prescriptions: a prescription is an official document from a doctor stating which medicine you should have
saying: a saying is a well-known phrase or expression which states something wise or true about life
a good guffaw: a strong and noisy laugh
trigger: to cause something to happen quickly – here, the release of particular chemicals in the body
feel-good effect: ability to make you feel happy and positive about life

Use one of the words or phrases below to complete each of these sentences from a BBC news report.
Note that you may have to change the form of a word to complete the sentence correctly.
prescription / saying / a good guffaw / trigger / feel-good effect
1.
The type of laughter was also important. Tittering and giggling did not elicit any physiological effect; only ________________ did the job.
2.
In 2002, specially trained nurses were given the right to write ________________ for a wide range of drugs, including antibiotics for infections.
3.
Breathing in heavy traffic fumes can ________________ a heart attack, say UK experts.
4.
Dr James Byron-Daniel said: "There is evidence that exercise stimulates the same part of the brain as drinking and smoking, mimicking the ________________- the same kind of effect that is seen when people eat chocolate and sugary snacks.
5.
She lives in the US and is spending her summer holidays with me here in Ghana and as the ________________ goes, out of the mouths of babes, I have been learning a few home truths.