GI

Question 1

Foregut, midgut, hindgut

Answer 1

• foregut= pharynx to duodenum (supplied by Celiac a)
  
  • liver, gallbladder, pancreas and spleen also supplie
• midgut = duodenum to proximal 2/3 transverse colon (supplied by SMA)
• hindgut = rest of colon to anal canal above pectinate line (IMA)
  
  • splenic flexure = watershed zone
• off abdominal aorta: celiac trunk, SMA and IMA branch anteriorly

Question 2

Retroperitoneal structures

Answer 2

• SAD PUCKER
• Suprarenal (adrenal) glands
• Aorta (and IVC)
• Duodenum (2-4th parts)
• Pancreas (except tail)
• Ureters
• Colon (ascending and descending)
• Kidneys
• Rectum

Question 3

1. Falciform ligament
2. Hepatoduodenal
3. Gastrohepatic
4. Gastrosplenic
5. Gastrocolic
6. Splenorenal

Answer 3

1. contains ligamentum teres hepatis (remnant of umbilical vein) – connects liver to ant abd wall
2. contains portal triad (proper hepatic a, portal vein, common bile duct)
3. contains gastric aa (connects liver to lesser curvature)
4. contains short gastrics and L gastroepiploic vessels – connects greater curvature and spleen
5. contains gastroepiploic aa (connects greature curvature to tranverse colon)
6. contains splenic a and v, tails of pancreas (connects spleen to posterior abdominal wall)

Question 4

layers of gut wall

Answer 4

• Mucosa: epithelium, lamina propria, muscularis mucosa
• Submucosa: Meissner plexus
• Muscularis externa: Inner circular and outer longitudinal layer with Myenteric nerve plexus (Auerbach)
• Serosa/Adventitia

MSMS

Question 5

Celiac Trunk

Answer 5

• branches of celiac trunk
  
  1. common hepatic
     
     • divides into proper hepatic a (to liver) and gastroduodenal a –> R gastroepiploic and pancreaticoduodenal aa
  2. splenic
     
     • direct branches to spleen and pancreas
     • L gastroepiploic a
     • short gastric branches (to fundus of stomach)
  3. L gastric (lesser curvature of stomach)
     
     • gives off esophageal branch

L+R gastroepiploics anastomose along greater curvature of stomach; L and R gastrics anastomose along lesser curvature

Question 6

indirect vs direct inguinal hernias

Answer 6

• MDLI (MD’s dont LIe)
• direct: medial to inferior epigastric a – protrudes through Hesselbach triangle –> goes through superficial/external inguinal ring only
  
  • acquired in older men
• indirect: lateral to inferior epigastric a – goes through deep/internal and external/superficial ring and scrotum
  
  • congenital: failure of processus vaginalis to close
• Femoral hernias protrude underneath inguinal ligament through femoral canal (leading cause of bowel incarceration)

Question 7

1. CCK
2. Gastrin
3. GIP

Answer 7

1. I cells in duodenum and jejunum – increase pancreatic secretion, gallbladder contraction, gastric emptying
   
   • regulated by FA and AA
2. G cells (antrum of stomach) – increase H+ secretion, growth of gastic mucosa, gastric motility
   
   • regulated by stomach distention, alkalinization, AA, peptides, vagal stimulation
3. K cells (duodenum, jejunum) – decrease H+ secretion, increase insulin secretion
   
   • regulated by FA, AA, glucose (oral glucose load used more than equivalent given by IV)

Question 8

1. Motilin
2. Secretin
3. Somatostatin

Answer 8

1. SI – produces migrating motor complexes in fasting state
2. S cell of duodenum – increased pancreatic bicarb, decrease gastric H+, increased bile secretion
   
   • regulated by acid, FA in duodenum
3. D cells of pancreatic islets and GI mucosa – decrease gastric H+, decrease pancreatic and SI fluid secretion, decrease gallbladder contraction, decrease insulin and glucagon release (anti-growth hormone effects)
   
   • regulated by increased acid and decreased vagal stim

Question 9

1. NO
2. VIP
3. IF

Answer 9

1. increase smooth mm relaxation – loss of NO secretion implicated in achalasia
2. PS ganglia in sphincters, gallbladder and SI – increases intest water and electrolyte secretion, increase relaxation of intest smooth mm and sphincters
   
   • regulated by distension and vagal stimulation
3. parietal cells in stomach – Vit B12 binding protein

Question 10

1. gastric acid
2. Pepsin
3. HCO3-

Answer 10

1. Parietal cells in stomach
   
   • up-regulated by HA, ACh, gastrin; downregulated by somatostatin, GIP, PGE and secretin
2. Chief cells in stomach – protein digestion
   
   • upregulated by vagal stimulation and local acid
3. mucosa cells (stomach, duodenum, salivary glands, pancreas) + Brunner glands (duodenum)
   
   • upregulated by pancreatic and biliary secretion with secretin

Question 11

1. H2 blockers
2. PPI
3. Octreotide
4. Misoprostol

Answer 11

1. Cimetidine, ranitidine, famotidine
   
   • cimetidine potent inhibitor of P450 + has antiandrogenic effects
2. Omeprazole, lansoprazole, pantoprazole
3. somatostatin analog – use for acute variceal bleeds, acromegaly, VIPoma and carcinoid tumors
4. PGE1 analog – prevention of NSAID-induced peptic ulcers

Question 12

antacids

Answer 12

1. aluminum hydroxide – constipation (mininimus feces)
2. calcium carbonate – hypercalcemia and rebound acidity
3. magnesium hydroxide – diarrhea (Mg= must go)

Question 13

osmotic laxatives

Answer 13

1. magnesium hydroxide
2. magnesium citrate
3. polyethylene glycol
4. lactulose (also treats hepatic encephalopathy – gut flora degrade it into metabolites that promote N excretion as NH4+

use to tx constipation: provide osmotic load to draw water out

Question 14

1. Infliximab
2. Sulfasalazine
3. Ondansetron
4. Metoclopramide

Answer 14

1. mAb to TNF-alpha – tx Crohn’s, ulcerative colitis, RA, ankylosing spondylitis, psoriasis — risk of reactivation of latent TB
2. combo of sulfapyridine (antibacterial) and 5-ASA (anti-inflamm) – tx Crohn’s and ulcerative colitis
3. 5-HT3 antagonist – central acting antiemetic (decrease vagal stimulation)
4. D2 receptor antag –> increases resting tone, contractility, LES tone and motility – use for diabetic and post=surgery gastroparesis
   
   • Parkinosism SE (D antagonism)