Physiology of Nausea and Vomiting Flashcards Preview

Gastrointestinal > Physiology of Nausea and Vomiting > Flashcards

Flashcards in Physiology of Nausea and Vomiting Deck (18)
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1
Q

what is nausea

A

subjective, highly unpleasant ‘sinking’ sensation

felt in throat and stomach

2
Q

describe retching

A

dry - no efflux of vomitus

3
Q

describe vomiting

A

forceful expulsion of gastric/intestinal contents out of the mouth

4
Q

events in vomiting

A

Commences with forceful inspiration, reflex closure of the glottis and elevation of the soft palate to close off the airways and nasal passages
stomach, oesophagus and associated sphincters are relaxed

5
Q

major consequences of severe vomiting

A
dehydration 
loss of gastric protons and chloride 
hypokalaemia 
loss of duodenal bicarbonate (rare)
oesophageal damage (rare)
6
Q

chemoreceptor trigger zone (CTZ)

A

vagal afferents to VC stimulated by;
mechanical stimuli
pathology
toxic materials and drugs in the blood

7
Q

nucleus tractus solitarius (NTS)

A

vagal afferents to VC stimulated by;
mechanical stimuli
pathology

8
Q

what is the vomiting centre (VC)

A

group of interconnected neurones to co-ordinate vomiting

9
Q

where is motor output that co-ordinates vomiting located

A

brain stem

10
Q

clinical features of vomiting

A
preceded by;
profuse salvation 
sweating 
elevated heart rate
sensation of nausea
11
Q

clinical features of vomiting

A
preceded by;
profuse salvation 
sweating 
elevated heart rate
sensation of nausea
12
Q

where is CTZ located

A

brainstem - lacks blood brain barrier

13
Q

where is NTS located

A

brainstem

14
Q

what drives the VC

A

central pattern generator (CPG) (which receives from NTS)

15
Q

consequences of loss of gastric protons and chloride

A

hypocholaemic metabolic alkalosis - raising of blood pH

16
Q

how is hypokalaemia mediated

A

via the kidney

proton loss accompanied by potassium excretion

17
Q

consequences of duodenal bicarbonate loss

A

metabolic acidosis

18
Q

antiemetic drugs

A
5-HT3 receptor antagonists 
muscarinic acetylcholine receptor antagonists  
histamine H1 receptor antagonists 
dopamine receptor antagonists 
NK1 receptor antagonists 
cannabinoid (CB1) receptor. agonists

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