Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Palliative Medicine > Vomiting > Flashcards

Vomiting Flashcards

1
Q

Where is the vomiting centre?

A

In the medulla

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

The vomiting centre receives impulses from 4 different pathways.

What are they?
How does it pick up these impulses?

A

GI tract

Vestibular apparatus

Higher centres

Chemoreceptor trigger zone

Picks up impulses from all these places via its muscarinic receptors on its surface

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Describe the steps in the process of GI tract problems causing vomiting.

A
  1. Enterochromaffin cells in the gastric mucosa release serotonin in response to irritation, cytotoxic agents etc.
  2. The serotonin binds to 5HT3 receptors of sensory nerves nearby
  3. These take signals via the vagus nerve to the muscarinic receptors of the vomiting centre
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Where is the chemoreceptor trigger zone?

A

In the medulla

It’s part of the vomiting centre

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Describe the steps in the process of cytotoxic agents causing vomiting.

A
  1. The CTZ is in the medulla but is located outside the blood-brain barrier
  2. It has 5HT3 and D2 receptors which detects biochemical upset in blood and CSF, caused cytotoxic agents
  3. When it detects these it sends an impulse to stimulate the muscarinic receptors of the vomiting centre
  4. This triggers the vomiting reflex
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Describe the steps in the process of emotion, pain, sights and smells causing vomiting?

A
  1. Brain processes emotion, pain, smell or sights
  2. The higher brain centre sends signals to the vomiting centre
  3. Which are picked up by the muscarinic receptors of vomiting centre
  4. Triggering the vomiting reflex
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Describe the steps in the process of vestibular problems causing vomiting.

A
  1. Vestibular apparatus sends signals about balance status to the vestibular nuclei in the pons
  2. The vestibular nuclei contains H1 and muscarinic receptors which pick up these signals from the v. apparatus
  3. The v. nuclei then sends signals to the CTZ’s D2 and 5HT3 receptors
  4. This then sends signals to the vomiting centre’s muscarinic receptors
  5. Which then triggers vomiting reflex
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Which neurotransmitters and corresponding receptors are involved in each vomiting pathway?

A

GI: Dopamine (D2), Serotonin (5HT3)

CTZ: Dopamine (D2), Serotonin (5HT3)

Higher: histamine (H1)

Vestibular: histamine (H1), Ach (muscarinic)

Substance P: Neurokinin 1 receptor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are some causes of each vomiting pathway?

  • GI tract
  • CTZ
  • Higher centre
  • Vestibular
A

GI tract: gastric irritation, gastric stasis, intestinal obstruction, cytotoxic agents in the stomach

CTZ: cytotoxic agents in blood (chemotherapy) electrolyte imbalance

Higher centre: smells, sights, emotion, pain, raised ICP

Vestibular: motion sickness, labyrinthitis, morning sickness

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Describe the steps in the process of raised ICP causing vomiting?

A
  1. Brain senses raised ICP
  2. The higher brain centre sends signals to the vomiting centre
  3. which are picked up by the muscarinic receptors of vomiting centre
  4. Triggering the vomiting reflex
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What happens when the vomiting reflex is triggered?

A

Relaxation of lower oesophageal sphincter

Contraction of diaphragm and abdominal muscles

Which results in raised intra-abdominal pressure

Epiglottis closes

Autonomic changes: tachycardia, salivation

Then vomit can be expelled

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are some non-pharmacological ways which can help reduce nausea and vomiting in a palliative patient?

A

Control odours from wounds, urine and faeces, food

Small snacks not large meals

Acupressure wrist bands

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Name the classes of anti-emetic drugs.

Give examples.

A

Histamine 1 receptor antagonists: cyclizine, promethazine

5HT3 receptor antagonists: ondansetron

D2 receptor antagonists:

  • Butyrophenones
  • Prokinetic agents
  • Phenothiazines

Muscarinic receptor antagonists: hyoscine

Neurokinin receptor antagonists

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Histamine 1 receptor antagonists.

Mechanism of action?

Which causes of N+V are they effective in?

Name some drugs.

A
  1. Block H1 receptors in the vestibular nuclei
  2. Preventing impulse getting from v. apparatus to v. nuclei
  3. Meaning no impulse gets from v, nuclei to CTZ to vomiting centre
  4. So no vomiting reflex triggered.

They are effective against vomiting caused by vestibular problem (motion sickness, morning sickness)

Cyclizine, promethazine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

5-HT3 receptor antagonists.

Mechanism of action?

Which causes of N+V are they effective in?

Name some drugs.

A
  1. Block 5HT-3 receptors on the CTZ so serotonin cannot bind. No impulse receieved by CTZ means no impulse sent from CTZ to vomiting centre
  2. Also block 5-HT3 in the nerves of the GI tract so serotonin cannot bind and send an impulse up to the vomiting centre
  3. No impulse received by vomiting centre means no vomiting reflex triggered

Effective against N+V caused by cytotoxic agents, drugs, electrolyte imbalances (uraemia)
AND
GI problems

Ondansetron, dolasetron

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

There are 3 different classes of D2 receptor antagonists.

What are they?
What are the differences in mechanism of action?

A

Phenothiazines:
Prochlorperazine, Chlopromazine
Reduces dopamine action in CTZ and other parts of brain

Pro-kinetics:
Metoclopromide (inhibits dopamine action in CTZ but stimulates gastric motility)

Butyrophenones: Haloperidol (inhibits dopamine action in brain)

17
Q

Muscarinic receptor antagonists.

Mechanism of action?

Which causes of N+V are they effective in?

Name some drugs.

A
  1. Inhibit muscarinic receptors on the vomiting centre
  2. So no impulses from any of the pathways can get to vomiting centre
  3. So vomiting reflex not triggered

Good for all types of vomiting

Hyoscine

18
Q

Histamine 1 receptor antagonists.

Example
Benefits
Side effects

A

Cyclizine

Benefits:
Good for motion sickness and morning sickness (vestibular pathway)

Side effects:
Drowsiness, sedation

19
Q

5-HT3 receptor antagonists.

Example
Benefits
Side effects

A

Ondansetron

Benefits:
Good for patients undergoing chemo, radiotherapy and for PONV

Side effects:
Headache, GI upset

20
Q

D2 receptor antagonists.

Example
Benefits
Side effects

A

Prochlorperazine
Metoclopramide

Benefits:
Good for patients undergoing chemo, radiotherapy
Reflux, hepato-biliary disorders

Side effect:
Sedation, HTN, Extra-pyramidal side effects

21
Q

What are the extra-pyramidal side effects?

A 
Akathasia
Oculogyric crisis
Tardive dyskinesia
Torticolis
Parkinsonism
Neuroleptic malignant syndrome.
22
Q

Muscarinic receptor antagonists.

Example
Benefits
Side effects

A

Hyoscine

Benefits: good for prophylaxis and motion sickness

Side effects: dry mouth, blurry vision, drowsiness

23
Q

Draw out how the 4 vomiting pathways link up with the vomiting centre.

A

https://www.youtube.com/watch?v=zD_CWMlrb5s

24
Q

Neurokinin receptor antagonists.

Mechanism of action?

Which causes of N+V are they effective in?

Name some drugs.

A
  1. Inhibit neurokinin 1 receptors which are found in the C and PNS
  2. Substance P cannot bind with NK1 receptors
  3. No impulse to vomiting centre

Effective in preventing chemotherapy induced N+V, no evidence on efficacy in treating established N+V

Aprepitant
Fosaprepitant

Palliative Medicine (4 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions