Skin Care Flashcards
What is the the type of light in sunlight?
Ultraviolet (UV) light.
What is UV?
High-energy radiation which causes many chemical reactions in our skin.
What chemical reactions in our skin are caused by UV?
Production of vitamin D, tanning, burning, and ageing.
What is used to prevent sunburn?
Sunblocks
What is in sunblocks?
Compounds like titanium dioxide reflect the UV light and stop it from reaching the skin.
How do sunscreens work?
They contain chemicals that act as UV filters and reduce the amount of UV reaching the skin.
Why can excessive exposure to the sun make you appear older?
The sun’s rays change the skin’s texture by weakening its elasticity, causing the skin to sag and appear leathery.
What can exposure to UV light result in?
Molecules gaining enough energy for chemical bonds to be broken. This is what causes sunburn and contributes to the ageing of skin.
How are free radicals formed?
When UV light breaks a molecule’s bonds.
What are free radicals?
Molecules that have unpaired electrons meaning they are very reactive and will react quickly with neighbouring atoms to form bonds.
What are photochemical reactions?
Reactions that are initiated by light.
What are the three stages of a free radical chain reaction, in order?
Initiation, Propagation, Termination.
What is the initiation stage of a free radical chain reaction?
When free radicals are formed due to a molecule absorbing radiation.
What is the propagation stage of a free radical chain reaction?
The free radicals react forming further free radicals which also go on to react.
What is the termination stage of a free radical chain reaction?
Free radicals combine slowing the rate and stopping the reaction.
How are free radicals written?
They have no charge so instead have a dot next to the letter.
How many steps does the propagation part have in a free radical chain reaction?
At least two.
What are free radical scavengers?
Our body produces chemicals that will react with free radicals.
What’s a common example of free radical scavengers?
Antioxidants
How do free radical scavengers work?
They react with and therefore removing the free radicals, stopping the chain reactions.
What happens to free radicals as we age?
The process already doesn’t completely prevent damage, but as we age they become less effective.
What are examples of natural antioxidants?
Vitamins C and E.
What derivative of antioxidants is used in cosmetics?
Polyphenols from vitamin C and E - it is thought to penetrate the epidermis and dermis.
What can cause plastics to degrade?
Free radicals formed in the atmosphere by UV radiation.
What can happen to plastics after UV radiation?
They can discolour and crack.
What is added to plastics to prevent degradation?
Free radical scavengers to act as UV stabilisers.
What is a common free radical added to plastics?
Benzophenone - it reacts with reactive oxygen species, preventing damage.
