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SF4 Exam I > Bile and Large Intestine > Flashcards

Bile and Large Intestine Flashcards

1
Q

bile is required for what?

A

digestion and absorption of many fats and fat soluble vitamins and for excretion of water-insoluble substances such as cholesterol and bilirubin

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2
Q

bile is produced by what and when?

A

hepatocytes

produced continuously

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3
Q

bile is stored where and when

A

gallbladder

during interdigestive period

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4
Q

bile composition (name whats in it)

A 
bile acids
phospholipids
cholesterol
bile pigments
electrolytes
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5
Q

primary bile acids are synthesized where and from what

A

liver

from cholesterol

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6
Q

in the intestine primary bile acids are converted to what by what

A

secondary bile acids

bacteria in intestine

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7
Q

in the liver what happens to bile acids

A

the are conjugated to glycine or taurine

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8
Q

bile acids are conjugated to what?

A

glycine or taurine

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9
Q

bile salt (what is it)

A

conjugated bile acid (with either glycine or taurine) with Na+ ions

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10
Q

bile acids are conjugated why?

A

more water soluble at intestinal pH

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11
Q

bile acids are what at physiologic pH (ionized or neutral) and what does this do

A

ionized and thus cannot be passively absorbed

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12
Q

in aqueous solutions what do bile salts do to lipids?

A

orient around droplets of lipid and keep lipid dispersed in emulsion

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13
Q

bile salts are polar, non polar, or amphipathic?

A

amphipathic

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14
Q

when on the outside of a cylindrical micelle where is the hydrophilic portion of the bile salt?

A

oriented towards aqueous solution of intestinal lumen

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15
Q

what is on the inside of a micelle formed by bile salts?

A

free fatty acids, monoglycerides, fat-soluble vitamins, and cholesterol

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16
Q

primary bile salts include (name a few)

A

cholates

chenodeoxycholates

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17
Q

secondary bile salts include

A

deoxycholates
ursodeoxycholates
lithocholates

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18
Q

what type of phospholipid primarily makes up bile is?

A

lecithins

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19
Q

phospholipids are normally insoluble in water, how are they solubilized?

A

bile salt micelles

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20
Q

micelles are able to more effectively soluble lipids when they contain what?

A

phospholipids

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21
Q

before cholesterol can be secreted in bile what must occur?

A

solubilized by bile salt micelles

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22
Q

what is the primary excretory pathway for cholesterol and how?

A

bile

via loss of bile salts in feces

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23
Q

what happens if more cholesterol is present than can be solubilized

A

crystals form in bile (can serve as seed for gallstone formation)

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24
Q

what is the principle bile pigment and where does it come from

A

bilirubin (metabolite of hemoglobin)

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25
Q

bilirubin is insoluble in water, how is it made soluble

A

when conjugated to glucuronic acid in liver

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26
Q

bilirubin is or is not present in micelles

A

not present

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27
Q

obstruction of bile duct or damage to liver cells (a well as obliteration of RBCs) can cause what?

A

jaundice

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28
Q

jaundice (what is it and what is it due to)

A

yellowish tint of body tissues

due to large quantities of bilirubin in plasma

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29
Q

what electrolytes are found in bile

A

Na+
Cl-
HCO3-

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30
Q

the total bile pool must circulate at least how many times per meal?

A

twice

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31
Q

most bile salts that enter small intestine are actively reabsorbed where and what type of transport mechanism (passive or active)

A

terminal ileum

active transport mechanism

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32
Q

deconjugated bile acids are absorbed by what type of transport mechanism?

A

passive diffusion

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33
Q

osmotic filtration (what is it)

A

process by which water and electrolytes enter the bile through paracellular pathway along an osmotic gradient

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34
Q

hepatocytes extract bile and Na+ from where and how?

A

portal blood

via secondary active transport

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35
Q

how do hepatocytes secrete bile acids (what type of pump)?

A

ATPase-dependent bile acid export pump

36
Q

what happens to bile salts not reabsorbed in the small intestine

A

excreted in feces

37
Q

what determines the rate of bile salt synthesis

A

rate of return to liver

38
Q

bile-independent fraction of biliary secretion (what does it mean and what stimulates it)

A

refers to volume of secretion of water and electrolytes

secretin stimulates secretion of HCO3- and water

39
Q

bile-dependent fraction of biliary secretion

what is it

A

refers to quantity of bile salts secreted by liver

40
Q

amount of bile salts secreted by the liver is directly related to what?

A

amount of bile salts absorbed by the liver

41
Q

bile salts and acids are potent stimulaters of what?

A

bile secretion

bile-dependent fraction of biliary secretion

42
Q

bile salts and acids are inhibitors of what?

A

new bile acid synthesis

43
Q

increased bile acid secretion has what effect on bile acid return to the liver and bile acid synthesis of liver

A

increases bile return to liver

inhibits bile acid synthesis

44
Q

decreased bile acid secretion has what effect on bile acid return to the liver and bile acid synthesis of liver

A

decreased bile acid return to liver

stimulates bile acid synthesis

45
Q

the gallbladder collects what type of bile

A

that which is secreted from the liver during interdigestive periods

46
Q

the gallbladder does what to the bile it collects?

