Physiology/Pathophysiology Flashcards
What are the primary actions of gastrin?
Stimulation of gastric acid secretion
Stimulation of mucosal growth
How does gastrin stimulate gastric acid secretion?
Causes the release of histamine from the enterochromaffin-like cells of the stomac by direct action on the parietal cells.
What are the primary actions of CCK?
Stimuation of pancreatic HCO3 secretion
Stimulation of pancreatic enzyme secretion
Stimulation of gallbladder contraction
Stimulation of pancreatic growth
Inhibition of gastric emptying
What are the primary actions of secretin?
Stimulation of pancreatic fluid and bicarbonate secretion
Stimulation of biliary secretion of fluid and bicarbonate
Potent inhibition of gastric acid secretion
What enzyme is the most potent regulator of gallbladder contraction?
CCK
What enzyme is the most potent choleretic?
Secretin
What do chief cells secrete?
What do parietal cells secrete?
Chief cells secrete pepsinogen
Parietal cells secrete HCl
What are the 3 phases of gastric acid secretion?
Cephalic (Ach and GRP responsible for acid release; vagal stimulation initiates)
Gastric (peptides, amino acids stimulate gastrin release from G cells; rise in pH
Intestinal (protein digestion products in duodenum stimulate acid secretion)
What are the two components of pancreatic exocrine secretion? What is the purpose of each of these components?
- Aqueous/bicarbonate compnent
- Function is neutralization of duodenal contents, preventing damage to the duodenal mucosa by acid and pepsi and brings the pH of the contents back into optimum range for activity of pancreatic enzymes
- Enzymatic/protein component
- Low volume secretion containing enzymes for digestion
What determines/regulates secretion during the two phases of exocrine pancreatic secretion?
- The aqueous component (secretion of fluid and HCO3) is largely determined by the amount of acid entering the duodenum
- Secretion of pancreatic enzymes is primarily determined by the amount of fat and protein entering the duodenum
- Regulated primarily by secretin, CCK and vasovagal reflexes
- Intestinal stimuli most important
What are thecriteria for diagnosis of an acute abdomen based on:
Blood glucose versus peritoneal glucose
Peritoneal lactate versus blood lactate
Fluid to blood potassium ratio
Fluid to blood creatinine ratio
Fluid to blood bilirubin ratio
Blood glucose minus peritoneal glucose: >20mg/dL difference
Peritoneal fluid lactate minus blood lactate: >2.0mmol/L difference
Fluid to blood potassium ratio: Dogs=1.4:1, Cats=1.9:1
Fluid to blood creatinine ratio: Dogs=2:1, Cats= 2:1
Fluid to blood bilirubin ratio: >2:1
Briefly describe the pathogenesis of acute pancreatitis.
- Intrapancreatic activation of digestive enzymes with resultant pancreatic autodigestion
- Initial events within the acinar cell with abnormal fusion of normally segregated lysosomes with zymogen granules
- Results in premature activation of trypsinogen to trypsin
- Trypsin activates other proenzymes, leading to local and systemic effects
- Trypsin can activate copmlement cascade, and kallikrein-kinin system, and coagulation/fibrinolytic pathways
- Local ischemia, PLA2 and ROS disrupt cell membranes, leading to pancreatic hemorrhage and necrosis, increased capillary permeability and initation of arachidonic acid cascade
Explain the change in PCV/TS seen in patients with HGE.
Rise in PCV with either no change or a drop in TS.
PCV rises because of hemoconcentration and/or splenic contraction
TS doesn’t change/drop due to GI loss of serum proteins or redistribution of body water into the vascular space
What are causes of acquired megaesophagus?
What breeds are predisposed to developing this condition?
- Majority of cases are idiopathic; myasthenia is the most common cause if cause can be identified
- Also hypoadrenocorticism, lead/thallium poisoning, lupus, esophageal neoplasia and severe esophagitis
- GSD, Goldens, Iris Setters, Abyssinians and Somali cats
What are the most commonly reported risk factors for ulcers in dogs?
NSAIDS and hepatic disease
