NURS 2050 Lecture Notes - Chemoreceptor Trigger Zone, 5-Ht3 Receptor, Vestibular System
11 Apr 2013
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Document Summary
Antimetics: drugs that are effective against nausea and vomiting. Direct stimuli = signals from cerebral cortex (fear), sensory organs, vestibular apparatus in the inner ear. Indirect stimuli = activate the chemoreceptor trigger zone (ctz) -- in turn activates vomiting centre: signals from the stomach vagal afferents, direct actions of drugs and chemicals. Chemotherapy induced nausea & vomiting: anticipatory triggers memory or past experiences, acute few minutes after chemo begins, delayed a day or 2 later. Knowledge of highly emetogenic regimens are available and antiemetics are chosen based on this. Receptors important for nausea & vomiting: serotonin. Receptors located in the upper gi and chemo receptor trigger zone (5ht3) Receptors located in the upper gi and ctz. Useful for n/v from chemotherapy: block d2 receptors in the ctz, metoclopramide (high dose) = 5ht3 receptor blocker. Hypotension: acetylcholine, muscarinic antagonists (scopolamine, used for motion sickness, suppress neuronal traffic from vestibular apparatus to vomiting centre.
