GI Basics

Question 1

What “chemicals” assist in the chemical breakdown of food?

Answer 1

Hydrochloric acid and pepsin

Question 2

Hydrochloric acid is secreted by _____.

Answer 2

parietal cells

Question 3

What are the functions of hydrochloric acid?

Answer 3

1. solvent that dissolves food
2. activates pepsin (to begin protein digestion)
3. stimulates duodenal release of other digestive enzymes
4. kills bacteria in food

Question 4

What is the function of pepsin?

Answer 4

digests proteins

Question 5

Pepsinogen is secreted by ____.

Answer 5

chief cells

Question 6

Which 3 hormones stimulate the parietal cells to secrete hydrochloric acid?

Answer 6

1. gastrin
2. histamine
3. acetylcholine

Question 7

What is the function of gastrin?

Answer 7

stimulate stomach acid secretion and motility

Question 8

____ cells secrete gastrin which causes _____ cells to secrete ________.

Answer 8

1. G cells
2. Enterochromaffin-like cells
3. histamine

Question 9

What is the function of histamine?

Answer 9

stimulate the parietal cells to secrete HCl in response to gastrin

Question 10

What is the function of acetylcholine?

Answer 10

directly stimulate the parietal cells to secrete HCl

Parasympathetic system (primarily vagus nerve!)

Question 11

What is the function of somatostatin?

Answer 11

act as negative feedback mechanism to inhibit secretion of gastrin, insulin, glucagon, pancreatic enzymes, and gallbladder contraction

Question 12

Somatostatin is produced by _____ cells.

Answer 12

Delta (D cells)

Question 13

What are the main functions of the large intestine?

Answer 13

1. Absorb remaining water from undigested food
2. Transport undigested food for removal via feces– contains Haustra
3. Absorb certain vitamins produced by bacteria (vit. K, biotin)

Question 14

The large intestine consists of the _____ and the _____.

Answer 14

cecum and colon

Question 15

What is the function of the duodenum?

Answer 15

responsible for most of the chemical digestion of small intestine and regulates the rate of stomach emptying

Question 16

Secretin is released by the _____.

Answer 16

Duodenum

Question 17

What is the function of secretin?

Answer 17

causes the pancreas to release bicarbonate to buffer the acid from the chyme entering the duodenum from the stomach

Question 18

What are the functions of cholecystokinin (CCK)?

Answer 18

1. stimulate release of pancreatic enzymes (trypsin, amylase, lipase)
2. increase bicarb release
3. stimulate gall bladder contraction and bile release

Question 19

What is the function of bile release?

Answer 19

help to emulsify fats to make lipase breakdown of fats more effective

Question 20

Which substances are produced by the acinar cells of the pancreas?

Answer 20

1. bicarb
2. proteases
3. amylase
4. lipase

Question 21

The exocrine gland of the pancreas contains the _____ cells.

Answer 21

acinar

Question 22

The function of proteases (trypsinogen, chymotrypsinogen)

Answer 22

precursors to enzymes that break down proteins. Are released in an inactive form to prevent auto digestion

Question 23

Function of amylase?

Answer 23

breaks down starches into simple sugars

Question 24

Function of lipase?

Answer 24

breaks down fats into fatty acids (with help of bile salts which increase surface area)

Question 25

The endocrine gland of the pancreas contains the _____.

Answer 25

islets of Langerhans

Question 26

Insulin is produced by _____ cells and its function is _____

Answer 26

beta cells | decrease blood glucose levels

Question 27

Glucagon is produced by _____ cells and its function is _____

Answer 27

alpha cells | increase blood glucose levels

Question 28

What substances are produced by the islets of Langerhans of the pancreas?

Answer 28

1. insulin 2. glucagon 3. somatostatin

Question 29

Upper endoscopy is the diagnostic test of choice for what conditions?

Answer 29

1. Mallory-Weiss tear | 2. PUD

Question 30

Barium enema is contraindicated if what is suspected?

Answer 30

Perforation! it is an irritant outside of the structures of the GI tract Also in acute ulcerative colitis (can cause toxic mega colon)

Question 31

An esophageal manometry (esophageal motility study) is the diagnostic test of choice for what conditions?

Answer 31

1. achalasia | 2. nutcracker esophagus

Question 32

What is the function of the diagnostic test ERCP?

Answer 32

Is an upper GI endoscopy + X-rays to diagnose and treat disorders of the bile or pancreatic ducts

Question 33

What is the function of the diagnostic test esophageal manometry?

Answer 33

used to monitor pressure changes especially of the lower and upper esophageal sphincter. Used for motility disorders, evaluate peristalsis and patients with difficulty swallowing

Question 34

What are the 3 phases of bilirubin metabolism?

Answer 34

1. Prehepatic phase 2. Intrahepatic phase 3. Post hepatic phase

Question 35

Bilirubin is produced from ______.

Answer 35

heme metabolism

Question 36

What happens in the pre hepatic phase of bilirubin metabolism?

Answer 36

Heme is degraded esp. in liver and spleen by macrophages. Heme ---> biliverdin (green) ---> unconjugated bilirubin (red-orange) ---> sent to liver for conjugation and excretion

Question 37

______ bilirubin is NOT soluble in water.

Answer 37

Unconjugated (indirect)

Question 38

Unconjugated bilirubin is conjugated via the enzyme _____.

Answer 38

glucuronosyltransferase (UGT)

Question 39

What happens during the intrahepatic phase of bilirubin metabolism?

Answer 39

In hepatocytes, the unconjugated bilirubin is conjugated via UGT enzyme

Question 40

______ bilirubin IS soluble in aqueous bile

Answer 40

Conjugated

Question 41

What happens during the post hepatic phase of bilirubin metabolism?

Answer 41

Bilirubin is transported thru biliary and cystic ducts to be stored in gallbladder to enter the intestine ---> then conjugated bilirubin converted to urobilinogen that can go thru 3 pathways

Question 42

When conjugated bilirubin reaches the intestine it is then converted to ______.

Answer 42

urobilinogen

Question 43

What are the 3 main pathways urobilinogen can go thru?

Answer 43

1. is oxidized by intestinal bacteria to stercobilin (gives stool its brown color) 2. is converted in kidney to urobilin and excreted (gives urine its color) 3. is recycled back to the liver and bile for reuse

Question 44

What gives stool its brown color?

Answer 44

stercobilin

Question 45

What gives urine its color?

Answer 45

urobilin

Question 46

Jaundice occurs when bilirubin levels are ______ mg/dL.

Answer 46

> 2.5

Question 47

What etiologies can cause jaundice?

Answer 47

1. increased bilirubin production (hemolysis) 2. decreased bilirubin uptake 3. impaired conjugation 4. biliary obstruction 5. hepatitis

Question 48

If a pt has increased bilirubin without increased LFTs you should suspect --->

Answer 48

familial bilirubin discorders (Gilbert's, Dubin-Johnsons) and hemolysis