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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
bilirubin is insoluble in water, how is it made soluble
when conjugated to glucuronic acid in liver
26
bilirubin is or is not present in micelles
not present
27
obstruction of bile duct or damage to liver cells (a well as obliteration of RBCs) can cause what?
jaundice
28
jaundice (what is it and what is it due to)
yellowish tint of body tissues | due to large quantities of bilirubin in plasma
29
what electrolytes are found in bile
Na+ Cl- HCO3-
30
the total bile pool must circulate at least how many times per meal?
twice
31
most bile salts that enter small intestine are actively reabsorbed where and what type of transport mechanism (passive or active)
terminal ileum | active transport mechanism
32
deconjugated bile acids are absorbed by what type of transport mechanism?
passive diffusion
33
osmotic filtration (what is it)
process by which water and electrolytes enter the bile through paracellular pathway along an osmotic gradient
34
hepatocytes extract bile and Na+ from where and how?
portal blood | via secondary active transport
35
how do hepatocytes secrete bile acids (what type of pump)?
ATPase-dependent bile acid export pump
36
what happens to bile salts not reabsorbed in the small intestine
excreted in feces
37
what determines the rate of bile salt synthesis
rate of return to liver
38
bile-independent fraction of biliary secretion (what does it mean and what stimulates it)
refers to volume of secretion of water and electrolytes | secretin stimulates secretion of HCO3- and water
39
bile-dependent fraction of biliary secretion | what is it
refers to quantity of bile salts secreted by liver
40
amount of bile salts secreted by the liver is directly related to what?
amount of bile salts absorbed by the liver
41
bile salts and acids are potent stimulaters of what?
bile secretion | bile-dependent fraction of biliary secretion
42
bile salts and acids are inhibitors of what?
new bile acid synthesis
43
increased bile acid secretion has what effect on bile acid return to the liver and bile acid synthesis of liver
increases bile return to liver | inhibits bile acid synthesis
44
decreased bile acid secretion has what effect on bile acid return to the liver and bile acid synthesis of liver
decreased bile acid return to liver | stimulates bile acid synthesis
45
the gallbladder collects what type of bile
that which is secreted from the liver during interdigestive periods
46
the gallbladder does what to the bile it collects?
concentrates it
47
how does the gallbladder concentrate bile
actively removes Na+, Cl- and HCO3- | water removed by osmotic gradient
48
what stimulates contraction of gallbladder (major stimulus as well as non major)
``` CCK (major stimulus) vagal activity (also stimulus) ```
49
CCK is released in response to what?
fatty acids and small peptides in duodenum
50
two action of CCK are (in relation to gallbladder)
contracts smooth muscle of gallbladder | relaxes sphincter of Oddi
51
cholelithiasis is another term for what?
gallstones
52
gallstones (what are the two types)
cholesterol | pigment
53
about 80% of gallstones in Western societies are what type?
cholesterol
54
how are cholesterol gallstones formed?
when proportions of phospholipids, cholesterol, and bile salts is altered, cholesterol crystalizes due to supersaturation crystals act as nucleus for stone formation
55
pigment gallstones (how are they formed and what do they consist of?)
bilirubin becomes unconjugated, which is insoluble in bile | the insoluble bilirubin precipitates with Ca2+ to begin stone-forming process
56
calcium bilirubinate (what is it)
what makes up a pigment stone
57
how are gallstones treated?
surgical removal of gallbladder (cholecystectomy)
58
after a cholecystectomy what happens to bile?
empties slowly but continuously into duodenum
59
after a cholecystectomy what happens to digestion?
normal digestion and absorption unaffected fats can still be digested high-fat foods should be avoided
60
the large intestine absorbs what?
some electrolytes | most fluids passed into it from small intestine
61
Haustra (Haustrations) | what are they
sac-like segments in colon; locations not fixed present when colon empty disappear during, and reappear following, contractions of specific segment
62
when is the ileocecal sphincter relaxed and what does this do?
when ileum is distended | contents of small intestine flow into colon
63
when is the ileocecal sphincter contracted and what does this do?
when colon distended | prevents reflux into ileum
64
majority of movements in proximal colon are what type of contractions
segmentation contractions
65
segmentation contractions of the large intestine do what
partially responsible for appearance of houstra | serve to mix contents, exposing them to absorptive surfaces
66
peristaltic contractions of the large intestine are responsible for what?
move chyme slowly along colon (5cm/hr) | can take up to 48 hours for chyme to transverse colon
67
residual of meal can still be in rectum for how long after a meal
72 hours
68
mass movement in large intestine (what is it, how often does it occur, what does it do)
peristaltic wave occurs 1-3 times/day moves colonic contents long distances
69
what propels material into rectum from distal colon
mass movements
70
in the distal colon what is the consistency and speed of fecal matter
semi-solid material | moves slowly b/c most water absorption occurs in proximal colon
71
what type of contractions are most prominent in the distal colon
segmentation
72
the rectum is usually how full of material
empty (or nearly so)
73
what is the frequency of segmental contractions in the rectum compared to sigmoid colon and what effect does this have
contraction more frequent in rectum | causes retrograde movement of fecal material into sigmoid colon
74
rectosphincteric reflex (what is it)
when fecal material forced into rectum, rectum contracts and internal anal sphincter relaxes
75
when is the urge to defecate produced?
when rectum filled to 25% of capacity
76
what prevents defecation?
external anal sphincter (normally tonically contracted)
77
individuals lacking tonic contraction of external anal sphincter?
will defecate anytime the rectum fills with fecal mater from the retrosphincteric reflex
78
how does the urge to defecate subside?
if defecation does no occur, internal anal sphincter contracts and rectum relaxes to accommodate fecal material within in
79
feces (contents)
inorganic material, undigested plant fibers, bacteria, and water
80
what kind of affect do variations in diet have on composition of feces
relatively little
81
large fraction of fecal mass is from where in origin
no dietary
82
in a starving individual defecation does or does not occur
does
83
Hirschsprung's Disease (congenital megacolon)
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
surgical removal of aganglionic segment is treatment for what?
Hirschsprung's Disease (congenital megacolon)
85
constipation (what is it)
increased time of passage or transit of material through colon
86
constipation involves what two changes?
increased storage capacity of cecum and ascending and transverse parts of colon decreased propulsive capacity of descending and sigmoid colon
87
what diminishes frequency of bowel movements?
``` 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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