GI system → Monogastric and Ruminant stomach (test 1) Flashcards
what are the 3 critical factors for normal stomach function
- Patent pyloric outflow
- motility
- structural and functional integrity of mucosa
how is gastric motility controlled
Gastric motility is controlled through a balance of stimulatory and inhibitory inputs.
what stimulation and inhibition inputs aides in gastric motility
- Stimulation:
- Parasympathetic (vagal nerve)
- Gastrin
- Inhibition:
- Sympathetic nervous system
- Duodenal conditions
- <3.5 pH in duodenum
- peptides and amino acids
- osmolarity (hypertonicity)
- fatty acids
What is the function of G cells
G cells:
secrete gastrin→ ↑HCl secretion
↑ pepsinogen
↑motility
what is the function of parietal cells
H+ and Cl-
what is the function of mucous neck cells
precursor cells for
all the other epithelial types in the stomach
what is the function of enterochromaffin like cells
histamine → stimulate H2 receptor on parietal cells → ↑HCl
secretion
what is the function of chief cells
secrete pepsinogen → autoactivated at acid pH to pepsin, active enzyme
what is the gastric mucosal barrier
“Remarkably, this one cell layer of surface mucus-secreting cells is capable of
maintaining a BARRIER
• that keeps HCl acid and digestive enzymes contained within the lumen
AND
• prevents the loss of abnormal amounts of plasma constituents into the stomach.”
what are the 5 things that make up the gastric mucosal barrier
- Mucus (pH gradient)
- Bicarbonate secretion
- Epithelial barrier (tight junctions)
- Mucosal blood flow (subepithelial vasculature)
- Prostaglandins (e.g. pGI2)
what role do prostaglandins play in the gastric mucosal barrier
- a general protective effect on gastric mucosa
- stimulate secretion of bicarbonate into mucus layer
- helps maintain mucosal blood flow
what are some general signs of gastric dysfunction
- abdominal pain
- vomiting *
- melena
- anorexia
- anemia (bleeding)
- hematemesis
- weight loss
- bruxism (the involuntary or habitual grinding of the teeth, typically during sleep)
- ptyalism (an excessive flow of saliva)
what are some triggers that stimulate emesis
- Chemoreceptor trigger zone
- toxins, drugs, ketoacidosis, uremia, etc.
- GI Tract
- distention / obstruction, mucosal perturbation
- Outside GI Tract
- bile duct, peritoneum
- Extramedullary brain centers
- certain odors, fears, motion
what are the 3 potential consequences of vomiting
- dehydration / hypovolemia
- metabolic imbalances
- aspiration pneumonia
what are some metabolic imbalances that can stem from chronic emesis
- alkalosis (severe pyloric or high duodenal obstruction)
- hypochloremia
- hypokalemia
what are some clinical signs for gastric outflow obstruction
(a) post-prandial dilation and vomiting
(b) vomiting - poorly digested
(c) vomiting may be chronic & associated with weight loss
(d) horses - reflux when pass stomach tube
(e) full stomach on radiographs – despite Hx
what are the most common / important neoplasms that occur as intraluminal or intramural gastric masses.
- Adenocarcinoma
- account for 60-70% of gastric neoplasms in the dog
- Leiomyoma
- typically adiscrete solitary intramural lesion (benign)
- Lymphosarcoma
- most common gastric malignancy in cats and #2 in dogs
- SCCa
- important DfDx for chronic weight loss in horses
- Polyps
- benign mucosal lesions occuring in both dogs and cats
what is the most common gastric neoplasm in dogs
Adenocarcinoma → account for 60-70%
followed by lymphosarcoma
what is the most common gastric neoplasm in cats
lymphosarcoma
in the event of chronic weight loss in a horse, what gastric neoplasm should make your DfDx
SCCa
a GDV (Gastric Dilatation w/ Volvulus is a true surgical emergency in our canine friends. What are some telltale signs of thie problem?
Signs = rapid gaseous distention of stomach
- abdominal distention & pain
- tachycardia
- restlessness / depression
- shallow breathing
- pale mucous membranes
- weak peripheral pulses
- retching = non-productive vomiting
- inability to pass a stomach tube
Please describe what is shown in the image
this is a simple Gastric Dilatation