Gastrointestinal Tract

Question 1

What GI organs are part of the ‘foregut’?

Answer 1

• Esophagus
• Stomach
• Liver
• Duodenum (1st and 2nd segments)
• Gallbladder
• Superior portion of Pancreas

Question 2

What GI organs are part of the ‘midgut’?

Answer 2

• Duodenum (3rd and 4th segments)
• Jejunem
• Ileum
• Cecum
• Appendix
• Ascending Colon
• Hepatic Flexure of Colon
• Transverse Colon (Proximal 2/3)

Question 3

What GI organs are part of the ‘hindgut’?

Answer 3

• 1/3 of Transverse Colon and Splenic Flexure
• Descending Colon
• Sigmoid Colon
• Rectum
• Upper part of Anal Canal

Question 4

What are the six steps of the digestive process? What are some of their landmarks?

Answer 4

Ingestion

Propulsion
- Peristalsis

Mechanical Digestion

• Churning
• Segmentation

Chemical Digestion

Absorption

Defecation
- borborygmi (bowel sounds)

Question 5

What are the two divisions of the Peritoneum? What comprises each divison?

Answer 5

Ventral Peritoneum

• Falciform Ligament
• Lesser Omentum

Dorsal Peritoneum

• Greater Omentum
• Mesentery Proper
• Transverse Mesocolon

Question 6

What organs are each of the Peritoneal folds associated with?

Answer 6

Greater Omentum - Stomach (greater curvature)
Lesser Omentum - Stomach (lesser curvature)

Mesentery Proper - Small Intestine
Transverse Mesocolon - Colon (Transverse)

Question 7

What ligaments does the Lesser Omentum give off? Which is a danger structure and why?

Answer 7

Hepatogastric Ligament
Hepatoduodenal Ligament
- Danger! Contains the PORTAL TRIAD (Common Hepatic Artery, Common Bile Duct, Hepatic Portal Vein))

Question 8

What is unique about the stomach among the GI Tract organs?

Answer 8

It has 3 layers of smooth muscle instead of the usual 2. This is to facilitate the churning/blending motion of the stomach to break down food mechanically before it undergoes chemical digestion.

Question 9

What is chyme?

Answer 9

Food that has been ‘blended’ into a liquid mixed with gastric juices.

Question 10

Name the three major sections of the stomach.

Answer 10

Fundus, Corpus, Pylorus

Question 11

What feature of the stomach is variable and what triggers that variability?

Answer 11

Rugae (Gastric Folds)

- These folds only exist when the stomach is not full. When it IS full, the rugae will stretch out and disappear.

Question 12

Give the three main branches of the Celiac Trunk.

Answer 12

Left Gastric Artery

Common Hepatic Artery

Splenic Artery

Question 13

What branches does the Common Hepatic Artery give off?

Answer 13

Right Gastric
Gastroduodenal
- Branches into Right Gastro-omental and Superior Pancreaticoduodenal Arteries

Note: After giving off the Gastroduodenal Artery, the Common Hepatic Artery becomes the Proper Hepatic Artery.

Question 14

What branches does the Left Gastric Artery give off?

Answer 14

None. It moves to the Lesser Curvature of the stomach and anastamoses with the Right Gastric Artery.

Question 15

What branches does the Splenic Artery give off?

Answer 15

Left Gastro-omental
Short Gastric
(Splemic Branches?)

Question 16

What branches come off of the Proper Hepatic Artery?

Answer 16

Cystic Artery

Right and Left Hepatic Arteries.

Question 17

Describe the Venous Drainage of the stomach.

Answer 17

Primary Veins (Most tributaries will drain into these)

• Portal Vein
• Splenic Vein
• Superior Mesenteric Vein
• Inferior Mesenteric Vein

Note: Superior Mesenteric Vein merges with Splenic Vein to give Portal Vein

MOST VEINS RUN ALONGSIDE THEIR ARTERY COUNTERPARTS AND SHARE THEIR NAME.

Question 18

What is the function of the Portal Vein?

Answer 18

Responsible for bringing 70-75% of the nutrient rich/oxygen-poor blood to the Liver. (Hepatic Artery provides the rest)

Question 19

Describe the innervation of the stomach.

