Causes of nausea and vomiting:

 

 

Gastrointestinal related

 

Intestinal obstruction due to tumour in the lumen or gastric stasis (otherwise also known as gastroparesis) a condition where there is paralysis/ weakness of the muscles in the stomach.

This causes food contents in the intestine to remain for prolonged periods with slow movement through the bowel. This slow transit result in the  stretching of the intestine, activating the mechanoreceptors in the gastrointestinal tract. Subsequently, this information regarding distension is relayed to the VC via the vagal afferent nerve. 

 

Anxiety and fear 

Higher centres such as the cerebral cortex are activated when experiencing anxiety or fear. This is a complex mechanism and the pathway is not completely understood. However, it is believed that anxiety induced emesis may be a learned response and no particular neurotransmitters are associated in the cause.

An example of the learned response is demonstrated in anticipatory nausea prior to chemotherapy. This is where patients report feeling nauseous and/or vomits prior to treatment. Certain smell or environment associated with unpleasant chemotherapy will trigger emesis.