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

1
Q

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

A

Starch

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2
Q

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

A

Trypsin, chymotrypsin, elastase, and carboxypeptidase

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3
Q

Are proteases secreted in active or inactive forms?

A

Inactive forms (called proenzymes or zymogens)

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4
Q

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

A

It activates the other proenzymes as well as more trypsin molecules

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5
Q

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

A

Cl-; HCO3-

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6
Q

Are pancreatic secretions hypotonic, isotonic, or hypertonic?

A

Isotonic

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7
Q

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

A

α-amylase

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8
Q

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

A

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

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9
Q

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

A

Sodium-glucose linked transporter (SGTP1); sodium ion

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10
Q

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

A

Glucose transporter 5 (GLUT-5); facilitated diffusion

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11
Q

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

A

Glucose transporter 2 (GLUT-2)

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12
Q

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

A

D-xylose absorption test

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13
Q

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

A

Fe2+ is absorbed in the duodenum

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14
Q

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

A

Jejunum and ileum

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15
Q

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

A

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

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16
Q

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

A

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

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17
Q

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

A

Lymphoid (Peyer patches are made of unencapsulated lymphoid tissue)

18
Q

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

A

The lamina propria and the submucosa

19
Q

What is the main action of M cells?

A

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

20
Q

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

A

Immunoglobulin A, or IgA (Intragut Antibody)

21
Q

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

A

Intraluminal antigens (think IgA, the Intragut Antibody)

22
Q

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

A

Protective secretory component

23
Q

What are the six components of bile?

A

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

24
Q

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

A

Via bile

25
Q

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

A

More, glycine and taurine

26
Q

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

A

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

27
Q

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

A

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

28
Q

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

A

Bile has antimicrobial activity via bacterial membrane disruption

29
Q

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

A

Unconjugated hyperbilirubinemia (bilirubin is a breakdown product of heme)

30
Q

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

A

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

31
Q

How is bilirubin excreted from the body?

A

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

32
Q

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

A

Direct bilirubin is water soluble; indirect bilirubin is water insoluble

33
Q

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

A

Albumin; indirect bilirubin

34
Q

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

A

Conjugated (direct) hyperbilirubinemia

35
Q

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

A

Urobilin; urine

36
Q

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

A

Urobilinogen

37
Q

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

A

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

38
Q

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

A

10; 90

39
Q

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

A

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

40
Q

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

A

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

41
Q

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

A

Liver, via enterohepatic circulation

42
Q

Which enzyme catalyzes bilirubin conjugation?

A

UDP-glucuronosyltransferase