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Physiology III > Mucosal Absorption I > Flashcards

Mucosal Absorption I Flashcards

1
Q

define absorption

A

process of translocating basic molecules from intestinal lumen through epithelium into vascular system

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2
Q

the end products of CHO and protein digestion are ___

A

hydrophilic

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3
Q

what’s the most important active transporter in GI?

A

Na/K ATPase

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4
Q

secondary active transport requires use of the ___ gradient

A

Na+

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5
Q

what types of transport is secondary active?

A

co-transport - aka ligands are on the same site
anti-porter/exchanger - ligands are on opposite sites

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6
Q

in secondary active co-transport, what happens once Na is bound to the transporter?

A

conformation change “delivers” ions and molecule into cell

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7
Q

which type of secondary active transport is SLUT GLUT?

A

co-transport

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8
Q

which type of secondary active transport is Na/H?

A

anti-porter/exchanger

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9
Q

Na/H transport creates the ___ gradient

A

H+

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10
Q

Na/K pump maintains ___ gradient

A

Na+

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11
Q

intracellular H+ is transported out by ___ antiport driven by which gradient?

A

Na/H
Na+ gradient

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12
Q

what is the teritiary active transport?

A

Cl/bicarb exchange

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13
Q

what does CA do?

A

catalyzes H+ and bicarb production
(tertiary active)

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14
Q

what are the three types of passive diffusion?

A

transcellular absorb
paracellular absorb
facilitated diffusion

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15
Q

what is transcellular absorption?

A

ions follow electrochemical gradient through ion channels in apical membrane

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16
Q

what is paracellular absorption?

A

ions follow electrochemical gradient and osmotic P through tight junctions

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17
Q

what is facilitated diffusion?

A

spontaneous passive diffusion of molecules/ions across membrane via specific transmembrane proteins

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18
Q

where are glc co-transporters located?

A

next to glycocalyx enzymes on apical membrane

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19
Q

how is fructose internalized?

A

facilitated diffusion
based on gradient

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20
Q

glc movement through basolateral space is driven by…

A

diffusion

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21
Q

water follows ___

A

SOLUTES

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22
Q

the concept of water following solutes is referred to as…

A

iso-osmolar absorption

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23
Q

what is used for oral rehydration therapy if the SI is still in tact?

A

SLUT GLUT - administer fluids with glc/electrolytes so slut glut gets put to use

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24
Q

SLUT GLUT stimulates water absorption by ___

A

solvent drag

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25
Q

what mechanism stays in tact in patients with D disorders?

A

SLUT GLUT solvent drag

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26
Q

CHO digestion/absorption pathophysiology is mostly due to ___ deficiency that ___ breakdown

A

enzyme
prevents breakdowns

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27
Q

what happens if you have unabsorbed CHO?

A

hold water osmolarity and cause osmotic D

28
Q

what occurs at apical membrane regarding protein digestion? (what transporters)

A

aa co-transport (Na)
four co-transport - neutral aa, dibasic aa, dicarboxylic aa, imino/proline aa
peptide carrier (H transport)
peptides further digested by intracellular enzymes

29
Q

what occurs at basolateral membrane regarding protein digestion?

A

release to extracellular space as free aa
facilitated diffusion

30
Q

how does protein absorption occur during first 24hrs of life?

A

endocytosis of entire proteins and Ig’s
receptor mediated, unspecific
done via specialized enterocytes that disappear after ~24hrs

31
Q

how does aminoaciduria develop?

A

develops from congenital defect in transport of specific aa
may still be able to do absorption of di/tri-peptides

32
Q

what is cysinuria?

A

type of aminoaciduria
transporter for dibasic aa (cystine, lysine, arginine) is ABSENT from or reduced in gut/kidney
dibasic aa lost in urine/feces
can lead to cystine stones

33
Q

what facilitates lipid digestion/absorption?

A

micelles

34
Q

how does lipid absorption occur?

