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Physiology Test 3 > Bile > Flashcards

Bile Flashcards

1
Q

What is the unstirred water layer?

A
  • As chyme gets near intestinal wall (enterocytes), flow becomes slower
  • Enterocytes also secreting out mucus and bicarb that helps protect cell
    • mucus further slows chyme
  • This creates unstirred water layer
    • most nutrients can get to enterocytes
    • only problem with lipids (because hydrophobic)
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2
Q

Which nutrients aren’t able to go through stirred water layer?

A
  • Lipids- because they’re hydrophobic, can’t get through stirred water layer on own
  • need carrier- bile
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3
Q

How does bile help lipids to get through stirred water layer?

A
  • By forming Micelle (think of taxi)
    • take lipids through unstirred water layer and drop them off to diffuse into enterocyte
  • Bile works with lipid, enzymes to create micelle
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4
Q

Where is bile synthesized?

A

Hepatocytes in Liver

hepatocytes are functional cells of liver

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5
Q

What forms primary bile?

A
  • Cholic acid (main type of parimary bile)
    • made from cholesterol backbone
      • get cholesterol from diet
      • synthesis as well
        • occurs in hepatocytes through enzyme HMG CoA reductase
    • also metabolic waste
    • excess phospholipids
    • bilirubin
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6
Q

How do we make cholesterol in hepatocytes?

A

Through HMG CoA reductase

  • where statin drugs work to lower plasma cholesterol levels
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7
Q

Bile is ____

(how does it interact w/ water

A

amphipathic

because of conjugation

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8
Q

How do we make bile polar (hydrophilic?)

A
  • Conjugation with taurine, glycine
    • this makes it hydrophilic on one side with amino acid
  • Remains hydrophobic on cholesterol end?
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9
Q

Around lipids, bile act as an _____

A

emulsifier

  • acts like dish soap and makes smaller lipid droplets
    • bile does not digest the lipids whatsoever, just acts like dish soap to emulsify lipid
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10
Q

What is secondary bile?

A
  • Primary bile that has been acted on by intestinal bacteria
    • this happens lower in intestinal tract, mainly colon
  • Secondary bile not ampipathic, much more lipophilic
    • hard time with getting through to enterocytes in lower part small intestine
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11
Q

Once bile is made where is it secreted?

A

Bile duct

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12
Q

What happens when bile is secreted into ducts?

A
  • Pulls water and solute with it since bile is highly osmotic
  • When secreting bile, effectively secreting a buffer since NaHCO3 comes with it
    • called solvent drag
  • Important for buffering acidic chyme out of stomach
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13
Q

What nerve is activated when food goes in mouth/stomach?

A

Activation of vagus nerve

  • This increases bile production in liver
  • Allows relaxation at sphincter of oddi so any small amt bile in bile duct can get to duodenum
    • ramps up even more once chyme in duodenum
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14
Q

What happens when chyme released into duodenum?

A
  • Presence of chyme in duodenum releases duodenal hormones
    • Increases CCK into blood
      • circulates and contributes more to bile production
      • relaxes sphincter oddi
      • start rhthmic contraction of gallbladder with stored bile
        • allows bile to spurt into duodenum onto chyme
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15
Q

Where is bile reabsorbed?

A

Terminal ileum

  • Transporters on terminal ilieum allow bile back into enterocyte
  • goes to portal system and recycles back to liver to be resecreted
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16
Q

How long does bile secretion/recycling continues?

A

As long as chyme is coming down tract and CCK secreted into blod

17
Q

How much bile is lost in each cycle of recycling?

A

10%

18
Q

What happens at end of meal?

A
  • Once no more chyme coming down tract, secretion of CCK reduces
  • this blocks spincter of oddi
  • any bile recycled back, stored again in gallbladder for next meal
19
Q

We rid body of cholesterol, bilirubin and waste via ____

A

feces

20
Q

What are gallstones?

A

Accretion of bile

can block bile ducts and lead to emergency sx

21
Q

What does CCK do?

A

Cholecystokinin

  • released into blood once chyme coming down tract
  • Stimulates bile production
  • gall bladder contractions
  • opens sphincter of oddi
  • stimualtes secretion pancreatic enzymes
22
Q

The term “bile acid” or “bile salts” are used ____

A

interchangably

as soon as bile acid comes near sodium, becomes a bile salt

23
Q

What is progression of formation of micelles?

A
  • Fat droplet comes in contact with bile salts, causing imulsion
  • Bile salts+ pancretic lipase with co-lpase forms micelles
24
Q

Micelle does not form until action of _____

A

pancretic lipase and co-lipase

25
Q

Most of lipids come out ____ in meal

A

later

Lipids floating to top of stomach

26
Q

What is role of pancretic lipase in micelle?

A
  • Hydrolyzes lipids
  • BUT CANNOT reach lipids by itself
    • needs co-lipase in order to reach lipid ccovered in bile
27
Q

What is role of co-lipase?

A

Co-lipase allows opening in bile so pancreatic lipase can come in

28
Q

Function of gallbladder?

A

Dehydrates and stores bile

29
Q

What happens if you remove gallbladder?

A
  • Reduce storage of bile
  • liver needs to increase production of bile
  • Complications after successful sx is rare but 5-40% of patients by develop postcholecystectomy synrdome
    • chornic GI distress
    • pain in RUQ
  • Up to 20% develop diarrhead
    • more osmotic effect because more bile secreted from liver
    • more bile in feces, more chance of diarrhea
30
Q

What can be given to reduce diarrhea after cholecystectomy/ileal resection?

A

Cholestyramine

  • Binds to bile and makes less osmotically active
31
Q

Is there still bile recycling with gallblader removal?

A

Yes, but just not as good

32
Q

After gallbladder removal, where does the recycled bile go?

A

Stays in bile duct. Not as effective storage without gallbladder

33
Q

What happens to bile if ileum removes?

A
  • Little to no recycling of bile
  • bile excreted by gallbladder and liver excreted in feces
  • When sphincter of oddi closes, only bile remaining in ducts is “vacuumed” into gallbladder and stored
  • liver produces more bile because it does not sense any bile recycled
  • Pt needs to decrease fat
    • pt will get diarrhea because of increased bile in feces
    • cholestyramine can also be used to help contorl diarrhea
34
Q

What else is importnat about bile?

A

Bilirubin metabolism/excretion

35
Q

Bilirubin secreted with bil is ______ with ___ ___

A

conjugated; glucuronic acid

36
Q

What do colonic bacteria do to bilirubin?

A

Remove acid moiety and bilirubin is converted to urobilinogen

37
Q

WHat happens to urobilinogen in colon?

A
  • 10-20% is absorbed, recycled into portal blood, returned to systemic circulation, where it is filtered and then converted to urobilin (yellow color) and excreted into urine
  • other portion urobilinogen is oxidized by intestinal bacteria to brown stercobilin
    • excreted in feces
    • makes feces brown
38
Q

What makes your feces brown?

A

Stercobilin

39
Q

What is urobilinogen converted to in kidney?

A

Urobilin

Physiology Test 3 (9 decks)

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