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Gastro > Liver Physiology (Johnson/Costanzo) > Flashcards

Liver Physiology (Johnson/Costanzo) Flashcards

1
Q

What causes ascites with liver failure?

A

liver responsible for protein synthesis; in failure, decr oncotic pressure = ascites

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2
Q

Cholesterol is used the synthesize:

A

bile acid

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3
Q

Secretin stimulates:

A

secretion of bicarb and water into the ducts

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4
Q

In gallbladder, bile concentrated via:

A

active absorption of Na, Cl, bicarb, water

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5
Q

What are the functions of CCK? What do these cause?

A

contraction of the gallbladder
relaxation of the sphincter of Oddi

**causes stored bile to flow from the gallbladder into the lumen of the duodenum

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6
Q

How does the timing of GB contractions relate to duodenal contractions?

A

they coincide

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7
Q

The hepatocytes of the liver (intermittently/continuously) synthesize and secrete the constituents of bile.

A

continuously

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8
Q

The components of bile are:

A

the bile salts, cholesterol, phospholipids, bile pigments, ions, and water.

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9
Q

What is the function of the GB?

A
  1. store bile
  2. concentrate bile salts (by absorption of water and ions)
  3. eject bile (~30min after meal)
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10
Q

What signals the secretion of CCK?

A

chyme reaching the small intestine

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11
Q

In the small intestine, the bile salts function in:

A

emulsifying and solubilizing dietary lipids

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12
Q

What happens to bile salts once they’ve done their business?

A

When lipid absorption is complete, bile salts are recirculated to liver via enterohepatic circulation
(where they are actively extracted from portal blood)

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13
Q

How are bile acids reabsorbed?

A

40% of bile acids/salts are reabsorbed via passive diffusion

55% of bile acid/salts are actively reabsorbed in the ilium (contains specific receptors for bile acids/salts, Na dependent process)

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14
Q

Decreased reabsorption of bile acids results in:

A

increased bile acid synthesis

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15
Q

Bile acids returning from circulation inhibit:

A

bile acid synthesis via 7-beta-hydroxylase inh
(negative feedback)

**The liver must replace only the small percentage of the bile salt pool that is excreted in feces

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16
Q

Two primary bile acids (synthesized by liver):

What happens to primary bile acids once secreted into lumen of intestines?

A

Cholic acid
Chenodeoxycholic acid

portion of each is dehydroxylated by intestinal bacteria to produce 2 secondary bile acids

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17
Q

4 Bile acids, in order of greatest relative amount to least:

A

Cholic acid > chenodeoxycholic acid > deoxycholic acid > lithocholic acid

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18
Q

How does conjugation of bile acids in the liver change them?

A

conjugation to amino acids changes the pKas of bile acids and causes them to become much more water soluble

**there’s an additional explanation of this in the text that’s good

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19
Q

A “bile salt” is a…

A

bile acid conjugated with an amino acid

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20
Q

The most likely bile acid to be reabsorbed is the one that is the most _____

A

lipophilic

21
Q

The critical property of bile salts is that they are ____.

Why is this significant?

A

amphipathic

allows them to form micelles and forms lipid droplets that repel, which increases surface area for digestion

22
Q

A change in the critical micellar concentration leads to:

A

precipitation of gallstone

23
Q

Micelles solubilize:

A

the products of fat digestion

fat soluble vitamins (which is why decr bile acids&raquo_space; vit deficiency)

24
Q

Micelles are comprised of:

A

4 different bile salts
phospholipids
cholesterol

25
Q

Once the substance has been made soluble, what is the physiologic function of micelles?

A

bring fat digestion products close to the gut wall, allowing for absorption

26
Q
  1. Hepatocytes extract bile acids from the:

2. It is then transported into _____ which drain into bile ducts.

A

portal vein

canaliculi

27
Q

How does bile flow related to portal blood flow?

A

countercurrent, which decreases concentration gradient

28
Q

How do bacteria affect the bile acids/salts in the duodenum?

A

deconjugate and dehydroxlate = less water soluble, which allows passive absorption to occur along length of gut

29
Q

How are bile acids/salts reabsorbed?

A

passively, along length of gut (45%)
actively in ileum

**5% lost in feces

30
Q

Interruption of enterohepatic system can lead to:

A

bile acid deficiency

31
Q

Mechanism by which bile acids are extracted from portal blood:

A

Specialized Na/BA cotransporter extracts BA from blood, which requires Na/K/ATPase pump

BA then secreted into bile canaliculus via specialed BA carrier

32
Q

Secretion of bile acids osmotically drives secretion of:

A

water+electrolytes into bile

33
Q

Mechanism by which bile acids are extracted from portal blood is regulated by:

A

the presence of BA (NOT nerves or hormones)

34
Q

How is bilirubin produced?

A

During metabolism of RBC (in RES):

  1. Removal of iron
  2. Reduction forms Biliverden (green pigment)
  3. Further reduction to bilirubin (yellow pigment)
35
Q

Upon entering the blood, bilirubin is:

A

bound by plasma albumin and transported to liver

36
Q

Bilirubin actively extracted from…

A

albumin

37
Q

Why is bile yellow?

A

bilirubin glucuronide

liver extracts bilirubin and conjugates it with glucuronic acid to form bilirubin glucuronide, which is secreted into bile

38
Q

Intestinal bacteria converts bilirubin to:

A

urobilinogen

39
Q

urobilinogen can ultimately end up…

3

A

recirculated to the liver

excreted in the urine (gives its color, urobilinogen oxidized in kidney)

oxidized to urobilin and stercobilin, the compounds that give stool its dark color

40
Q

Pale poop is the result of…

A

no bilirubin

41
Q

T/F: During contraction of GB, the micelles break apart.

A

F: Throughout this process, the bile acid/salts, phospholipids, cholesterols remain in micelles.

42
Q

How is normal bile different from bile in patients with cholesterol stones?

A

cholesterol stones: bile supersaturated with cholesterol + not enough bile acids

nml: only 50% saturated

43
Q

Obese patients with cholesterol stones: ____ is increased

Non-obese patients with cholesterol stones: ____ are decreased

A

cholesterol

phospholipids

44
Q

Most gallstones are _____ stones

A

cholesterol

45
Q

Pigment stones consist primarily of _____

These stones will precipitate out with ______.

A

bilirubin

calcium

46
Q

What cause pigment stones? What does this damage?

A

bacteria containing beta glucuronidase (deconjugates bilirubin)

GB wall damaged by bacteria

47
Q

How bile acid secretion change following a cholecystectomy?

A

decreased secretion following meal

48
Q

How does hepatic bile secretion change (following a meal) if enterohepatic circulation interrupted?

A

Bile acids present are only those being synthesized

incr in volume and bicarb due to secretin

Gastro (25 decks)

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