Bile and Large Intestine Flashcards Preview

SF4 Exam I > Bile and Large Intestine > Flashcards

Flashcards in Bile and Large Intestine Deck (87):
1

bile is required for what?

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

2

bile is produced by what and when?

hepatocytes
produced continuously

3

bile is stored where and when

gallbladder
during interdigestive period

4

bile composition (name whats in it)

bile acids
phospholipids
cholesterol
bile pigments
electrolytes

5

primary bile acids are synthesized where and from what

liver
from cholesterol

6

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

secondary bile acids
bacteria in intestine

7

in the liver what happens to bile acids

the are conjugated to glycine or taurine

8

bile acids are conjugated to what?

glycine or taurine

9

bile salt (what is it)

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

10

bile acids are conjugated why?

more water soluble at intestinal pH

11

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

ionized and thus cannot be passively absorbed

12

in aqueous solutions what do bile salts do to lipids?

orient around droplets of lipid and keep lipid dispersed in emulsion

13

bile salts are polar, non polar, or amphipathic?

amphipathic

14

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

oriented towards aqueous solution of intestinal lumen

15

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

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

16

primary bile salts include (name a few)

cholates
chenodeoxycholates

17

secondary bile salts include

deoxycholates
ursodeoxycholates
lithocholates

18

what type of phospholipid primarily makes up bile is?

lecithins

19

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

bile salt micelles

20

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

phospholipids

21

before cholesterol can be secreted in bile what must occur?

solubilized by bile salt micelles

22

what is the primary excretory pathway for cholesterol and how?

bile
via loss of bile salts in feces

23

what happens if more cholesterol is present than can be solubilized

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

24

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

bilirubin (metabolite of hemoglobin)

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