A

micelle comes close to enterocyte surface and contents diffuse into cell except for bile acids which remains in intestinal lumen

35
Q

the concentration gradient ___ passive diffusion of micellar products

A

favors

36
Q

how much ingested fat is removed by SI?

A

95%

37
Q

what are the intracellular events of lipid absorption? (two paths)

A

lipids reassemble in cells (form triglyceride)
MONOGLYCERIDE ACYLATION PATH
PHOSPHATIDIC ACID PATH
chylomicrons

38
Q

describe the monoglyceride acylation pathway of lipid intracellular absorption

A

2 mono + fatty acid acyl CoA = triglyceride

39
Q

describe the phosphatidic acid pathway of lipid intracellular absorption

A

glycolysis -> P-glycerol or diOH-acetone P -> alpha-glycerolP -> triglycerides

40
Q

what are chylomicrons?

A

core of triglyceride and cholesterol surrounded by phospholipase and apoproteins

aka transport vesicle for lipids in lacteals

41
Q

what are lacteals?

A

lymphatic vessels of SI villi that absorb digested fats

42
Q

water soluble chylomicrons ___ phospholipids, triglycerides, proteins

A

coat

43
Q

describe the process of chylomicron assembling?

A
  1. fa, monoglyceride converts into triglycerides in ER
  2. cholesterol is re-esterified
  3. triglycerides ad cholesterol are packaged into chylomicrons
  4. apoproteins are embedded in chylomicrons
44
Q

what are apoproteins?

A

structural components of lipoprotein particles
ligand for cell surface receptors

45
Q

without apoproteins, large quantities of triglycerides would accumulate where?

A

enterocytes

46
Q

what are the five lipoprotein vehicles?

A

chylomicrons
VLDL
IDL
LDL
HDL

47
Q

chylomicrons are taken up by…

A

lacteals

48
Q

where do lacteals drain?

A

into cisterna chyli (abdomen duct)
then thoracic duct
lastly, internal jugular vein

49
Q

bile acids remain in the ___.

A

intestinal lumen

50
Q

what happens regarding lipids if there is a lack of bile acids?

A

unable to digest fats

51
Q

where is the bile acid transporter located and what is it called?

A

in ileum
Na-bile acid-cotransport

52
Q

are bile acids recycled?

A

YES, returns to portal system

53
Q

what is enterohepatic circulation?

A

refers to the process of bile acid recycling, storage, and release into SI lumen

54
Q

bile acids are synthesized from ___ in the liver

A

cholesterol

55
Q

which vein takes bile acids back to the liver?

A

portal vein

56
Q

where do bile acids go if NOT recycled into the liver?

A

show up in blood plasma

57
Q

are liver shunts acquired or congenital?

A

can be BOTH

58
Q

how does a patient acquire a liver shunt?

A

liver disease

59
Q

which species most likely gets extra-hepatic liver shunts?

A

small and toy breeds

60
Q

which species most likely gets intra-hepatic liver shunts?

A

large breed dogs

61
Q

what are body affects of liver shunts?

A

poor growth/development
neurologic changes
behavior change
increased thirst, frequent urination
V
accumulation of toxins and metabolic waste products can lead to HEPATIC ENCEPHALOPATHY

62
Q

what is hepatic encephalopathy?

A

neurological disturbances in patients with liver dysfunction (shunt)
caused by effects on brain of substances that under normal circumstances are efficiently metabolized by liver

63
Q

what does a bile acid test do?

A

liver function test
indicates degree of inflammation/damage

64
Q

what does it mean if the bile acid test comes back normal?

A

low initial AND low 2hrs levels of bile acid

65
Q

what does it mean if the bile acid test is elevated at rest?

A

bile acids remain in circulation
(shunt, liver disease, gallbladder issue, etc)

66
Q

what does it mean if the bile acid test has normal resting level but elevated 2hrs levels?

A

bile acids are very slowly reabsorbed and escape into systemic circulation

Physiology III (18 decks)

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