Vomiting is controlled by an area of the brain called the vomiting centre. The vomiting centre is responsible
for causing feelings of sickness (
nausea) and
for the vomiting reflex. It is activated when it receives nerve messages from another area of the brain called the chemoreceptor trigger zone (CTZ) and when it receives nerve messages from the gut.
Chemotherapy, radiotherapy and surgery can cause a substance called serotonin (5HT) to be released in the gut.