Anti-emetics Flashcards by Rdouble Rdouble

What do anticholinergic drugs do?

Anticholinergic drugs block and inhibit neurotransmitter activity

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Are anticholinergic drugs AGONISTS or ANTAGONISTS?

Anticholinergic drugs are ANTAGONISTS

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Which 4 things can act as emetic stimulus?

These 4 things can act as emetic stimulus:
*Toxins in food
*Abnormal Motion Vection
*Disease
*Side effect of therapy

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Why do people vomit?

Vomit is caused when balance and vision are out of sync. The body thinks it has been poisoned.

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What does VOMIT stand for?

VOMIT:
V: VESTIBULAR DISTURBANCE
O: OPIOIDS or OBSTRUCTION
M: MIND or MORNING SICKNESS
I: INFECTION or IRRITATION OF THE GUT
T: TOXINS and DRUGS

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What might be another trigger for vomiting?

Radiation therapy might be another trigger for vomiting particularly when it is 60-70% in the abdomen

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What are the 6 physiological consequences of chronic vomiting?

6 consequences of chronic vomiting:
* Dehydration
*Electrolyte imbalance
*Acid base imbalance
*Depression
*Aspiration
*Mallory-Weiss tears

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Where is the vomiting centre located?

The vomiting centre is located in the medulla oblongata of the brainstem

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What are enterochromaffin cells?
What do they do?

Enterochromaffin cells are:
*most common type of neuroendocrine cell in the GI tract
*90% of body’s serotonin is synthesized in EC cells

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What signals the release of mediators by enterochromaffin cells?

A potentially harmful substance in the stomach signals the release of mediators by enterochromaffin cells.

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Serotonin: Receptor? Receptor location? Antiemetic drug?

Serotonin:
*Receptor: 5-HT3
*Receptor location: Gastrointestinal tract (GIT), Chemoreceptor trigger zone (CTZ), Vomiting centre (VC).
*Antiemetic drug: Ondansetron (5-HT3 antagonist)

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Substance P: Receptor? Receptor location? Antiemetic drug?

Substance P:
*Receptor: NK1
*Receptor location: Chemoreceptor trigger zone (CTZ), Vomiting centre (VC)
*Antiemetic drug: Aprepitant (NK1 antagonist)

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Acetylcholine: Receptor? Receptor location? Antiemetic drug?

Acetylcholine:
*Receptor: M3 and M5
*Receptor location: Vestibular system, Nucleus tract solitarius (NTS), Vomiting centre (VC).
*Antiemetic drug: Aprepitant (NK1 antagonist)

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Dopamine: Receptor? Receptor location? Antiemetic drug?

Dopamine:
*Receptor: D2
*Receptor location: Chemoreceptor trigger zone (CTZ), Gastrointestinal tract (GIT).
*Antiemetic drug: Metoclopramide (D2 antagonist)

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Histamine: Receptor? Receptor location? Antiemetic drug?

Histamine:
*Receptor: H1
*Receptor location: Vestibular system, Nucleus tract solitarius (NTS)
*Antiemetic drug: Cyclizine (H1 antagonist)

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What are the key centres located in the brain medulla related to the Neuro-anatomy of vomiting?

Key centres: Vomiting centre (VC), Chemoreceptor trigger zone (CTZ), Nucleus tract solitarius (NTS)

What is the vomiting centre?

Vomiting centre: initiates and controls vomiting (emesis)

What is the chemoreceptor trigger zone (area postrema?

Chemoreceptor trigger zone:

What is the nucleus tract solitarius?

Nucleus tract solitarius:

Where is the chemoreceptor trigger zone located?

The chemoreceptor trigger zone is located on the “blood” side of the blood-brain barrier

What is serotonin (5HT)?

Serotonin (5 HT):
*Neurotransmitter
*Acts as a local hormone in the gut
* Neurotransmitter in the enteric nervous system

Where is 90% of the body’s serotonin synthesized?

90% of the body’s serotonin is synthesized in the endocrine ENTEROCHROMAFFIN CELLS in the mucosal layer lining the stomach and small intestine.

What kind of protein is the 5-HT3 receptor?

5-HT3 receptors are ligand gated cation channels.

Give 3 examples of 5-HT3 receptor antagonists

3 examples of 5-HT3 receptor antagonists: GraniseTRON, OndanseTRON, PalonesTRON

What type of antagonists are 5-HT3 receptor antagonists?

5-HT3 receptor antagonists are COMPETITIVE ANTAGONISTS

What are 5-HT3 receptors involved in?

5-HT3 receptors are involved in information transfer in the GI tract

What is the enteric nervous system?

Enteric nervous system: large part of the peripheral nervous system *controls gastrointestinal behaviour

What happens when sensory and vestibular information are imbalanced?

When sensory and vestibular information are imbalanced, motion sickness occurs.

What are Mallory-Weiss tears?

Mallory-Weiss tears are tears in the oesaphagus

Some of the causes of nausea and vomiting?

Nausea and vomiting causes: * Bacterial/viral infections * Migraine * Motion sickness * Pregnancy * Anxiety * Drugs

Which areas of the body can send vomiting signals to the vomiting centre?

* The higher cortical centres, solitary nucleus, chemoreceptor trigger zone and cerebellum can send direct signals to the vomiting centre. * Memory, sensory input do so indirectly via higher cortical centres. * The vestibular system (labyrinths in inner ear) do so indirectly via the cerebellum and chemoreceptor trigger zone. * The enterochromaffin cells from the GI tract send signals via the CTZ and solitary nucleus.

Why can the Chemoreceptor Trigger Zone (CTZ) detect chemicals, toxins and drugs?

The CTZ can detect chemicals, toxins and rugs due to the non typical blood brain barrier.