Treatment of Vomiting and Gut Motility Disorders

Question 1

Central neural regulation of vomiting is controlled by 2 separate units both in the medulla:

Answer 1

1) The Vomiting (emetic) centre

2) The Chemoreceptor Trigger Zone, CTZ

Question 2

Vomiting centre

Answer 2

multiple sensory, motor and control nuclei

- mainly in the medullary and pontine reticular formation which also extends into the spinal cord

Question 3

where does the vomiting centre receive nerve impulses from

Answer 3

both vagal and sympathetic afferent nerve fibres and responds to oncoming signals to coordinate emesis

Question 4

where - Chemoreceptor Trigger Zone

Answer 4

the area postrema in the floor of the 4th ventricle

Question 5

what is the role of the chemoreceptor trigger zone

Answer 5

this is sensitive to chemical change and is the main site of action of drugs which stimulate vomiting

also mediates motion sickness

Question 6

what causes motion sickness

Answer 6

certain kinds of movement and the origin of the stimuli is primarily the vestibular apparatus

Question 7

What is the journey from experiencing motion sickness, to actually being sick

Answer 7

vestibular labyrinth > vestibular nuclei (brain stem) > cerebellum > CTZ > vomiting centre > vomit

Question 8

what are the three stages of vomiting

Answer 8

nausea
retching
vomiting

Question 9

what are the three types of vomiting

Answer 9

• projectile vomiting
• haematemesis
• early-morning

Question 10

what is the role of antiemetic drugs

Answer 10

to stop nausea/vomiting

dont prescribe unless the cause of the vomiting is known

Question 11

what are potential indications for antiemetic drugs

Answer 11

1. Severe vomiting during pregnancy / hyperemesis gravidarum
2. Postoperative nausea and vomiting
3. Motion sickness
4. Other vestibular disorders
5. N/V induced by cytotoxic chemotherapy
6. Palliative care
7. N/V associated with migraine