A

concentrates it

47
Q

how does the gallbladder concentrate bile

A

actively removes Na+, Cl- and HCO3-

water removed by osmotic gradient

48
Q

what stimulates contraction of gallbladder (major stimulus as well as non major)

A 
CCK (major stimulus)
vagal activity (also stimulus)
49
Q

CCK is released in response to what?

A

fatty acids and small peptides in duodenum

50
Q

two action of CCK are (in relation to gallbladder)

A

contracts smooth muscle of gallbladder

relaxes sphincter of Oddi

51
Q

cholelithiasis is another term for what?

A

gallstones

52
Q

gallstones (what are the two types)

A

cholesterol

pigment

53
Q

about 80% of gallstones in Western societies are what type?

A

cholesterol

54
Q

how are cholesterol gallstones formed?

A

when proportions of phospholipids, cholesterol, and bile salts is altered, cholesterol crystalizes due to supersaturation
crystals act as nucleus for stone formation

55
Q

pigment gallstones (how are they formed and what do they consist of?)

A

bilirubin becomes unconjugated, which is insoluble in bile

the insoluble bilirubin precipitates with Ca2+ to begin stone-forming process

56
Q

calcium bilirubinate (what is it)

A

what makes up a pigment stone

57
Q

how are gallstones treated?

A

surgical removal of gallbladder (cholecystectomy)

58
Q

after a cholecystectomy what happens to bile?

A

empties slowly but continuously into duodenum

59
Q

after a cholecystectomy what happens to digestion?

A

normal digestion and absorption unaffected
fats can still be digested
high-fat foods should be avoided

60
Q

the large intestine absorbs what?

A

some electrolytes

most fluids passed into it from small intestine

61
Q

Haustra (Haustrations)

what are they

A

sac-like segments in colon; locations not fixed
present when colon empty
disappear during, and reappear following, contractions of specific segment

62
Q

when is the ileocecal sphincter relaxed and what does this do?

A

when ileum is distended

contents of small intestine flow into colon

63
Q

when is the ileocecal sphincter contracted and what does this do?

A

when colon distended

prevents reflux into ileum

64
Q

majority of movements in proximal colon are what type of contractions

A

segmentation contractions

65
Q

segmentation contractions of the large intestine do what

A

partially responsible for appearance of houstra

serve to mix contents, exposing them to absorptive surfaces

66
Q

peristaltic contractions of the large intestine are responsible for what?

A

move chyme slowly along colon (5cm/hr)

can take up to 48 hours for chyme to transverse colon

67
Q

residual of meal can still be in rectum for how long after a meal

A

72 hours

68
Q

mass movement in large intestine (what is it, how often does it occur, what does it do)

A

peristaltic wave
occurs 1-3 times/day
moves colonic contents long distances

69
Q

what propels material into rectum from distal colon

A

mass movements

70
Q

in the distal colon what is the consistency and speed of fecal matter

A

semi-solid material

moves slowly b/c most water absorption occurs in proximal colon

71
Q

what type of contractions are most prominent in the distal colon

A

segmentation

72
Q

the rectum is usually how full of material

A

empty (or nearly so)

73
Q

what is the frequency of segmental contractions in the rectum compared to sigmoid colon and what effect does this have

A

contraction more frequent in rectum

causes retrograde movement of fecal material into sigmoid colon

74
Q

rectosphincteric reflex (what is it)

A

when fecal material forced into rectum, rectum contracts and internal anal sphincter relaxes

75
Q

when is the urge to defecate produced?

A

when rectum filled to 25% of capacity

76
Q

what prevents defecation?

A

external anal sphincter (normally tonically contracted)

77
Q

individuals lacking tonic contraction of external anal sphincter?

A

will defecate anytime the rectum fills with fecal mater from the retrosphincteric reflex

78
Q

how does the urge to defecate subside?

A

if defecation does no occur, internal anal sphincter contracts and rectum relaxes to accommodate fecal material within in

79
Q

feces (contents)

A

inorganic material, undigested plant fibers, bacteria, and water

80
Q

what kind of affect do variations in diet have on composition of feces

A

relatively little

81
Q

large fraction of fecal mass is from where in origin

A

no dietary

82
Q

in a starving individual defecation does or does not occur

A

does

83
Q

Hirschsprung’s Disease (congenital megacolon)

A

caused by absence of enteric nervous system from segment of colon
interruption of enteric nervous system results in tonic contraction
material accumulates proximal to contraction, dilating the colon
severe constipation

84
Q

surgical removal of aganglionic segment is treatment for what?

A

Hirschsprung’s Disease (congenital megacolon)

85
Q

constipation (what is it)

A

increased time of passage or transit of material through colon

86
Q

constipation involves what two changes?

A

increased storage capacity of cecum and ascending and transverse parts of colon
decreased propulsive capacity of descending and sigmoid colon

87
Q

what diminishes frequency of bowel movements?

A 
ignoring urge to defecate
lack of exercise
some medications (narcotics, antidepressants)
old age
long-term use of laxatives

SF4 Exam I (16 decks)

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