physiology 3 -Pancreatic secretions Carbohydrate absorption Vitamin/mineral absorption Peyer patches Bile

Question 1

A patient with decreased α-amylase may have impaired digestion of what type of food material?

Answer 1

Starch

Question 2

Proteases help digest protein. Name the major proteases secreted by the pancreas.

Answer 2

Trypsin, chymotrypsin, elastase, and carboxypeptidase

Question 3

Are proteases secreted in active or inactive forms?

Answer 3

Inactive forms (called proenzymes or zymogens)

Question 4

After being converted to its active form in the intestinal lumen, trypsin then does what?

Answer 4

It activates the other proenzymes as well as more trypsin molecules

Question 5

For the pancreas, low flow of secretions results in high levels of ____, whereas high flow of secretions results in high levels of ____.

Answer 5

Cl-; HCO3-

Question 6

Are pancreatic secretions hypotonic, isotonic, or hypertonic?

Answer 6

Isotonic

Question 7

A man eats a large amount of popcorn at a movie. What critical enzyme is released in its active form to digest this?

Answer 7

α-amylase

Question 8

Which of these sugars is/are not absorbed by enterocytes: glucose, galactose, fructose, sucrose?

Answer 8

Sucrose, a disaccharide (only monosaccharides are absorbed by enterocytes)

Question 9

Glucose and galactose are taken up by this transporter, which is dependent on this ion.

Answer 9

Sodium-glucose linked transporter (SGTP1); sodium ion

Question 10

____ is the transporter that takes up fructose in enterocytes via what method.

Answer 10

Glucose transporter 5 (GLUT-5); facilitated diffusion

Question 11

All monosaccharides are transported from the enterocytes to the blood by what transporter?

Answer 11

Glucose transporter 2 (GLUT-2)

Question 12

A patient with carbohydrate malabsorption might undergo which test to distinguish GI mucosal damage from other causes of malabsorption?

Answer 12

D-xylose absorption test

Question 13

Iron is absorbed as this ionized form mainly in this part of the small intestine.

Answer 13

Fe2+ is absorbed in the duodenum

Question 14

Folate is mainly absorbed in these parts of the small intestine.

Answer 14

Jejunum and ileum

Question 15

A patient has resection of the ileum as part of surgery for Crohn disease. For which vitamin deficiency might he be at risk?

Answer 15

Vitamin B12 (absorbed in the ileum while bound to intrinsic factor)

Question 16

A patient has severe Crohn disease requiring an extensive colectomy. Which vitamins/minerals is he at risk for deficiency?

Answer 16

Iron, Folate, and vitamin B12 are absorbed in the small bowel (think Iron Fist, Bro)

Question 17

Peyer patches are made of which type of tissue: mucosal, lymphoid, or muscularis?

Answer 17

Lymphoid (Peyer patches are made of unencapsulated lymphoid tissue)

Question 18

In what two layers of the gastrointestinal tract are Peyer patches found?

Answer 18

The lamina propria and the submucosa

Question 19

What is the main action of M cells?

Answer 19

M cells take up antigens from the gut lumen for presentation to B cells and eventual creation of immunoglobulin A (IgA) antibodies

Question 20

After stimulated B cells from Peyer patches have differentiated into plasma cells, what do they then secrete?

Answer 20

Immunoglobulin A, or IgA (Intragut Antibody)

Question 21

After being secreted, immunoglobulin A (IgA) functions to bind what?

Answer 21

Intraluminal antigens (think IgA, the Intragut Antibody)

Question 22

What must IgA receive before it can be transported through the epithelium and into the gut to deal with antigens?

Answer 22

Protective secretory component

Question 23

What are the six components of bile?

Answer 23

Bile salts, phospholipids, cholesterol, bilirubin, water, and ions

Question 24

What is the only means of cholesterol excretion from the body?

Answer 24

Via bile

Question 25

Bile acid conjugation makes bile _____ (more/less) soluble by biding to which two amino acids?

Answer 25

More, glycine and taurine

Question 26

In a patient who is unable to produce bile, what physiologic functions would be impaired?

Answer 26

Excretion of cholesterol, digestion and uptake of lipids and fat-soluble vitamins, & antimicrobial activity

Question 27

A patient has defective cholesterol 7&945;-hydroxylase activity. Does this affect his ability to absorb vitamins in any way?

Answer 27

Yes, as this impairs the rate-limiting step of bile synthesis (one of bile's functions is to assist with vitamin digestion and absorption)

Question 28

In an experiment, bacteria within a Petri dish exposed to gallbladder secretions are noted to perish quickly. What is going on?

Answer 28

Bile has antimicrobial activity via bacterial membrane disruption

Question 29

A patient with hemolytic anemia would be likely to have which abnormal result on liver function tests?

Answer 29

Unconjugated hyperbilirubinemia (bilirubin is a breakdown product of heme)

Question 30

What is the essential structural difference between direct and indirect bilirubin?

Answer 30

Direct bilirubin is conjugated with glucuronic acid and is thus water soluble, whereas indirect bilirubin is not and is thus water insoluble

Question 31

How is bilirubin excreted from the body?

Answer 31

Bilirubin is excreted in bile (it is excreted in urine as urobilin and stool as stercobilin)

Question 32

What type of bilirubin is water soluble: direct or indirect? What type is water insoluble?

Answer 32

Direct bilirubin is water soluble; indirect bilirubin is water insoluble

Question 33

Unconjugated bilirubin travels through the circulation bound to ____. This complex can be measured as ____.

Answer 33

Albumin; indirect bilirubin

Question 34

A patient with impaired bile acid conjugation would develop which abnormality on liver function tests?

Answer 34

Conjugated (direct) hyperbilirubinemia

Question 35

____ is excreted renally, giving ____ its classic yellow color.

Answer 35

Urobilin; urine

Question 36

If exposed to conjugated bilirubin, colonic bacteria will produce what?

Answer 36

Urobilinogen

Question 37

A patient taking antibiotics wipes out his gut flora. His urine is noted to be paler than usual. Why is this the case?

Answer 37

Bilirubin conversion into urobilinogen is impaired; reabsorbed urobilinogen is converted into urobilin, giving urine its yellow color

Question 38

Of the urobilinogen that goes to the kidneys and liver, about ____% is excreted renally and ____% enters the enterohepatic circulation.

Answer 38

10; 90

Question 39

A patient with an obstruction in stercobilin deposition has feces of what characteristic color?

Answer 39

Pale stools (obstruction inhibits its ability to be deposited in the gastrointestinal lumen, leading to pale stools)

Question 40

Urobilinogen cannot be excreted in urine. What form is it excreted in feces, and in a normal patient, what color is the stool?

Answer 40

Excreted in feces as stercobilin, which causes the brown color of stool

Question 41

In an experiment, tagged urobilinogen in the gut can be expected to be later found in which organ?

Answer 41

Liver, via enterohepatic circulation

Question 42

Which enzyme catalyzes bilirubin conjugation?

Answer 42

UDP-glucuronosyltransferase