how does the latter effect?
Through their direct effects on mast cells.
Anaphylaxis
Physical factors such as exercise (known as exercise-induced anaphylaxis) or temperature (either hot or cold) may also act as triggers through their direct effects on mast cells. 
true or false anaphylaxis generally only affects the skin and eyes Incorrect. why does this happen? Common causes include insect bites and stings, foods, and medications. Other causes include latex exposure and exercise.
wiki:13495677
Anaphylaxis [SEP] Causes
Anaphylaxis can occur in response to almost any foreign substance. Common triggers include venom from insect bites or stings, foods, and medication. Foods are the most common trigger in children and young adults while medications and insect bites and stings are more common in older adults. Less common causes include: physical factors, biological agents such as semen, latex, hormonal changes, food additives such as monosodium glutamate and food colors, and topical medications. Physical factors such as exercise (known as exercise-induced anaphylaxis) or temperature (either hot or cold) may also act as triggers through their direct effects on mast cells. Events caused by exercise are frequently associated with cofactors such as the ingestion of certain foods or taking an NSAID.