Answer 19

Sympathetic fibers from T6-T9 (Greater Splanchnic Nerves) + Afferent (Pain) arterial branches

Parasympathetic supply from CN X

Question 20

Describe the lymphatic drainage of the stomach.

Answer 20

Right side of the stomach drains into the Right Gastric Nodes (via right and left gastric arteries)

Upper quadrant of left side drains into the Pancreaticosplenic Nodes (via short gastric arteries)

Remaining quadrant of left side drains into R&L Gastro-omental nodes, which then drain into Pyloric Nodes.

Question 21

Where in the duodenum does the Foregut end and the Midgut begin?

Answer 21

Segment 2.

Question 22

What is Superior Mesenteric Syndrome?

Answer 22

A growth or aneurysm of the SMA may cause it to occlude the 3rd segment of the duodenum. This can result in projectile vomiting.

Question 23

Which parts of the Small Intestine are retroperitoneal/intraperitoneal?

Answer 23

Retroperitoneal
- Dudoenum (mostly)

Intraperitoneal

• Jejunem
• Ileum

Question 24

What is the blood supply for the Jejunem and Ileum?

Answer 24

Via the unnamed branches of the SMA (Jejunal/Ileal arteries)

Question 25

Describe the lymphatics of the Small Intestine.

Answer 25

Duodenum (above bile duct): drain into Celiac Nodes Rest of Duodenum and Small Intestine: drain into Superior Mesenteric Nodes

Question 26

What are the hallmarks of the Large Intestine?

Answer 26

1. Caliber 2. Omental/Epiploic Appendages 3. Haustrations 4. Taenia Coli

Question 27

What are the Taenia Coli? List their types and associations.

Answer 27

Strips of muscle that are shorter than the actual Large Intestine, giving the organ its haustrations. Taenia mesocolica/mesenteric: transverse mesocolon Taenia omental/anti-mesenteric: greater omentum Taenia free/libra: no association!

Question 28

What do arcades give rise to?

Answer 28

Vasa Rectae

Question 29

How large are the vasa rectae on the jejunal side? Ileal side? How do the arcades look on both sides?

Answer 29

Vasa rectae are larger on the Jejunal side, and the arcades are shorter. (Jews are cheap and big noses!) Vasa rectae are smaller on the Ileal side, and the arcades are longer.

Question 30

What vessel provides the venous drainage for the foregut, midgut, and hindgut?

Answer 30

Foregut: Hepatic Portal Vein Midgut: SMV Hindgut: IMV

Question 31

What are the Porto-Caval anastamoses?

Answer 31

``` Esophageal veins (portal) - Azygos system and tributaries (caval) - Esophageal varices ``` ``` Paraumbilical Veins (portal) - Superficial Abdominal Veins (Caval) - Caput Medusae ``` Superior rectal vein (portal) - Middle and Inferior rectal veins (caval) - Internal Hemorrhoids

Question 32

What is Peptic Ulcer Disease caused by?

Answer 32

Heliobacter pylori (H. pylori)

Question 33

What is another name for GERD (Gastroesophageal Reflux Disease)?

Answer 33

Acid reflux disease (Pyrosis) Chronic symptom of mucosal damage by frequent regurgitation of stomach acid into esophagus. REMEMBER SLIDING HERNIAS?

Question 34

What is Congenital Hypertrophic Pyloric Stenosis?

Answer 34

hypertrophy of pylorus; results in gastric obstruction and projectile vomiting. Affects males over females 5:1

Question 35

Compare SMA Syndrome (Cast/Wilkie's Syndrome) with Nut Cracker Syndrome.

Answer 35

SMA Syndrome: SMA and AA compress 3rd segment of duodenum. Projectile vomiting. Nut cracker Syndrome: Compression of Left Renal Artery between SMA and AA. Results in Left Varicocele.

Question 36

What is Meckel's Diverticulum? What 'Rule' is applied for symptoms?

Answer 36

Yolk sac remnant extends into the umbilical cord. Mimics appendicitis. ``` Rule of 2's: - 2 feet away from ileocolic junction - 2 inches long and 2 cm wide - M>F 2:1 - Children>Adults, younger than 2 - 2% are symptomatic etc. ```