair – strands of protein that grow out of the skin, and which keeps the animal warm by trapping warm air close to the skin. Even humans have tiny, vestigial hairs all over our bodies.The epidermis is the thinnest layer in your skin, but it's responsible for protecting you from the harsh environment. The epidermis has five layers of its own. It also hosts different types of cells: keratinocytes produce the protein known as keratin, the main component of the epidermis. Melanocytes produce your skin pigment known as melanin. Langerhans cells prevent foreign substances from getting into your skin. Dermis: The Middle Layer of Skin Mucous glands are non-venomous and offer a different functionality for amphibians than granular. Mucous glands cover the entire surface area of the amphibian body and specialize in keeping the body lubricated. There are many other functions of the mucous glands such as controlling the pH, thermoregulation, adhesive properties to the environment, anti-predator behaviors (slimy to the grasp), chemical communication, even anti-bacterial/viral properties for protection against pathogens. [23] Storage and synthesis: acts as a storage centre for lipids and water, as well as a means of synthesis of vitamin D by action of UV on certain parts of the skin.

Several scientific studies confirmed that changes in baseline nutritional status affects skin condition. Excretion: sweat contains urea, however its concentration is 1/130th that of urine, hence excretion by sweating is at most a secondary function to temperature regulation. Abdo J, Sopko N, Milner S. The applied anatomy of human skin: A model for regeneration. Wound Medicine. 2020;28:100179. doi:10.1016/j.wndm.2020.100179 The skin may be itchy, scaly, or raw. Lighter skin can appear red, while darker skin may appear purple, gray, or dark brown.

Vitiligo is characterized by loss of pigment in the skin due to autoimmune destruction of the cells that give skin its color. Thorough cleansing. You should perform this twice daily. At night, make sure you remove all your make-up and cleanse properly before going to bed.