GI tract Flashcards
Functions of gastrointestinal (GI) system (3)
Intake of food and fluid into the body
◦ Absorption of nutrients and fluid
◦ Excretion of waste products
Ruminant animals are herbivorous and have a GI system characterized by:
Three forestomachs, the reticulum, rumen, omasum, and a “true” stomach
Equines, rabbits, and some rodents are chiefly herbivorous animals that have a monogastric GI configuration and are considered
hindgut fermenters
Regulation of GI system activity is complex but can be said to be under influence of following three basic control systems
- Autonomic nervous system (ANS)
- Gastrointestinal hormones such as gastrin, secretin, and cholecystokinin
- Substances such as histamine, serotonin, and prostaglandin are released from specialized cells of GI tract
Emetics
Drugs that induce vomiting
Emetics are administered
to animals that have ingested toxins;
(Emetics) When not to induce vomiting:
acid/base
altered mentation
species that cannot vomit
Antiemetics
Drugs that are used to prevent or control vomiting
Antiemetics will block
receptors centrally in the CRTZ, emetic center, and peripheral receptors
Subcategory of Emetics
Local and central acting
MOA of Emetics Central
stimulation of CRTZ
MOA of Emetics local
local irritation
Uses for Emetics central
Know when not to use
Adverse effect emetics central
prolonged vomiting
Adverse effect emetics local
severe gastritis, aspiration
Subcategory of Antiemetics (5)
- phenothiazine
- Procainamide
- Antihistamine
- serotonin antagonist
- NK-1 Receptor antagonist
phenothiazine MOA
blocking dopamine receptors in the CRTZ and possibly by direct inhibition of the vomiting center
Phenothiazine USE
preventing motion sickness in dogs/cats
Phenothiazine side effects
Hypotension and sedation and ataxia
Procainamide Derivative MOA
block dopamine on CRTZ & increases gastric contraction, speeds emptyping, increases
peristalsis of the small intestine, relax pyloric sphincter
Procainamide Derivative USES
prevent motion sickness
Procainamide Derivative ADVSERSE EFFECTS
CNS or behavioral changes /contraindicated with GI obstruction (constipation)
Antihistamines (H1 blockers) MOA
block histamine-1 in CRTZ
Antihistamines are most effective as ___ in dogs/cats when vomiting is a result of motion sickness and
Antiemetics
Inner ear abnormalities
Antihistamines (H1 blockers) ADVERSE EFFECT
sedation
serotonin antagonist MOA
Blockade of 5-HTR
serotonin antagonist USE
chemotherapy; severe vomiting
NK-1 Receptor Anatagonist MOA
Blocks binding of substance P to
Neurokinin-1 R in CRTZ
NK-1 Receptor Anatagonist USES
Vomiting from motion sickness/ acute
NK-1 Receptor Anatagonist ADVERSE EFFECT
diarrnea, anorexia, increase salivation
Gastric ulcers may occur in animals for what reasons (4)
stress
metabolic disease
gastric hyperacidity
Drug therapy
Subcategory for Antiulcer and Antacids (5)
- H-2 Receptor antagonists
- proton pump inhibitor
- Antacids
- Gastromucosal protectants
- Prostaglandin E1 analogues
H-2 Receptor antagonists MOA
H2 blockers - reduces HCl acid release by parietal cells
Vomiting
Forceful ejection of the contents of the stomach, and sometimes the contents of the proximal small intestine
Vomiting center (emetic center) is connected by nerve pathways to the
chemoreceptor trigger zone (CRTZ)
Multiple neurotransmitters are involved in the
vomiting reflexes
H-2 Receptor antagonists Uses
prevention of gastric, abomasal or duodenal ulcers; gastric reflux
H-2 Receptor antagonist Adverse effect
some slow metabolism of other drugs
proton pump inhibitor MOA
bind irreversibly to Na-K-ATPase enzyme of parietal cells; preventing HCl release
Proton pump inhibitor Uses
treat gastric or duodenal ulcers, and esophattis
Proton pump inhibitor Adverse effect
constipation, sedation, ileus, pancreatitis, CNS effects
