GI & Pancreas Flashcards
Reasons for anorexia for D2 post-op splenectomy:
- Lack of gastrocolic reflex
- Lack of motilin stimulation (by fat)
- Lack of CCK stimulation (by protein)
- Peritoneal inflammation -> decrease slow waves => NO production
- Opioids interrupting MMC
- Pain (?)
What are the 4 phases of MMCs?
I. Period of quiescence
II. ↑ AP and smooth muscle activity
III. Peak electrical activity and mechanical activity (lasts 5-10 minutes)
IV. Declining activity that leads back to phase I
Functions of the MMC are interrupted by:
Meals
Drugs: narcotics, atropine, alpha-2 agonist
Stress
Bacterial toxins e.g. Campy CdtB toxin
Main role of myenteric plexus:
Stimulation increases peristalsis
Main role of submucosal plexus:
Help with mixing: local segmental intestinal secretion, absorption and contraction of submucosal muscle
Gastrin
Stimuli for secretion
Site of secretion
Action
Stimuli for secretion:
- Protein
- Gastric distention
- (Acid inhibits release)
Site of secretion: G cells (located in: stomach, duodenum)
Actions:
Stimulates:
- Gastric acid secretion (parietal cells)
- Stimulates pepsinogen (chief cells)
- Mucosal growth/repair
Cholecystokinin
Stimuli for secretion
Site of secretion
Action
Stimuli for secretion:
Protein
Fat and its byproducts
Acid
Site of secretion: I cells (duodenum, jejunum, ileum)
Actions:
Stimulates:
- Pancreatic enzymes + bicarb secretion
- GB contraction to digest fat
- Relaxation of sphincter of Oddi
- Growth of exocrine pancreas
Inhibits:
- Appetite
- Gastric acid secretion
- Gastric emptying: gives time for digestion
Gastric Inhibitory Peptide (GIP)
Stimuli for secretion
Site of secretion
Action
Stimuli for secretion:
PROTEIN
Fat
Carbohydrate
Site of secretion: K cells (duodenum + jejunum)
Actions:
Stimulates: insulin release
Inhibits:
- Gastric acid secretion
- Gastric emptying
Vasoactive Intestinal Peptide (VIP)
Site of secretion
Main action
Site of secretion: enteric nerves
Main action
- increase water + electrolyte secretion from pancreas & gut
- relaxes smooth muscle (via NO)
Motilin
Stimuli for secretion
Site of secretion
Action
Stimuli for secretion: FAT
Acid
Nerve
Site of secretion: M cells & ECL cells (throughout)
Actions:
Stimulates:
- Gastric motility
- Intestinal motility
Secretin
Stimuli for secretion
Site of secretion
Action
Stimuli for secretion: Acid
Fat
Site of secretion: S cells (duodenum, jejunum)
Actions:
Stimulates:
- Pepsin secretion
- Pancreatic & biliary bicarb secretion
- Growth of exocrine pancreas
Inhibits: gastric acid secretion
Somatostatin
Stimuli for secretion
Site of secretion
Action
Stimuli for secretion: acid
Site of secretion: D cells (pancreatic islets, stomach, SI)
Actions: Inhibits:
- Secretion of: gastrin, VIP, GIP, secretin and motilin
- Pancreatic exocrine secretion
- Gastric acid secretion
- Gastric motility
- GB contraction
Absorption of aa and triglycerides
Ways to help improve motility:
- Drugs
- Early ambulation
- Early controlled enteral nutrition
- Multi-modal analgesia
- GIT decompression
- Judicious IVFT to limit bowel oedema
4 functions of the exocrine pancreas:
Acinar cells secrete:
1) zymogens (digestion)
2) antibacterial proteins (regulate SI flora)
Ductal cells secrete:
1) bicarb + water to neutralise duodenal pH
2) pancreatic intrinsic factor (aid with B12 handling in distal ileum)
What are the pathophysiologic mechanisms of diarrhoea? (4)
1) Osmotic diarrhoea -Excess luminal osmoles drawing fluid into the intestinal lumen
2) Secretory diarrhoea - Net increase in intestinal fluid secretion. either through ↑secretion or ↓absorption
3) altered permeability - Mircoscopic/macroscopic damage to epithelial cells or their junctions. Risk of translocation of bacteria
4) Deranged motility -
Either ↑ peristaltic contractions or ↓segmental contractions
Risk factors for R&A site breakdown
- pre-op peritonitis
- intestinal FB
- serum albumin < 25g/L
- intra-op hypotension
Define primary peritonitis
spontaneous inflammatory condition in absence of underlying intrabdominal pathology
define secondary peritonitis
consequence of preexisting septic or aseptic pathologic intraabdominal condition
define tertiary peritonitis
recurrent or persistent intra-abdominal infection after previous surgical and antimicrobial therapy for secondary bacterial peritonitis
recommended lavage volume for septic peritonitis
200-300mL/kg
Pattern of gastric necrosis in GDV:
Fundus -> body
why do ventricular arrhythmias occur in 40% of GDV cases?
- Coronary blood flow reduced by 50% (experimentally), myocardial ischemia – may establish ectopic foci of electrical activity
- Circulating cardiostimulatory substances – epinephrine
- Circulating cardioinhibitory substances – pro-inflammatory cytokines (TNF-a, IL-1)
What lactate level makes gastric necrosis more likely in GDV?
> 6
Higher survival associated with lactate < ____ in GDV?
4
