Phys Exam 3 - Dr. Bryan

What is emesis?

vomiting

What is a complex reflex pathway that protects animals from ingested toxins?

emesis

What are the two pathways of the Borison and Wang model of vomiting?

humoral and neural

What does the humoral pathway activate with blood borne substances?

chemoreceptor trigger zone

What activates the chemoreceptor trigger zone in the humoral pathway?

blood borne substances

What is activated by the vagosympathetic, chemoreceptor trigger zone, nucleus tractus soliarius, vestibular, or cerebrocortical neurons in the neural pathway?

emetic center

What Borison and Wang pathway is the activation of CRTZ by blood born substances?

humoral pathway

What Borison and Wang pathway activates the emetic center by the vagosympathetic, chemoreceptor trigger zone, nucleus tractus soliarius, vestibular, or cerebrocortical neurons in the neural pathway?

neural pathway

What does the humoral pathway activate?

CRTZ

What does the neural pathway activate?

emetic center

What are the endogenous causes of the humoral pathway?

uremia, hepatoencephalopathy, and endotoxins

What are the exogenous causes of the humoral pathway?

digoxin, apomorphine, cisplatin

Where is the chemoreceptor trigger zone (CRTZ) loacted?

bilaterally in the 4th ventricle

What is the “hole” in the blood brain barrier?

chemoreceptor trigger zone

T/F CRTZ readily perfuses substances in systemic circulation

TRUE

Is the neural pathway afferent or efferent?

afferent

What pathway has something to do with primary GI tract disease?

neural pathway

What is the synapse for motion within semicircular canals that is transduced to vestibulocochlear neurons in dogs?

CRTZ

What is the synapse for motion within semicircular canals that is transduced to vestibulocochlear neurons in cats?

emetic center

What in the neural pathway is activated from anxiety and anticipation?

cerebrocortical neurons

What synapse in dogs is what causes motion sickness?

CRTZ

What synapse in cats is what causes motion sickness?

emetic center

What does motion within the semicircular canals that is transduced to vestibulocochlear neurons cause?

motion sickness

What does activation of afferent neural pathway, nucleus tractus solitarius neurons and emetic center cause?

primary GI tract disease

What pathway is motion sickness associated with?

neural pathway

What pathway is anxiety and anticipation associated with?

neural pathway

What pathway is primary GI tract disease assocaited with?

primary GI tract disease

What nerves do motor impulse run from the brain to the upper GI tract?

5, 7, 9, 10, 12

What is the prelude to vomiting?

anti-peristalsis

What is the most distal part of the GI tract that can do antiperistalsis waves?

ileum

How fast does digesta travel backwards?

2-3 cm/sec

How fast do SI contents move up to the duogenum and stomach?

3-5 mins

What provides the trigger for vomiting?

gastric and duodenal distention/irritation

What must relax for vomiting to occur?

lower esophageal sphinter

What raises to to allow for vomitting?

hyoid bone, larynx, soft palate

What must close for vomiting to properly occur?

glottis

What are abdominal, gastrointestinal tract causes of vomiting?

obstruction, intussusception, foreign bodies, inflammation, motility disorders, ulceration, infection. malignancy, and toxicity

What are the metabolic causes of vomiting?

uremia, liver failure, electrolyte distrubances, acid-base disorders

What are the abdominal, outside gastrointestinal tract causes of vomiting?

peritonitis, urinary tract rupture, pyometra, and splenitis

What are endocrine causes of vomiting?

diabetes mellitus, hyperthyroidism, and hypoadrenocorticism

What are the systemic disorders that can cause vomiting?

septicemia, endotoxemia, multiple organ failure

What are the exogenous medications that can cause vommiting?

digoxin, erythromycin, apomorphine, ropinirole, xylazine, NSAIDs, chemotherapeutics

What chemotherapeutics can cause vomiting?

cisplatin, doxorubicin, cyclophosphamide

What nervous system issues that can cause vomiting?

encephalitis, meningitis, hydrocephalus, head trauma

What toxicity can cause vomiting?

ethylene glycol, strychnine. and heavy metals

What heavy metals can cause vomiting?

Cu, Zn, and Pb

How do impulses travel from the vestibular labyrinth of the inner ear to the cerebellum?

vestibular nuclei

Where in the cerebellum is the vomiting zone that receives signals from the vestibular nuclei in motion sickness?

chemoreceptor trigger zone

What center does the chemoreceptor trigger zone trigger?

vomiting center

What are important in signaling for survival of dopamine neurons and neuronal development?

D2 dopamine receptors

What provides signaling path for catecholamines like norepinephrine and epinephrine?

a2-adrenergic receptors

What are the types of histamine?

H1 and H2

What receptors aid in converting 5-hydroxytryptamine (serotonin) to monoamine neurotransmitter?

5-HT3

In what species are CRTZ D2-dopamine receptors important for humoral emesis?

dogs

In what species is a2 adrenergic stimulation important?

cats

What receptors induce emesis with chemotherapeutics in dogs?

visceral and vagal 5-HT3

What receptors induce emesis with chemotherapeutics in cats?

5-HT3 in CRTZ

What species has H1 and H2 hisaminergic receptors in CRTZ?

Dogs

What is the only FDA-approved veterinary emetic?

Ropinirole aka clevor

What species is ropinirole a potent emetic?

dogs

What receptor does ropinirole act as an agonist on?

D2-dopamine

What receptor does Apomorphine act as an agonist on?

apomorphine

In what species is apomorphine a potent?

dog

What are the two emetics for dogs?

ropinirole and apomorphome

What are the two emetics in cats?

xylazine and dexmedetomidine

What receptor does xylazine act as an agonist on?

a2-adrenergic

In what species is xyazine a potent emetic?

cats

What receptor does dexmedetomidine act as an agonist on?

a2-adrenergic

To what species is dexmedetomideine a potend emetic?

cats

What are the two products that can induce vomiting at home?

hydrogen peroxide and syrup of ipecac

How does hydrogen peroxide do to induce emesis?

irritant of oropharynx and gastic lining

How does syrup of ipecac induce emesis?

irritant of gastric lining and CRTZ

Does hydrogen peroxide work to induce emesis in cats?

sometimes

What 4 drugs can control vomiting?

maropitant citrate, metroclopramide, ondansetron, and meclizine

What is the only veterinary labeled anti-emetic?

Maropitant citrate (cerenia)

What does maropitant citrate antagonize?

neurokinin receotor

When maropitant citrate antagonizes neurokinin receptors, what does it block?

substance P

What parts of the humoral and neural pathway does maropitant citrate affect?

CRTZ and emetic

What receptor does Metoclopramide anatagonize?

D2-dopamine

What parts of the humoral/neural pathway does metocloprimade affect?

CRTZ

What does metoclopramide do to GI smooth muscle?

increase motility

What receptor does ondansetron antagonize?

5-HT3

What part of the pathways does ondanseteron affect?

CRTZ and vagal afferent neurons

What receptor does meclizine (dramamine) antagonize?

muscarinic cholinergic

What part of the pathway does meclizine affect?

CRTZ

How does the humoral pathway happen?

CRTZ activation

How does the neural pathway happen?

emetic center activation

What are the etiologies of emesis?

diesase process, pharmacologically associated, and medically induced

When is the only time you shouldn’t do a rectal exam?

if there is not butthole