Nausea and Vomiting Flashcards
What structure initiates, regulates and controls the act of vomiting and where is it located?
The vomiting centre initiate, regultes and contorls vomiting and is located in the medulla oblongata of the brainstem.
How does the vomit centre contorl the act of vomiting?
The vomit centre has muscurinic receptors on the osutide which send impulses to the muscle that act during vomiting.
When would you give a 5HT Blocker as an antiemetic?
If a patient is suffeing from Post op Nausea and Vomiting ( PONV), nausea associated with chemotheapy and radiation therapy.
Why would you give Seratonin Blocker antiemetics after Chemotherapy, surgery o radiation?
During these events seratonin levels increase and can cause severe nausea and vomiting. Seratonin blocker antiemetic will block the recpetors at the chemoreceptor trigger zone stopping the signal being sent to the vomit centre.
What are some side effects of Seratonin blocker antiemetics?
headache, dizziness, myalgia ( muscle pain/cramping), urinry retention, hypotension,
When would you give Dopamine 2 Antagonists?
Nausea and vomiting associated with general anaesthetics, opioids and cytotoxic drugs.
What is an example of a Seratonin Blocker antiemetic?
Odansetron
What is an example of a Dopamine 2 Blocker antiemetic?
Metaclopramide
What are some side effects of Dopamine 2 blocker antiemetics?
drowziness, dizziness, headache, weakness, temors, photosensitivity
What would you give someone suffering from motion sickness as an antiemtic?
Antihistamine to block the Histamine recptors stopping signals being sent to the vomit centre.
Where is the CTZ located and what does this mean?
In the medulla oblongata OUTSIDE the Blood Brain Barrier (BBB).
This means that is is more permeable to curclutaiong toxins eg chemo, drugs, alcahol etc and can easily activae the vomite centre.
What two receptors sit on the CTZ?
Dopamine 2 and 5HT ( Seratonin)
Describe the process of nausea and vomiting due to motion sickness?
In the inner ear, the labrynth and cochlea are housed. Motion sickness abnorally activates the cochealr nerve which connects to vestibular nuceli in brainstem. They have muscurininc receptors and histamine receptors on the outside which, when stimulate by the cochlear nerve sends signals to the CTZ and therefore the vomit centre.
What are higher senses and how do they make a person vomit?
Higher senses are things such as ain, smell, tatse and memory.
Afferent impulses from higher centre of brain are sent straight to the vomit centre .
How does the stomach contribute to nausea and vomiting?
98% of the bodies Seratonin is foun in the stomach
Vagal senspry nerve fibres also cause vomiting straight from stomach relating to food that could agrivate the stomach lining and GI tract.
Contraction of abdominal muscles casues food to move upwards and into GI tract which relaxes allowing food to be expelled upwards.
