There is a concomitant stoppage of respiration after initial 'catch'

in inspiration. the Lriynx is closed and is drawn upwards. All these events result in prevention of aspiration of the vomits into the respiratory tract. The palate There is a concomitant stoppage of respiration after initial 'catch' rises and the communication between the nasopharynx and pharynx is cut off This prevents spilling off of the vomitus into the nasopharyngeal and nasal cavity. Ant peristalsis waves may develop in the stomach or duodenum and if This develops it aids in vomiting. However, development of ant peristalsis waves is probably not essential. Vomiting center. This is situated in The medulla, close to the salivary centers. salivations therefore, is common when The vomiting center is stimulated. The vomiting center may be stimulated by a very Large variety of stimuli. Thus inflammation of malady of most of the viscera within our abdomen (gastritis. enteritis, cholecystitis etc.) heart (myocardial infarction) or ghastly disagreeable sight, smell, taste etc. can cause vomiting. Head injury and intracranial Tumor irritate The vomiting center directly by means of raised intracranial tension and cause vomiting. This type of vomiting is called "central vomiting’ Near The vomiting center at medulla There is a "central chemoreceptor trigger zone" (CTZ) which when stimulated, causes a stimulation of the vomiting center in turn. Drugs of the group of phenothiazines (e.g. chlorpromazine or largacticl'. act on this CTZ and thus inhibits vomiting. Nausea and vomiting, particularly in the morning are normally seen in early months of pregnancy and are called "morning sickness"