Emetics
Emetics are agents that induce and produce the vomiting by stimulation of vomiting center present in medulla oblongata. Those agents are mainly used in poison case and taken orally over dose.
Pathogenesis of Vomiting Occurring / How to produce emesis or Vomiting
Multiple pathways are involved in induce vomiting.
Vomiting center is present in medulla oblongata that
received the impulse and induces vomiting.
Chemoreceptor trigger zone (CTZ) and Nucleus tractus
solitarius (NTS) are send the impulse to Vomiting Center for cause vomiting.
Vomiting center is received impulse in various way,
these are follows:
1) Chemoreceptor trigger zone:
CTZ is located in the area postrema near to vomiting center in medulla
oblongata. CTZ is outside of blood brain barrier. Many poisons and drugs are
present in blood, which can entered CTZ and stimulated it (CTZ). That can
generate the impulse and send to the vomiting center and vomiting induces.
Chemo word comes from chemotherapy, which mainly induces vomiting due to chemotherapy. CTZ express various receptors eg. Dopamine D2
receptor, Histamine H1 receptor, serotonin 5-HT3 receptor, opioid ยต
receptor and cholinergic M receptor.
2) Nucleus Tractus Solitarius (NTS):
NTS received the impulse from gastrointestinal tract (GIT), throat and other
viscera. NTS send to impulse vomiting center and induce vomiting. NTS is
located near vomiting center in medulla oblongata. NTS express a variety of
receptor such as: serotonin 5-HT3 receptor, dopamine D2 receptor,
cholinergic M receptor and histamine H1 receptor.
3) Vestibular Apparatus:
Vestibular apparatus generate impulse when equilibrium imbalance or body rotate
or balance disturb. Than these impulse which generated in the vestibular
apparatus send to the vomiting center and vomiting induce. Cause vomiting due
to motion sickness.
4) Cerebral Cortex:
Cerebral cortex can induce vomiting due to pain, bad smell/odor, sight,
psychogenic stimuli. Cerebral cortex is higher center to direct simulate the
vomiting center and cause vomiting.