GI: Nausea and Emesis Flashcards
What is emesis?
Forceful propulsion of gastric contents from the mouth
What happens to the sphincters in the stomach and oesophagus during emesis?
They are relaxed
What co ordinated vomiting?
The vomiting centre in the medulla of the brain stem and it involves both smooth and skeletal muscle
What is the initial event in vomiting?
Suspension of normal peristalsis in the small intestine followed by retrograde contractions
What happens after vomiting?
Profuse salivation, sweating, tachycardia, nausea
Decribe the events of vomitng?
Deep inhalation
Closure of glottis and raised soft palate
Suspension of breathing
Contraction of diaphragm and abdominal muscles
Ejection of gastic contents
What is nausea?
Subjective unpleasant sensation felt in the the throat and stomach- often relieved by vomiting
What other things can happen when you feel nauseous?
Pallor, sweating
Stomach and LOS relax= tension in gastric and oesophageal muscles
What are the events of nausea?
Contraction of upper intestine followed by contraction of the pyloric sphincter/region
Movement of contents of upper jejunun, duodenun and pyloric region into the the body and fundus
Relaxed lower eospphageal spnincter and oesophagus set the stage for retching and vomiting
What are the consequences of severe vomiting?
Dehydration Loss of gastric protons and chloride- metabolic alkalosis Hypokalaemia Rarely loss of bicarbonate= alkalosis Mallory Weiss tear
What can trigger vomiting?
Pain, repulsive sights, smells, emotional factors Motion sickenss, vestibular disorder Drugsm radiation Stimuli in Gi tract Pregnancy Intracranial pathology
What is the chemoreceptor trigger zone?
Located in the area postrema and is outside the blood brain barrier- detects circulating emetic agents eg opiates
What is the nucleus tractus solitarius?
Senses pharnygeal stimulation, gastric distention or irritation etc- relays this to the VC
What drugs can cause vomiting?
Chemo/radiotherapy Anaesthetic- PONV Dopamin agonists eg Parkinsons Opiates Cardiac glycosides Drugs enhancing 5- HT function
