Organ Systems II GI Anat Phys Embr Part I (RC)

Question 1

What 2 things are needed for the LES to function properly?

Answer 1

1) Inner circular esophageal muscle layer 2) Loop of diaphragm around esophagus

Question 2

Why does the LES not work well when there is a Hiatal Hernia?

Answer 2

Because part of its function depends upon the diaphragm circling around it

Question 3

What vein drains the foregut, midgut and hindgut?

Answer 3

The portal vein

Question 4

Cirrhosis causes portal hypertension, what is the significance of this condition?

Answer 4

Blood can’t get through the liver effectively, so it shunts it through the Azygous and Hemiazygous veins in order to get it back to the heart. Blood also backs up into other structures like the esophageal veins, this causes esophageal varices.

Question 5

The Vagus nerve has been surgically cut (ligated) in the past before it’s function was fully understood. Why did we do this?

Answer 5

The Vagus nerve releases Ach in the stomach, and the stomach in turn produces HCl. If someone had ulcers that could not be treated in any other way, the nerve would be cut… stopping the release of Ach and thus stopping acid production.

Question 6

Why do esophageal cancers metastasize so quickly?

Answer 6

No serosa

Question 7

What cell type normally lines the esophagus?

Answer 7

Stratified Squamous epithelium

Question 8

Why are most esophageal cancers NOT squamous cell carcinoma?

Answer 8

Intestinal metaplasia occurring in invading columnar epithelium from the stomach causes Barrett’s esophagus and thus adenocarcinoma.

Question 9

How can having a hiatial hernia ultimately lead to cancer?

Answer 9

Acid reflux leads to intestinal metaplasia (influx of columnar epithelium from the stomach)

Question 10

What are the tissue layers of the GI tract? Name them from inner to outer.

Answer 10

From inner to outer:

Mucosa (stratified squamous epithelium, lamina propria, muscularis mucosa)

Submucosa

Circular muscle

Longitudinal muscle

Serosa or adventitia (except esophagus)

Question 11

What structure causes the plica circulares to form?

Answer 11

Muscularis mucosa

Question 12

What layer of GI tissue houses the glands?

Answer 12

Submucosa

Question 13

What is the blood supply to the foregut?

Answer 13

Celiac a.

Question 14

What is the blood supply to the midgut?

Answer 14

Superior mesenteric a.

Question 15

What is the blood supply to the hindgut?

Answer 15

Inferior mesenteric a.

Question 16

What defines the boundaries of the gut?

Answer 16

The blood supply

Question 17

Which Vagus nerve can be seen on the anterior surface of the stomach?

Answer 17

Clockwise rotation makes the left branch of the Vagus anterior

Question 18

Which divisions of the gut have both dorsal and ventral mesogastrium?

Answer 18

Note that the foregut is the only place where the structures are tethered both dorsal and ventral by their respective mesogastrium

Question 19

Why is the greater omentum important?

Answer 19

Walls off inflammatory processes in the abdomen

Question 20

What artery comes off the aorta cephalad (towards the head or anterior) to the pancreas?

Answer 20

Celiac

Question 21

Which artery comes off caudad to the body of the pancreas, but cephalad to the insula?

Answer 21

SMA

Question 22

Why is the antrum of the stomach sometimes removed, and where is it located?

Answer 22

Inferior portion of stomach leading to pyloric valve. Intractable peptic ulcer disease

Question 23

Where is the pylorus and what does it do?

Answer 23

Valve separating the stomach from the duodenum. Regulates the rate of entry of chyme into the sm. intestine

Question 24

Describe the greater and lesser curvatures, the direction the muscle layers travel, and the folds that increase surface area in the stomach.

Answer 24

Question 25

Why does the stomach have 3 muscle layers, not two, like the rest of the GI?

Answer 25

Helps churn food

Question 26

What do flattened rugae indicate?

Answer 26

If the rugae, folds, are flattened, it may indicate stomach inflammation (gastritis)

Question 27

Why do babies with pyloric stenosis have non-bilious vomiting?

Answer 27

Bile is released by the common bile duct in the duodenum, so the bile cannot get backwashed into the stomach as the enlarged pyloris prevents this.

Question 28

What is the classic metabolic disturbance in pyloric stenosis and why?

Answer 28

Blood tests will reveal hypokalemic, hypochloremic metabolic alkalosis from the loss of gasric acid (which contains hydrocholic acid and potassium) via persistent vomiting.

Question 29

If you find an ulcer at location V, what location is this and what is associated with causing it?

Answer 29

Type V are located in the body of the stomach. Type V occur with NSAID use.

Question 30

Type I-IV ulcers are found where? What causes them?

Answer 30

Type I,II inferior to LES. Type II also duodenum. . Type III Superior to pyloris, along lesser curvature. Type IV in fundus. 75% on lesser curvature. Most have normal acid but abnormal mucosal defense. Type A blood associated with Type I ulcers, Type O blood associated with all others.

Question 31

Where is iron absorbed?

Answer 31

In the duodenum

Question 32

Where does the foregut end?

Answer 32

The foregut ends after the first portion of the duodenum, a location when the bile and pancreatic ductsdrain into the duodenum.

Question 33

Why do anterior duodenal ulcers perforate and posterior duodenal ulcers bleed?

Answer 33

The peritoneal or abdominal cavity is located anterior to the duodenum. Therefore, if an anterior ulcer grows deep enough, it will perforate; whereas if a posterior ulcer grows deep enough, it will perforate the gastroduodenal artery and bleed. The largest arterial supply generally comes from the posterior surface of a hollow viscus (intestines and stomach).

Question 34

When does pancreatic cancer occur in most people and what are its symptoms?

Answer 34

In their 50s and 60s. Pain radiating to the spine.

Question 35

Why are pancreatic tumors inoperable?

Answer 35

The tumor has encased the SMA and SMV