Nicotine changes levels in the brain directly, altering behavior.

How do the uv rays cause damage?   what exactly causes the skin to burn;   can you be more specific about this mechanism?   3. how do photosensitive medications increase a person's sensitivity to sunlight and therefore increase their risk of getting burned?     what kind of medications can increase photo-sensitivity, can you think of some examples?

Exercise equipment compensates for acting irresponsibly are disregarding the rules of physical activity

Not type of personal health monitor can calculate the number of calories a person burns. true or false?