Diffusion and osmosis play important roles in transporting substances through the skin. Diffusion allows molecules like medicines, nutrients from food, and essential oils to pass from areas of high concentration to low concentration through the skin and into the bloodstream. Osmosis transports water and keeps tissues hydrated. If these processes failed, important substances like nicotine from patches, hormones from HRT treatments, and moisture wouldn't be able to enter the skin, potentially causing issues like nicotine withdrawal symptoms, low hormone levels, and dehydrated tissues.